U.S. patent application number 10/439440 was filed with the patent office on 2003-10-16 for specifying and targeting portions of a graphical program for real-time execution on an embedded processor.
This patent application is currently assigned to National Instruments Corporation. Invention is credited to DeKey, Samson, Kodosky, Jeffrey L., Rogers, Steve, Shah, Darshan.
Application Number | 20030196187 10/439440 |
Document ID | / |
Family ID | 25431933 |
Filed Date | 2003-10-16 |
United States Patent
Application |
20030196187 |
Kind Code |
A1 |
Kodosky, Jeffrey L. ; et
al. |
October 16, 2003 |
Specifying and targeting portions of a graphical program for
real-time execution on an embedded processor
Abstract
A computer-based virtual instrumentation system including a host
computer and an embedded system or device, wherein graphical
programs created using the computer system can be downloaded to the
embedded system for execution in a real-time or more deterministic
manner. The present invention thus provides a method for
automatically generating an embedded application in response to a
graphical program created by a user. This provides the user the
ability to develop or define instrument functionality using
graphical programming techniques, while enabling the resulting
program to operate in an embedded real-time system. The invention
includes a novel method for configuring the embedded system. During
execution of a graphical program in the embedded system, the block
diagram portion executes in the embedded system, and the host CPU
executes front panel display code to display on the screen the
graphical front panel of the graphical program. The embedded system
and the host computer exchange data using a front panel protocol to
enable this operation. The present invention also includes improved
debugging support for graphical programs executing on the embedded
system. The host graphical programming system thus provides the
user interface for graphical programs executing on the embedded
system, essentially acting as the front panel "browser" for
embedded applications. The host LabVIEW can also act as an
independent application communicating with embedded LabVIEW through
the shared memory. The host graphical programming system further
provides a seamless environment in which the user can develop an
embedded application using high level graphical programming
techniques.
Inventors: |
Kodosky, Jeffrey L.;
(US) ; Shah, Darshan; (US) ; DeKey,
Samson; (US) ; Rogers, Steve; (US) |
Correspondence
Address: |
Jeffrey C. Hood
Meyertons, Hood, Kivlin, Kowert & Goetzel PC
P.O. Box 398
Austin
TX
78767
US
|
Assignee: |
National Instruments
Corporation
|
Family ID: |
25431933 |
Appl. No.: |
10/439440 |
Filed: |
May 16, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10439440 |
May 16, 2003 |
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09631528 |
Aug 3, 2000 |
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09631528 |
Aug 3, 2000 |
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08912445 |
Aug 18, 1997 |
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6173438 |
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Current U.S.
Class: |
717/109 ;
717/105; 717/107; 717/113; 719/327 |
Current CPC
Class: |
G06F 9/44505 20130101;
G06F 8/34 20130101 |
Class at
Publication: |
717/109 ;
717/113; 717/105; 717/107; 709/327 |
International
Class: |
G06F 009/44; G06F
009/00 |
Claims
1. A memory medium which stores program instructions for
configuring a device, wherein the device includes an embedded
processor and an embedded memory, wherein the program instructions
are executable to perform: storing a graphical program in a memory,
wherein a first portion of the graphical program requires a greater
real-time response, and wherein a second portion of the graphical
program requires a lesser real-time response; generating code that
is executable on the device for real-time execution based on the
first portion of the graphical program which requires a greater
real-time response.
2. The memory medium of claim 1, wherein the program instructions
are further executable to perform: receiving user input selecting
said first portion of the graphical program requiring a greater
real-time response.
3. The memory medium of claim 1, wherein said receiving user input
selecting said first portion of the graphical program requiring a
greater real-time response comprises: receiving user input
indicating an execution engine comprised in the device for
executing the first portion of the graphical program requiring a
greater real-time response; wherein said generating code that is
executable on the device for real-time execution based on the first
portion of the graphical program which requires real-time execution
is performed in response to said receiving user input indicating an
execution engine.
4. The memory medium of claim 1, wherein the graphical program
comprises a model.
5. The memory medium of claim 1, wherein the graphical program
comprises a plurality of interconnected nodes that visually
represent functionality of a procedure.
6. The memory medium of claim 5, wherein the first portion of the
graphical program comprises at least a portion of the plurality of
interconnected nodes.
7. The memory medium of claim 5, wherein the first portion of the
graphical program comprises only a portion of the plurality of
interconnected nodes.
8. The memory medium of claim 1, wherein the graphical program
comprises a front panel portion, wherein the front panel portion
implements a Graphical User Interface for the graphical
program.
9. The memory medium of claim 8, wherein the second portion of the
graphical program comprises the front panel portion.
10. The memory medium of claim 1, wherein generating further
comprises establishing an inter-process communication link between
the first portion of the graphical program which requires greater
real-time response and the second portion of the graphical program
which requires lesser real-time response.
11. The memory medium of claim 10, wherein the second portion of
the graphical program which requires lesser real-time response is
operable to receive output from the first portion of the graphical
program which requires greater real-time response via the
inter-process communications link.
12. The memory medium of claim 11, wherein the second portion of
the graphical program which requires lesser real-time response is
operable to perform: processing the output from the first portion
of the graphical program.
13. The memory medium of claim 12, wherein processing the output
from the first portion of the graphical program comprises:
displaying the output on a computer display.
14. The memory medium of claim 1, wherein the program instructions
are further executable to perform: deploying the generated code
onto the device for execution.
15. The memory medium of claim 14, wherein the program instructions
are further executable to perform: executing the first portion of
the graphical program on the device, wherein said executing
comprises the embedded processor executing the first portion of the
graphical program from the embedded memory.
16. The memory medium of claim 14, wherein the program instructions
are further executable to perform: executing the second portion of
the graphical program requiring a lesser real-time response on a
host computer.
17. The memory medium of claim 1, wherein the program instructions
further comprise a set of pre-defined instructions for generating
machine language code corresponding to the first portion of the
graphical program requiring a greater real-time response.
18. A method comprising: storing a graphical program in a memory,
wherein a first portion of the graphical program requires a greater
real-time response, and wherein a second portion of the graphical
program requires a lesser real-time response; and generating code
that is executable on an embedded device for real-time execution
based on the first portion of the graphical program which requires
a greater real-time response, wherein the embedded device includes
an embedded processor and an embedded memory.
19. The method of claim 18, wherein the graphical program comprises
a model.
20. The method of claim 18, wherein the graphical program comprises
a plurality of interconnected nodes that visually represent
functionality of a procedure.
21. The method of claim 18, wherein said requiring a greater
real-time response or a lesser real-time response comprises:
requiring a real-time execution or not requiring real-time
execution.
22. The method of claim 18, wherein the graphical program comprises
a data flow diagram.
23. A method comprising: receiving user input specifying a
graphical program model, the graphical program model including
sections, a first subset of the sections designated post-processing
unit sections requiring a lesser real-time response, and a second
subset of the section designated first processing unit sections
requiring a greater real-time response; generating software source
code for the graphical program model using the second subset,
wherein the software course code is deployable onto an embedded
device for execution; and linking the software source code to the
first subset via an inter-process communication link; and compiling
the software source code into executable code.
24. The method of claim 23, further comprising: deploying the
executable code onto an embedded memory on the embedded device; and
an embedded processor comprised in the embedded device executing
the executable code.
25. The method of claim 24, further comprising: executing the first
subset of the sections designated post-processing unit sections
requiring a lesser real-time response on a host computer.
26. The method of claim 25, wherein said executing the executable
code generates data, the method further comprising: the
post-processing unit sections executing to receive the data from
said executing; and post-processing the received data.
27. The method of claim 26, wherein said post-processing the
received data comprises displaying the received data on a computer
display.
28. The method of claim 26, wherein said embedded processor
executing the executable code is performed substantially
concurrently with said executing the first subset of the
sections.
29. The method of claim 23, wherein said receiving user input
comprises receiving user input through a graphical user interface
(GUI).
30. The method of claim 23, wherein the graphical program comprises
a plurality of interconnected nodes that visually represent
functionality of a procedure.
31. A method comprising: identifying portions of a model as
requiring a greater real-time response or a lesser real-time
response; and generating code that is capable of greater real-time
response based on the portions of a model requiring a greater
real-time response, wherein the generated code is targeted for
execution on an embedded device comprising an embedded processor
and an embedded memory.
32. A system for configuring a device, wherein the device includes
an embedded processor and an embedded memory, comprising: a host
computer system, comprising: a CPU; and a first memory coupled to
the CPU; and a device, coupled to the host computer system,
comprising: an embedded processor; and an embedded memory coupled
to the embedded processor; wherein the first memory stores program
instructions which are executable by the CPU to: store portions of
a graphical program, wherein the graphical program comprises a
plurality of interconnected nodes that visually represent
functionality of a procedure, wherein a first portion requires a
greater real-time response, and wherein a second portion requires a
lesser real-time response; and generate code that is executable on
the device for real-time execution based on the first portion of
the graphical program which requires greater real-time
response.
33. A system for configuring a device, wherein the device includes
an embedded processor and an embedded memory, comprising: means for
storing a graphical program in a memory, wherein a first portion of
the graphical program requires a greater real-time response, and
wherein a second portion of the graphical program requires a lesser
real-time response; means for generating code that is executable on
the device for real-time execution based on the first portion of
the graphical program which requires a greater real-time
response.
34. A memory medium which stores program instructions for
configuring a device, wherein the device includes an embedded
processor and an embedded memory, wherein the program instructions
are executable to perform: storing portions of a block diagram,
wherein a first portion requires a greater real-time response, and
wherein a second portion requires a lesser real-time response; and
generating code that is executable on the device for real-time
execution based on the first portion of the block diagram which
requires greater real-time response.
Description
CONTINUATION DATA
[0001] This application is a continuation of U.S. patent
application Ser. No. 09/631,528 filed on Aug. 3, 2000 titled
"System and Method for Initializing a Device for Execution of
Graphical Programs", whose inventors are Jeffrey L. Kodosky,
Darshan Shah, Samson DeKey, and Steven W. Rogers, which is a
continuation of U.S. patent application Ser. No. 08/912,445 filed
on Aug. 18, 1997 titled "Embedded Graphical Programming System",
whose inventors are Jeffrey L. Kodosky, Darshan Shah, Samson DeKey,
and Steven W. Rogers, which issued as U.S. Pat. No. 6,173,438 on
Jan. 9, 2001, which is a Continued Prosecution Application of U.S.
patent application Ser. No. 08/912,445 filed on Aug. 18, 1997
titled "Embedded Graphical Programming System", whose inventors are
Jeffrey L. Kodosky, Darshan Shah, Samson DeKey, and Steven W.
Rogers.
RESERVATION OF COPYRIGHT
[0002] A portion of the disclosure of this patent document contains
material to which a claim of copyright protection is made. The
copyright owner has no objection to the facsimile reproduction by
anyone of the patent document or the patent disclosure as it
appears in the Patent and Trademark Office patent file or records,
but reserves all other rights whatsoever.
FIELD OF THE INVENTION
[0003] The present invention relates to graphical programming, and
in particular to a system and method for executing a portion or all
of a graphical program in an embedded system, wherein a user
interface portion of the graphical programming system optionally
also executes on the host CPU.
DESCRIPTION OF THE RELATED ART
[0004] Traditionally, high level text-based programming languages
have been used by programmers in writing applications programs.
Many different high level programming languages exist, including
BASIC, C, FORTRAN, Pascal, COBOL, ADA, APL, etc. Programs written
in these high level languages are translated to the machine
language level by translators known as compilers. The high level
programming languages in this level, as well as the assembly
language level, are referred to as text-based programming
environments.
[0005] Increasingly computers are required to be used and
programmed by those who are not highly trained in computer
programming techniques. When traditional text-based programming
environments are used, the user's programming skills and ability to
interact with the computer system often become a limiting factor in
the achievement of optimal utilization of the computer system.
[0006] There are numerous subtle complexities which a user must
master before he can efficiently program a computer system in a
text-based environment. The task of programming a computer system
to model a process often is further complicated by the fact that a
sequence of mathematical formulas, mathematical steps or other
procedures customarily used to conceptually model a process often
does not closely correspond to the traditional text-based
programming techniques used to program a computer system to model
such a process. In other words, the requirement that a user program
in a text-based programming environment places a level of
abstraction between the user's conceptualization of the solution
and the implementation of a method that accomplishes this solution
in a computer program. Thus, a user often must substantially master
different skills in order to both conceptually model a system and
then to program a computer to model that system. Since a user often
is not fully proficient in techniques for programming a computer
system in a text-based environment to implement his model, the
efficiency with which the computer system can be utilized to
perform such modeling often is reduced.
[0007] Examples of fields in which computer systems are employed to
model and/or control physical systems are the fields of
instrumentation, process control, and industrial automation.
Computer modeling or control of devices such as instruments or
industrial automation hardware has become increasingly desirable in
view of the increasing complexity and variety of instruments and
devices available for use. However, due to the wide variety of
possible testing/control situations and environments, and also the
wide array of instruments or devices available, it is often
necessary for a user to develop a program to control a desired
system. As discussed above, computer programs used to control such
systems had to be written in conventional text-based programming
languages such as, for example, assembly language, C, FORTRAN,
BASIC, or Pascal. Traditional users of these systems, however,
often were not highly trained in programming techniques and, in
addition, traditional text-based programming languages were not
sufficiently intuitive to allow users to use these languages
without training. Therefore, implementation of such systems
frequently required the involvement of a programmer to write
software for control and analysis of instrumentation or industrial
automation data. Thus, development and maintenance of the software
elements in these systems often proved to be difficult.
[0008] U.S. Pat. No. 4,901,221 to Kodosky et al discloses a
graphical system and method for modeling a process, i.e. a
graphical programming environment which enables a user to easily
and intuitively model a process. The graphical programming
environment disclosed in Kodosky et al can be considered the
highest and most intuitive way in which to interact with a
computer. A graphically based programming environment can be
represented at level above text-based high level programming
languages such as C, Pascal, etc. The method disclosed in Kodosky
et al allows a user to construct a diagram using a block diagram
editor, such that the diagram created graphically displays a
procedure or method for accomplishing a certain result, such as
manipulating one or more input variables to produce one or more
output variables. In response to the user constructing a data flow
diagram or graphical program using the block diagram editor,
machine language instructions are automatically constructed which
characterize an execution procedure which corresponds to the
displayed procedure. Therefore, a user can create a computer
program solely by using a graphically based programming
environment. This graphically based programming environment may be
used for creating virtual instrumentation systems, industrial
automation systems and modeling processes, as well as for any type
of general programming.
[0009] Therefore, Kodosky et al teaches a graphical programming
environment wherein a user places or manipulates icons in a block
diagram using a block diagram editor to create a data flow
"program." A graphical program for controlling or modeling devices,
such as instruments, processes or industrial automation hardware,
is referred to as a virtual instrument (VI). In creating a virtual
instrument, a user preferably creates a front panel or user
interface panel. The front panel includes various front panel
objects, such as controls or indicators that represent the
respective input and output that will be used by the graphical
program or VI, and may include other icons which represent devices
being controlled. When the controls and indicators are created in
the front panel, corresponding icons or terminals are automatically
created in the block diagram by the block diagram editor.
Alternatively, the user can first place terminal icons in the block
diagram which cause the display of corresponding front panel
objects in the front panel. The user then chooses various functions
that accomplish his desired result, connecting the corresponding
function icons between the terminals of the respective controls and
indicators. In other words, the user creates a data flow program,
referred to as a block diagram, representing the graphical data
flow which accomplishes his desired function. This is done by
wiring up the various function icons between the control icons and
indicator icons. The manipulation and organization of icons in turn
produces machine language that accomplishes the desired method or
process as shown in the block diagram.
[0010] A user inputs data to a virtual instrument using front panel
controls. This input data propagates through the data flow block
diagram or graphical program and appears as changes on the output
indicators. In an instrumentation application, the front panel can
be analogized to the front panel of an instrument. In an industrial
automation application the front panel can be analogized to the MMI
(Man Machine Interface) of a device. The user adjusts the controls
on the front panel to affect the input and views the output on the
respective indicators.
[0011] Thus, graphical programming has become a powerful tool
available to programmers. Graphical programming environments such
as the National Instruments LabVIEW product have become very
popular. Tools such as LabVIEW have greatly increased the
productivity of programmers, and increasing numbers of programmers
are using graphical programming environments to develop their
software applications. In particular, graphical programming tools
are being used for test and measurement, data acquisition, process
control, man machine interface (MMI), and supervisory control and
data acquisition (SCADA) applications, among others.
[0012] In many instrumentation or industrial automation
applications, it is necessary to guarantee real-time performance
and/or more deterministic behavior for proper operation. However,
current computer operating systems generally cannot guarantee
real-time or deterministic performance. This is primarily due to
various overhead issues, such as context switches, driver calls,
disk caching, user I/O and interrupts, which limit the operating
system's ability to guarantee real-time performance. Therefore, it
would be desirable to provide a programmable environment which can
guarantee real-time performance. It is further desirable to provide
the user the maximum amount of flexibility to create his/her own
real-time applications and/or define his/her own instrument
real-time functionality using a high level graphical programming
environment.
[0013] In many instrumentation or industrial automation
applications, it is necessary to guarantee real-time performance
and/or more deterministic behavior for proper operation. However,
most desktop computer operating systems (e.g. Windows 95) generally
cannot guarantee real-time or deterministic performance. This is
primarily due to the fact that desktop operating systems
(specifically, its scheduler) are designed for high throughput at
the expense of determinism. This is also due to various overhead
issues, such as context switches, driver calls, disk caching, user
I/O and interrupts, which limit the operating system's ability to
guarantee real-time performance. Therefore, it would be desirable
to provide a programmable environment which can guarantee real-time
performance. It is further desirable to provide the user the
maximum amount of flexibility to create his/her own real-time
applications and/or define his/her own instrument real-time
functionality using a high level graphical programming
environment.
SUMMARY OF THE INVENTION
[0014] The present invention comprises a computer-based virtual
instrumentation system, wherein graphical programs created using
the computer system can be downloaded to an embedded system for
execution in a real-time or deterministic manner. The present
invention thus provides a method for automatically generating an
embedded application in response to a graphical program created by
a user. This provides the user the ability to develop or define
instrument functionality using graphical programming techniques,
while enabling the resulting program to operate in an embedded
real-time system.
[0015] The preferred embodiment of the invention comprises a
general purpose host computer system which includes a CPU and
memory, and an embedded system or device coupled to the host
computer system which also includes a CPU and memory, referred to
as an embedded CPU and embedded memory. The embedded memory stores
a real-time operating system kernel which provides basic OS
services. The embedded system also includes a graphical program
execution engine, referred to as embedded LabVIEW, which enables
the embedded system to execute the graphical program.
[0016] In one embodiment, the embedded system is an interface card
or device such as an Intelligent DAQ card or VXI controller
interface card coupled to (or plugged in to) the host computer. In
this embodiment, the embedded memory further includes a shared
memory portion used for bi-directional communication between the
host computer and the embedded system. In an alternate embodiment,
the embedded system comprises an instrument or device connected to
the computer, such as through a network connection. It is noted
that the instrument or device comprising the embedded system can
take any of various forms, as desired.
[0017] The host computer system includes a host graphical
programming system, e.g., host LabVIEW, which is used to develop a
graphical program. The host LabVIEW also executes code to display
the front panel of a graphical program whose block diagram is
executing on the embedded system. The host computer system also
includes software according to the present invention which is
operable to download software into the embedded system to configure
or initialize the embedded system.
[0018] In one embodiment the embedded system has non-volatile
storage media, and at power up the embedded system initializes and
configures itself with a real time kernel and an embedded graphical
programming system. In alternative embodiment where the embedded
system does not have non-volatile boot media for storing an
operating system and the embedded graphical programming system, the
embedded system receives OS and programs from the host computer. In
this case, the embedded system receives its OS and programs from
the host computer. Since the operating system and application
programs typically reside in a non-volatile media, such as a hard
drive, and a computer system typically `boots` the operating system
from the hard drive, its absence means that an alternative method
of booting needs to present.
[0019] When the embedded system boots up, the embedded system
executes the BIOS code in the read-only memory (ROM), as is typical
in any computer system. The BIOS code then executes a BIOS
extension program present in memory which requests the operating
system kernel from the host computer system. Therefore, the host
computer first loads a kernel or basic operating system onto the
embedded system. The host computer also transfers one or more other
loader applications. As a result, an embedded graphical programming
system and various configuration information are then loaded onto
the embedded system. In the preferred embodiment, the embedded
graphical programming system is embedded LabVIEW. Various software
drivers are then loaded onto the embedded system. These components
are loaded onto the embedded system using the shared memory and
using a shared memory protocol. Thus, once the embedded system is
initialized, the embedded system includes a kernel, an embedded
graphical programming execution system, e.g., embedded LabVIEW, and
any necessary device drivers.
[0020] After the system has been configured, the user first creates
a graphical program on the host computer system using the host
LabVIEW, which includes arranging on the screen a plurality of
nodes comprising the graphical program. The host computer then
compiles the graphical program to produce a compiled graphical
program, depending on the selected target. The user also preferably
selects the execution engine for the graphical program, i.e.
whether the program will run on the host computer or on the
embedded system. If the user has selected the execution engine in
the embedded system, the host computer downloads the relevant part
of the compiled graphical program to the device through a front
panel protocol. The device then executes the compiled graphical
program. This includes executing the execution engine to execute
the compiled graphical program, as well as executing the OS kernel
for basic OS services. Due to the use of a real-time operating
system and reduced OS overhead, the embedded system or device
executes the compiled graphical program in a deterministic
manner.
[0021] The graphical program includes a graphical diagram and a
graphical front panel. The graphical front panel is usable for
providing/displaying input/output to/from the compiled graphical
program executing on the device. During execution of a graphical
program in the embedded system, the block diagram portion executes
in the embedded system, and the host CPU executes front panel
display code to display on the screen the graphical front panel of
the graphical program. The embedded system and the host computer
exchange data using a front panel protocol to enable this
operation. Thus, when the device executing the compiled graphical
program generates output data for display in the front panel of the
graphical program, the output data is transferred to the host
computer system, and the host computer system displays the output
data in the graphical front panel of the graphical program. In a
similar manner, when the user provides input to the graphical
program via the graphical front panel, the host computer system
displays the input data in the graphical front panel of the
graphical program and transfers the input data to the embedded
system so that the device can utilize the user input during
execution of the compiled graphical program.
[0022] The present invention also includes improved debugging
support for graphical programs executing on the embedded system.
According to the present invention, the user can debug a graphical
program executing on embedded LabVIEW utilizing the block diagram
of the graphical program displayed on the display screen by the
host LabVIEW. The host LabVIEW and embedded LabVIEW exchange
information to enable the user to view debugging information, such
as execution highlighting and probe information, on the display
screen for a graphical program executing on the embedded system.
This provides greatly simplified debugging for embedded graphical
programs.
[0023] The host graphical programming system or host LabVIEW thus
provides the user interface for graphical programs executing on the
embedded system. The host LabVIEW thus essentially acts as the
front panel "browser" for embedded LabVIEW applications. The host
LabVIEW can also act as an independent application communicating
with embedded LabVIEW through the shared memory and/or network. The
host graphical programming system further provides a seamless
environment in which the user can develop an embedded application
using high level graphical programming techniques.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] A better understanding of the present invention can be
obtained when the following detailed description of the preferred
embodiment is considered in conjunction with the following
drawings, in which:
[0025] FIG. 1 illustrates an instrumentation control system;
[0026] FIG. 1A illustrates an industrial automation system;
[0027] FIG. 2 is a block diagram illustrating the computer system
of FIGS. 1 or 1A;
[0028] FIG. 3 is a block diagram illustrating an interface card
configured with an embedded CPU and memory according to the present
invention;
[0029] FIG. 3A is an alternate embodiment of a block diagram
illustrating an interface card configured with an embedded CPU and
memory according to the present invention, and also including a
programmable memory;
[0030] FIG. 4 is a high level flowchart diagram illustrating
initialization of the embedded system according to the present
invention;
[0031] FIGS. 5A and 5B are a more detailed flowchart diagram
illustrating initialization of the embedded system;
[0032] FIG. 6 is a flowchart diagram illustrating creation of an
embedded graphical program according to the preferred embodiment of
the invention;
[0033] FIG. 7 is a flowchart diagram illustrating beginning
execution of the embedded graphical program;
[0034] FIG. 8 is a flowchart diagram illustrating execution of the
embedded graphical program;
[0035] FIG. 9 illustrates the elements of a graphical program;
[0036] FIG. 10 conceptually illustrates a graphical program
executing on the embedded system, and the host LabVIEW implementing
the user interface or front panel for the graphical program;
[0037] FIG. 11 conceptually illustrates the front panel displayed
on the host computer 102 being used for debugging a graphical
program executing on the embedded system;
[0038] FIG. 12 illustrates the shared memory structure of the
shared memory protocol used for communication between the host
LabVIEW and embedded LabVIEW;
[0039] FIG. 13 illustrates the structure of a data channel in the
shared memory protocol;
[0040] FIG. 14 illustrates the structure of a shared memory block
in the shared memory protocol;
[0041] FIG. 15 illustrates the data channel structure in the shared
memory protocol; and
[0042] FIG. 16 is a table illustrating the privileges of token
owners and non-owners.
[0043] While the invention is susceptible to various modifications
and alternative forms specific embodiments are shown by way of
example in the drawings and will herein be described in detail. It
should be understood however, that drawings and detailed
description thereto are not intended to limit the invention to the
particular form disclosed. But on the contrary the invention is to
cover all modifications, equivalents and alternative following
within the spirit and scope of the present invention as defined by
the appended claims.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0044] Incorporation by Reference
[0045] The following U.S. Patents and patent applications are
hereby incorporated by reference in their entirety as though fully
and completely set forth herein.
[0046] U.S. Pat. No. 4,901,221 titled "Graphical System for
Modeling a Process and Associated Method," issued on Feb. 13,
1990.
[0047] U.S. Pat. No. 4,914,568 titled "Graphical System for
Modeling a Process and Associated Method," issued on Apr. 3,
1990.
[0048] U.S. Pat. No. 5,481,741 titled "Method and Apparatus for
Providing Attribute Nodes in a Graphical Data Flow
Environment".
[0049] U.S. patent application Ser. No. 08/292,091 filed Aug. 17,
1994, titled "Method and Apparatus for Providing Improved Type
Compatibility and Data Structure Organization in a Graphical Data
Flow Diagram".
[0050] U.S. Pat. No. 5,475,851 titled "Method and Apparatus for
Improved Local and Global Variable Capabilities in a Graphical Data
Flow Program".
[0051] U.S. Pat. No. 5,497,500 titled "Method and Apparatus for
More Efficient Function Synchronization in a Data Flow
Program".
[0052] U.S. patent application Ser. No. 08/474,307 titled "Method
and Apparatus for Providing Stricter Data Type Capabilities in a
Graphical Data Flow Environment" filed Jun. 7, 1995.
[0053] U.S. Pat. No. 5,481,740 titled "Method and Apparatus for
Providing Autoprobe Features in a Graphical Data Flow Diagram".
[0054] U.S. Pat. No. 5,504,917 titled "Method and Apparatus for
Providing Picture Generation and Control Features in a Graphical
Data Flow Environment"
[0055] U.S. patent application Ser. No. 08/870,262 titled "System
and Method for Detecting Differences in Graphical Programs" filed
Jun. 6, 1997, whose inventor is Ray Hsu.
[0056] U.S. patent application Ser. No. 08/912,427 filed on Mar.
22, 2000 titled "System and Method for Converting Graphical
Programs Into Hardware Implementations", whose inventors are
Jeffrey L. Kodosky, Hugo Andrade, Brian Keith Odom and Cary Paul
Butler, which issued as U.S. Pat. No. 6,219,628 on Apr. 17,
2001.
[0057] U.S. patent application Ser. No. 08/912,445 filed on Aug.
18, 1997 titled "Embedded Graphical Programming System", whose
inventors are Jeffrey L. Kodosky, Darshan Shah, Samson DeKey, and
Steven W. Rogers, which issued as U.S. Pat. No. 6,173,438 on Jan.
9, 2001.
[0058] The above-referenced patents and patent applications
disclose various aspects of the LabVIEW graphical programming and
development system.
[0059] The LabVIEW and BridgeVIEW graphical programming manuals,
including the "G Programming Reference Manual", available from
National Instruments Corporation, are also hereby incorporated by
reference in their entirety.
[0060] FIGS. 1 and 1A--Instrumentation and Industrial Automation
Systems
[0061] Referring now to FIG. 1, an instrumentation control system
100 is shown. The system 100 comprises a host computer 102 which
connects to one or more instruments. The host computer 102
comprises a CPU, a display screen, memory, and one or more input
devices such as a mouse or keyboard as shown. The computer 102
connects through the one or more instruments to analyze, measure or
control a unit under test (UUT) or process 130.
[0062] The one or more instruments may include a GPIB instrument
112, a data acquisition board 114, and/or a VXI instrument 116. The
GPIB instrument 112 is coupled to the computer 102 via a GPIB
interface card 122 provided by the computer 102. The data
acquisition board 114 is coupled to the computer 102, and
preferably interfaces through signal conditioning circuitry 124 to
the UUT. The signal conditioning circuitry 124 preferably comprises
an SCXI (Signal Conditioning eXtensions for Instrumentation)
chassis comprising one or more SCXI modules 126. Both the GPIB card
122 and the DAQ card 114 are typically plugged in to an I/O slot in
the computer 102, such as a PCI bus slot, a PC Card slot, or an
ISA, EISA or MicroChannel bus slot provided by the computer 102.
However, these cards 122 and 114 are shown external to computer 102
for illustrative purposes. The VXI instrument 116 is coupled to the
computer 102 via a VXI bus, MXI bus, or other serial or parallel
bus provided by the computer 102. The computer 102 preferably
includes VXI interface logic, such as a VXI, MXI or GPIB interface
card (not shown) comprised in the computer. A serial instrument
(not shown) may also be coupled to the computer 102 through a
serial port, such as an RS-232 port, USB (Universal Serial bus) or
IEEE 1394 or 1394.2 bus, provided by the computer 102. In typical
instrumentation control systems an instrument will not be present
of each interface type, and in fact many systems may only have one
or more instruments of a single interface type, such as only GPIB
instruments.
[0063] In the embodiment of FIG. 1, one or more of the devices
connected to the computer 102 comprises an embedded system which
includes an embedded CPU and memory according to the present
invention. The embedded system executes a real time kernel and a
graphical program execution engine to enable execution of graphical
programs in a real-time or deterministic manner. For example, one
or more of the GPIB card 122, the DAQ card 114, or the VXI card
comprise an embedded system according to the present invention.
Alternatively, or in addition, one or more of the GPIB instrument
112, the VXI instrument 116, or the serial instrument comprise an
embedded system according to the present invention. In one, the
embedded system further comprises programmable hardware, such as an
FPGA (field programmable gate array).
[0064] The instruments are coupled to the unit under test (UUT) or
process 130, or are coupled to receive field signals, typically
generated by transducers. The system 100 may be used in a data
acquisition and control application, in a test and measurement
application, a process control application, or a man-machine
interface application.
[0065] Referring now to FIG. 1A, an industrial automation system
140 is shown. The industrial automation system 140 is similar to
the instrumentation or test and measurement system 100 shown in
FIG. 1. Elements which are similar or identical to elements in FIG.
1 have the same reference numerals for convenience. The system 140
comprises a computer 102 which connects to one or more devices or
instruments. The computer 102 comprises a CPU, a display screen,
memory, and one or more input devices such as a mouse or keyboard
as shown. The computer 102 connects through the one or more devices
to a process or device 160 to perform an automation function, such
as MMI (Man Machine Interface), SCADA (Supervisory Control and Data
Acquisition), portable or distributed acquisition, advanced
analysis, or control.
[0066] The one or more devices may include a data acquisition board
114, a serial instrument 142, a PLC (Programmable Logic Controller)
144, or a fieldbus network card 156. The data acquisition board 114
is coupled to or comprised in the computer 102, and preferably
interfaces through signal conditioning circuitry 124 to the process
160. The signal conditioning circuitry 124 preferably comprises an
SCXI (Signal Conditioning extensions for Instrumentation) chassis
comprising one or more SCXI modules 126. The serial instrument 142
is coupled to the computer 102 through a serial interface card 152,
or through a serial port, such as an RS-232 port, provided by the
computer 102. The PLC 144 couples to the computer 102 through a
serial port, Ethernet port, or a proprietary interface. The
fieldbus interface card 156 is preferably comprised in the computer
102 and interfaces through a fieldbus network to one or more
fieldbus devices, such as valve 146. Each of the DAQ card 114, the
serial card 152 and the fieldbus card 156 are typically plugged in
to an I/O slot in the computer 102 as described above. However,
these cards 114, 12 and 156 are shown external to computer 102 for
illustrative purposes. In typical industrial automation systems a
device will not be present of each interface type, and in fact many
systems may only have one or more devices of a single interface
type, such as only PLCs. The devices are coupled to the device or
process 160.
[0067] In the embodiment of FIG. 1A, one or more of the devices
connected to the computer 102 comprise an embedded system according
to the present invention which includes an embedded CPU and memory
according to the present invention. As noted above, the embedded
system executes a real time kernel and a graphical program
execution engine to enable execution of graphical programs in a
real-time or deterministic manner. For example, one or more of the
data acquisition board 114, the serial instrument 142, the serial
interface card 152, the PLC 144, or the fieldbus network card 156
comprise an embedded system according to the present invention. In
one embodiment, the embedded system further includes programmable
hardware, such as an FPGA (field programmable gate array).
[0068] Referring again to FIGS. 1 and 1A, the host computer 102
preferably includes a host memory media, such as a magnetic media,
CD-ROM, or floppy disks 104. The memory media preferably stores a
host graphical programming development system for developing and
executing graphical programs. The memory media also stores computer
programs according to the present invention which are executable to
download a graphical program for execution on an embedded system
coupled to the computer system. The host CPU executing code and
data from the host memory thus comprises a means for downloading
graphical code into an embedded implementation according to the
steps described below.
[0069] The embedded system comprised in the host computer 102
preferably includes a memory media which stores a real-time kernel
providing basic OS services, as well as a graphical programming
system run-time engine for real-time execution of compiled
graphical programs. The embedded CPU executing code and data from
the embedded memory thus comprises a means for executing graphical
code in an embedded real-time system according to the steps
described below.
[0070] The instruments or devices in FIGS. 1 and 1A are controlled
by graphical software programs, optionally a portion of which
execute on the CPU of the computer 102, and at least a portion of
which are downloaded to the embedded system for execution. The
graphical software programs which perform data acquisition,
analysis and/or presentation, e.g., for instrumentation control or
industrial automation, are referred to as virtual instruments.
[0071] In the preferred embodiment, the present invention utilizes
the LabVIEW or BridgeVIEW graphical programming systems, hereafter
collectively referred to as LabVIEW, available from National
Instruments. Also, in the preferred embodiment, the term "LabVIEW"
is intended to include graphical programming systems which include
G programming functionality, i.e., which include at least a portion
of LabVIEW graphical programming functionality, including the
BridgeVIEW graphical programming system.
[0072] Also, the term "graphical programming system" is intended to
include any of various types of systems which are used to develop
or create graphical code or graphical programs, including LabVIEW
and BridgeVIEW from National Instruments, Visual Designer from
Intelligent Instrumentation, Hewlett-Packard's VEE (Visual
Engineering Environment), Snap-Master by HEM Data Corporation,
DASYLab by DasyTec, and GFS DiaDem, among others.
[0073] Although in the preferred embodiment the graphical programs
and embedded system are involved with data acquisition/generation,
analysis, and/or display, and for controlling or modeling
instrumentation or industrial automation hardware, it is noted that
the present invention can be used to create embedded
implementations of graphical programs for a plethora of
applications and are not limited to instrumentation or industrial
automation applications. In other words, FIGS. 1 and 1A are
exemplary only, and the present invention may be used in any of
various types of systems. Thus, the system and method of the
present invention is operable for creating embedded implementations
of graphical programs or graphical code for any of various types of
applications, including general purpose software applications such
as word processing, spreadsheets, network control, games, etc.
[0074] FIG. 2--Computer Block Diagram
[0075] Referring now to FIG. 2, a block diagram of the host
computer 102 (of FIG. 1) is shown. The elements of a computer not
necessary to understand the operation of the present invention have
been omitted for simplicity. The computer 102 includes at least one
central processing unit or CPU 160 which is coupled to a processor
or host bus 162. The CPU 160 may be any of various types, including
an x86 processor, a PowerPC processor, a CPU from the Motorola
family of processors, a CPU from the SPARC family of RISC
processors, as well as others. Main memory 166 is coupled to the
host bus 162 by means of memory controller 164. The main memory 166
stores a graphical programming system. The main memory 166 also
stores operating system software as well as the software for
operation of the computer system, as well known to those skilled in
the art. The instrumentation control software will be discussed in
more detail below.
[0076] The host bus 162 is coupled to an expansion or input/output
bus 170 by means of a bus controller 168 or bus bridge logic. The
expansion bus 170 is preferably the PCI (Peripheral Component
Interconnect) expansion bus, although other bus types can be used.
The expansion bus 170 includes slots for various devices such as
the data acquisition board 114 (of FIG. 1), a GPIB interface card
122 which provides a GPIB bus interface to the GPIB instrument 112
(of FIG. 1), and a VXI or MXI bus card 186 coupled to the VXI
chassis 116 for receiving VXI instruments. The computer 102 further
comprises a video display subsystem 180 and hard drive 182 coupled
to the expansion bus 170.
[0077] One or more of the interface cards or devices coupled to the
expansion bus, such as the DAQ card 114, the GPIB interface card
122, the GPIB instrument 112, or the VXI or MXI bus card 186
comprises an embedded system comprising an embedded CPU and
embedded memory.
[0078] In an alternate embodiment, the embedded system is a
stand-alone device, and may be coupled as a node to a network. In
this embodiment, the host computer 102 is also connected as a node
on the network. The embedded system may take various
configurations, as desired.
[0079] FIG. 3--Embedded System Diagram
[0080] Referring now to FIG. 3, a block diagram illustrating an
interface card comprising an embedded system according to the
present invention is shown. It is noted that FIG. 3 is exemplary
only, and an interface card or device comprising an embedded system
according to the present invention may have various architectures
or forms, as desired. The interface card illustrated in FIG. 3 is
the DAQ interface card 114 shown in either of FIGS. 1, 1A, or 2.
However, as noted above, the reconfigurable hardware may be
included on any of the various devices shown in FIGS. 1 or 1A, or
on other devices, as desired.
[0081] As shown, the interface card 114 includes an I/O connector
202 which is coupled for receiving signals. In the embodiments of
FIGS. 1 and 1A, the I/O connector 202 presents analog and/or
digital connections for receiving/providing analog or digital
signals. The I/O connector 202 is adapted for coupling to SCXI
conditioning logic 124 and 126, or is adapted to be coupled
directly to a unit under test 130 or process 160.
[0082] The interface card 114 also dedicated logic 204 for
performing a specific function. In the embodiment of FIG. 3, the
interface card 114 includes data acquisition (DAQ) logic 204. As
shown, the data acquisition logic 204 comprises analog to digital
(A/D) converters, digital to analog (D/A) converters, timer
counters (TC) and signal conditioning (SC) logic as shown. The DAQ
logic 204 provides the data acquisition functionality of the DAQ
card 114. In the preferred embodiment, the dedicated logic 204 is
comprised on a daughter card which is inserted into a connector on
the main card, wherein the main card includes the other components
shown in FIG. 3.
[0083] According to the preferred embodiment of the invention, the
interface card 114 includes a dedicated on-board microprocessor 212
and memory 214, referred to as an embedded processor and embedded
memory, respectively. This enables a portion of the graphical
program to be compiled into machine language for storage in the
memory 214 and execution by the microprocessor 212. As noted above,
the embedded memory 214 stores a kernel providing basic OS
services, as well as a graphical programming system run-time engine
for real-time execution of compiled graphical programs. The
embedded memory 214 is also operable to receive and store a portion
or all of a compiled graphical program for execution in the
embedded system. The embedded CPU 212 executes code and data from
the embedded memory 214 to implement at least a portion of a
virtual instrumentation or industrial automation function.
[0084] As shown, the interface card 114 further includes bus
interface logic 216 and a control/data bus 218. In the preferred
embodiment, the interface card 114 is a PCI bus-compliant interface
card adapted for coupling to the PCI bus of the host computer 102,
or adapted for coupling to a PXI (PCI extensions for
Instrumentation) bus. The bus interface logic 216 and the
control/data bus 218 thus present a PCI or PXI interface.
[0085] The interface card 114 also includes local bus interface
logic 208. In the preferred embodiment, the local bus interface
logic 208 presents a RTSI (Real Time System Integration) bus for
routing timing and trigger signals between the interface card 114
and one or more other devices or cards.
[0086] In the embodiment of FIG. 3A, the interface card 114 further
includes a programmable hardware element or programmable processor
206. In the preferred embodiment, the programmable hardware 206
comprises a field programmable gate array (FPGA) such as those
available from Xilinx, Altera, etc. The programmable hardware
element 206 is coupled to the DAQ logic 204 and is also coupled to
the local bus interface 208. Thus graphical programs can be created
on the computer 102, or on another computer in a networked system,
and, in this embodiment, one or more graphical programs can be
converted into embedded hardware implementations, and at least a
portion of one or more graphical programs can be converted into
hardware implementation forms for execution in the FPGA 206.
[0087] Thus, in one embodiment, after one or more graphical
programs have been created, one or more of the graphical programs
are compiled for execution on the CPU 212 and execute locally on
the interface card 114 via the CPU 212 and memory 214, and at least
a portion of a second graphical program is translated or converted
into a hardware executable format and downloaded to the FPGA 206
for hardware implementation.
[0088] FIG. 4--Initializing the Embedded System
[0089] Referring now to FIG. 4, a high level flowchart diagram is
shown illustrating operation of initializing the embedded system.
In the preferred embodiment, the embedded system does not include a
non-volatile media, such as a hard disk, for storing software
programs such as the OS kernel or the embedded graphical
programming system. Since an operating system and application
programs typically reside on a hard drive or non-volatile media of
a computer system, and a computer system typically `boots` the
operating system from the hard drive, its absence means that an
alternative method of booting needs to present. FIG. 4 illustrates
loading of the various software elements comprised in the embedded
system from the host computer onto the embedded system. It is noted
that various of the steps in the flowcharts below can occur
concurrently or in different orders.
[0090] As shown, in step 402 the kernel or basic operating system
is loaded onto the embedded system. In step 404 the embedded
graphical programming system and various configuration information
are loaded onto the embedded system. In the preferred embodiment,
the embedded graphical programming system is embedded LabVIEW. In
step 406 various software drivers and/or configuration utilities
are loaded onto the embedded system.
[0091] Thus, once the embedded system is initialized, the embedded
system includes a kernel, an embedded graphical programming
execution system, e.g., embedded LabVIEW, and any necessary device
drivers. In the preferred embodiment, the kernel is the Phar Lap
kernel RTOS (real time operating system) available from Phar
Lap.
[0092] FIGS. 5A and 5B--Initializing the Embedded System
[0093] Referring now to FIGS. 5A and 5B, a more detailed flowchart
is shown illustrating operation of the flowchart of FIG. 4. It is
noted that FIGS. 5A and 5B collectively illustrate two separate
parallel flowcharts, a first flowchart illustrating operations of
the host computer 102 (steps 422-430), and a second flowchart
illustrating operations of the embedded system (steps 442-460).
Unless designated with arrows, it is noted that various steps in
each of the two flowcharts can occur in various orders and/or
simultaneously, as desired.
[0094] As shown, in step 420 power is provided to the computer
system 102 and to the embedded system. In response, the host
computer 102 and the embedded system perform the following
operations. In step 422 the host computer 102 boots. This comprises
the host computer 102 performing boot operations as is normally
done in computer systems. In step 424 the host computer 102
executes a loader application which is operable to load various
elements onto the embedded system. The loader application causes
the host computer 102 to wait for a request from the embedded
system.
[0095] Independently of steps 422 and 424, in step 442 the
interface card 114 comprising the embedded system also boots up.
This involves the embedded CPU 212 on the embedded system executing
the BIOS (basic input/output system) from ROM comprised on the
interface card 114.
[0096] After the interface card boots up in step 442, in step 444
the embedded system executes BIOS extension software according to
the present invention. Thus, when the embedded system boots up, the
embedded system executes the BIOS code in the read-only memory
(ROM), as is typical in any computer system. The BIOS code searches
for any BIOS extension program present in memory and executes any
BIOS extension program that it finds. Taking advantage of this
feature, a BIOS extension program is stored in the ROM, wherein the
BIOS extension software is provided in addition to the normal BIOS
software. The BIOS extension software is a loader program that
causes the embedded system to request a load image from the host
computer 102. More specifically, the BIOS extension software causes
the embedded CPU 212 to set one or more bits in the shared memory
on the embedded system which causes a request to be made to receive
a load image from the host computer.
[0097] In response to this request for the load image by the
embedded system in step 444, in step 426 the host computer 102
receives the request and operates to transfer the load image from
system memory 166 to the shared memory 230 on the embedded system.
In step 446 the embedded system receives the load image from the
shared memory 230. This transfer utilizes a shared memory protocol
which is described further below. The host computer 102 operates to
transfer the load image in a plurality of iterations using block
transfers. Thus it is noted that steps 426 and 446 iteratively
execute a plurality of times in order to transfer portions of the
load image from the host computer to the embedded system. This is
primarily due to the limited size of the buffers in the shared
memory 230 and thus numerous transfers are required. In other
words, due to the limited size of the shared memory 230, the host
CPU 160 operates to transfer the load image in sequential block
transfers using the shared memory protocol.
[0098] After the embedded system has received the load image from
the shared memory 230 and stored the load image in its memory 214,
in step 448 the embedded CPU 212 executes the load image to load
the kernel into its memory 214. In addition to the kernel being
loaded into the memory 214, a small program is also loaded which,
when executed, causes the embedded system to request that the
embedded graphical programming system, e.g., embedded LabVIEW, be
transferred to the embedded system. In response to this request in
step 450, in step 428 the host transfers the embedded graphical
program execution engine, e.g., embedded LabVIEW to the shared
memory 230. In step 452 the embedded system receives the embedded
graphical program execution engine from the shared memory 230. This
transfer preferably utilizes the shared memory protocol mentioned
above and described further below. In step 454 the embedded system
loads the embedded graphical program execution engine into its
memory 214.
[0099] In step 456 the embedded system requests software drivers
from the host system. In response to this request, in step 430 the
host transfers the drivers to the shared memory 230, and in step
458 the embedded system receives the drivers. This transfer also
preferably utilizes the shared memory protocol mentioned above and
described further below. For example, where the embedded system
resides on the DAQ card 114, data acquisition drivers are
preferably loaded on the system, preferably the NI-DAQ drivers
available from National Instruments. In alternate embodiments where
the embedded system is a different type of device, such as a GPIB
interface card, or an image acquisition device, then the respective
driver is loaded onto the system.
[0100] Any device drivers or configuration utilities which are
downloaded preferably make use of an OS independent API. The actual
device driver is preferably a Phar Lap DLL.
[0101] For more information on an alternate embodiment of booting
the embedded system, please see related co-pending application Ser.
No. 08/870,966 titled "System and Method for Enabling a Target
Computer to Use Storage Resources of a Host Computer" filed Jun. 6,
1997, whose inventor is Vivek Gupta, which is assigned to National
Instruments Corporation, and which issued as U.S. Pat. No.
5,887,164 on Mar. 23, 1999.
[0102] Embedded Graphical Programming System (Embedded LabVIEW)
[0103] The following comprises a list of the major components in
the host LabVIEW graphical programming system. The components which
are marked ** are included in Embedded LabVIEW. The components
which are not marked ** are not included in Embedded LabVIEW.
[0104] 1. Editor Panel, Block Diagram, Data Manager, find, Diff,
Project Builder, Hierarchy, Load, Save, undo, . . . etc
[0105] 2. Compiler Code Generation
[0106] 3. Linker**
[0107] 4. Kernel **
[0108] 5. Execution Engine ** Debugging Tools/Mechanism **
[0109] Break Points **
[0110] single stepping **
[0111] Probe **
[0112] 6. Type/Unit Propagation
[0113] 7. Server** Application Server** TCP Server **
[0114] 8. Front Panel Protocol ** (New Component added in LabVIEW
to support ELV)
[0115] Managers:
[0116] 9. Memory**
[0117] 10. Configuration **
[0118] 11. Color
[0119] 12. Connection**
[0120] 13. Device **
[0121] 14. Draw
[0122] 15. Drag N Drop
[0123] 16. External Code **
[0124] 17. File **
[0125] 18. Image
[0126] 19. Menu
[0127] 20. Resource
[0128] 21. Scroll
[0129] 22. Support**
[0130] 23. Text
[0131] 24. Font
[0132] 25. Thread**
[0133] 26. Window
[0134] FIG. 6--Creation and Execution of a Graphical Program.
[0135] Referring now to FIG. 6, a flowchart diagram is shown
illustrating operations where by the user creates a graphical
program for execution in an embedded system according to the
present invention. As shown, in step 502 the user launches the host
graphical programming system on the host computer 102. In other
words, in response to user input, the host computer system 102
launches the executable of the host graphical programming system to
run the graphical programming system on the host computer 102.
[0136] In step 504 the user selects an execution engine for
execution of the graphical program. In other words, in step 504 the
computer system 102 receives and stores user input regarding which
execution engine is to execute the graphical program. In the
embodiment shown in FIG. 3, two execution engines are comprised in
the system, one being in the host computer 102 associated with the
main graphical programming system, and a second associated with the
embedded graphical programming system comprised in the embedded
system. It is noted that a plurality of embedded systems may be
coupled to the host computer 102, either directly or through a
network. It is also noted that the execution engine can be selected
prior to launching the graphical programming system or after a
graphical program has been created or opened.
[0137] The user can select the execution engine in various manners.
In one embodiment, in step 504 the host computer 102 displays a
dialog box regarding selection of an execution engine. The host
computer 102 displays the dialog box in response to a user
preference setting in a preferences dialog that indicates that a
dialog box should be displayed to enable the user to select the
execution engine. Thus, in this embodiment, the preferences menu
includes a setting which allows the user to select whether to
display the dialog box or not. This is used to disable the display
of the dialog box, for example, when the user is primarily using
the host graphical programming system to create host applications,
and the user does not wish to be bothered with having to provide
input to this dialog box every time the graphical programming
system is launched. In one embodiment, if the user launches LabVIEW
through a command line, the user can include an argument specifying
the desired execution engine. Alternatively, the user can create an
icon representing the graphical programming system which
automatically specifies one of the execution engines.
[0138] After the user has launched the host graphical programming
system, e.g. host LabVIEW, in step 502 and has selected the desired
execution engine in step 504, in step 506 the user creates or opens
a graphical program. Step 506 presumes that a graphical programming
development system is stored in the memory of the host computer
system for creation of graphical programs. In the preferred
embodiment, the graphical programming system is the LabVIEW
graphical programming system available from National Instruments.
In this system, the user creates the graphical program in a
graphical program panel, referred to as a block diagram window and
also creates a user interface in a graphical front panel. In the
preferred embodiment, the graphical program comprises a graphical
data flow diagram which specifies functionality of the program to
be performed. This graphical data flow diagram is directly
compilable into machine language code for execution on the computer
system 102. For more information on creating a graphical program or
virtual instrument (VI) in LabVIEW, please see the above patent
applications. The host graphical programming system thus provides a
seamless environment in which the user can develop an embedded
application using high level graphical programming techniques.
[0139] After the user has created or opened a graphical program in
step 506, in steps 508 and 510 the user compiles the graphical
program, i.e., user input is received indicating that the graphical
program should be compiled. In the preferred embodiment of the
LabVIEW graphical programming system, the user selects the run
button in step 508, which automatically causes the graphical
program to be compiled into machine language in step 510. Thus in
step 510 the host LabVIEW compiler compiles the graphical
program.
[0140] Once the graphical program has been compiled into machine
language in step 510, the system determines whether the machine
language or executable portion of the program is to run on the host
computer or on the embedded computer. In other words, the system
determines which execution engine has been selected by the user. If
the host computer 102 has been selected by the user, then the
machine language or compiled version of the graphical program is
executed in the host computer 102, i.e., on the host CPU 160, as is
normally done in LabVIEW.
[0141] If the user has selected the embedded execution engine, then
in step 522 the host computer 102 operates to transfer the machine
language code corresponding to the graphical program to the
embedded system to begin execution of the compiled code on the
embedded system.
[0142] FIG. 7--Beginning Execution of Compiled Code on Embedded
System
[0143] Referring now to FIG. 7, a flowchart diagram is shown
illustrating the steps performed in step 522 of FIG. 6. As shown,
in order to begin execution of the compiled code on the embedded
system, the following steps are performed. First, in step 542, the
host computer 102 operates to transfer the machine language code
corresponding to the graphical program to the embedded system, this
time using a higher level front panel protocol. This higher level
front panel protocol preferably utilizes an underlying data
transfer protocol. In the present embodiment where the embedded
system is the interface card 114, the front panel protocol sits on
top of the shared memory protocol. In a networked embodiment, the
front panel protocol utilizes the underlying network protocol, such
as Ethernet.
[0144] The front panel protocol operates to provide further
information regarding the identity of the data being transferred.
This allows more intelligent transfer of the various components of
the machine language code forming the graphical program or VI. This
allows the embedded system to properly identify and configure the
compiled graphical program in its memory for execution. It is noted
that, if the compiled graphical program has been previously
transferred and stored in the embedded system, then the transfer in
step 542 is not required.
[0145] Referring now to FIG. 9, in the preferred embodiment where
the LabVIEW graphical programming system is used, a graphical
program comprises the following components. As shown, a graphical
program comprises front panel and block diagram source code
portions, linker information, executable code, and data. In the
preferred embodiment, the front panel and block diagram source code
remains in the host computer 102, and the linker information,
executable code, and data are transferred to the embedded system.
The executable code or machine language code includes data
structures which represent the controls and indicators that are to
be displayed on the front panel. However, as discussed further
below, the actual code which operates to display these controls and
indicators and display and update data within these controls and
indicators, referred to as the editor portion, is preferably
comprised in the host graphical programming system executing on the
host computer 102.
[0146] Once the machine language representing the VI has been
transferred to the memory in the embedded system in step 542, in
step 544 the host computer 102 transfers a request to the embedded
system to execute the compiled graphical program. Here it is noted
that in various configurations, such as in a network, various host
devices can request the embedded system to execute a respective
graphical program or VI. In order to prevent a race condition in
this instance, in step 544 the host computer 102 transfers a
request to the embedded system to execute the compiled graphical
program.
[0147] In response to this request, in step 546 the embedded system
determines if the rights to execution of the compiled graphical
program have already been given to a prior requester. If so, then
in step 552 the embedded system returns a message to the host
computer 102 that the compiled graphical program is already
executing for another requester. If the rights to execution of the
compiled graphical program have not already been given to a prior
requester in step 546, then in step 548 the embedded system
executes the graphical program.
[0148] Embedded System Execution of the Graphical Program
[0149] As noted above, in step 548 the embedded system executes the
graphical program, i.e., the embedded CPU 212 executes the machine
language to implement the graphical program inside the embedded
system. FIG. 8 is a simplified diagram illustrating execution of
the graphical program in the embedded system. As shown, in step 602
the embedded system executes block diagram portion, and in step 604
the host system executes the front panel portion of the graphical
program
[0150] When a graphical program or VI is executed in the embedded
system, execution of the block diagram portion of computation
portion proceeds in a similar manner as if the graphical program
were being executed inside the host computer 102. However, for
front panel operation, i.e., I/O to/from the graphical program, the
actual code for implementing the front panel display resides in the
host computer 102.
[0151] In the preferred embodiment, when a graphical program is to
be executed on the embedded system, the computation portion of the
VI or graphical program is compiled into machine language and is
downloaded and executed on the embedded system. In addition, the
machine language code includes structures which represent the
controls and indicators that are to be displayed on the front panel
of the graphical program. However, the actual code which operates
to display these controls and indicators and display and update
data within these controls and indicators, referred to as the
editor portion, is comprised in the graphical programming system
which executes on the host computer 102 and is not part of the
embedded LabVIEW comprised on the embedded system. Therefore the
computation or block diagram portion of the graphical program
executes on the embedded system. However, all I/O, either user
provided input or output required to be displayed on the front
panel, is handled by the editor executing on the host system 102.
This is illustrated conceptually in FIG. 10, whereby the graphical
program executes on the embedded system, and the host LabVIEW
implements the user interface or front panel for the graphical
program, using the shared memory for communication.
[0152] Thus for user I/O, when the user provides input to a
control, the host computer 102 performs the display operations and
is required to transfer the input data to the embedded system using
the front panel protocol and the shared memory as described above.
In a similar manner, when execution of the compiled graphical
program in the embedded system generates output which is necessary
to be displayed on the front panel of the VI, then the embedded
system utilizes the front panel protocol and the shared memory to
transfer the output to the LabVIEW editor executing on the host
computer 102, which operates to display the data on the display
screen. Thus, when a graphical program or VI is executing on the
embedded system, the user can operate/view the controls and
indicators of the graphical program on the display of the host
computer as if the graphical program were executing directly on the
host system.
[0153] In one embodiment, the user can input a selection which
prevents display of updates of output data in order for increased
speed and efficiency in the real time embedded system.
[0154] The present invention also allows programmatic control of
graphical programs or VIs in embedded LabVIEW from host LabVIEW. In
the preferred embodiment, the host and embedded LabVIEW programs
each include a set of VIs or graphical programs and/or a C library,
that to allow programmatic control of each program. These VIs or
graphical programs on each of the host and embedded LabVIEW can
communicate, such as by accessing the reserved portion of shared
memory or using a network protocol. This enables a user to build an
application in which a portion runs on the host computer 102 and a
portion runs on the embedded system. For example, the user can
create an application in which the user interface/data logger VIs
execute on the host computer 102 and control/data acquisition VIs
execute on embedded LabVIEW. The host LabVIEW can thus act, for
example, as an independent application communicating with embedded
LabVIEW, such as through the shared memory.
[0155] The embedded system provides more deterministic and/or real
time performance for execution of applications. The embedded
graphical programming system, e.g., embedded LabVIEW, provides
determinism due to the following. First, embedded LabVIEW has no
direct user interface. Also, there is no interference in program
execution, such as from disk caching, and no overhead, e.g., driver
call overhead, from the OS. Embedded LabVIEW is also the only
application running in the system. Finally, embedded LabVIEW is
running on top of a real-time operating system, as opposed to a
desktop non-real-time system.
[0156] Execution of Attribute Nodes
[0157] It is noted that the embedded system executes a graphical
program somewhat differently for certain constructs comprised
within a graphical program. For example, the LabVIEW graphical
programming system includes attribute nodes which are placed in a
program to allow a user to programmatically control front panel
objects, such as controls and indicators. When the execution engine
in the embedded system arrives upon execution of an attribute node,
the execution system recognizes that an attribute node is
substantially solely involved with the program changing values or
other information on front panel objects, such as controls or
indicators. In this case, it is impossible for the execution system
to execute the attribute node because the attribute node is
intricately involved with changing parameters or attributes
associated with front panel objects, and this code resides solely
on the host computer 102. Therefore, in the preferred embodiment,
for attribute nodes, the execution engine in the embedded system
operates to transfer a pointer to where the code execution should
begin as well as the necessary data to perform the operations. The
host computer 102 can then execute this portion of the code. The
embedded system only transfers a pointer and the necessary data to
the host, since the code necessary to execute the attribute node
already resides on the host. When the host computer has completed
execution of this portion of code associated with the attribute
node, the host computer 102 operates to modify the front panel
accordingly and provides any results to the execution engine for it
to use in execution of the remainder of the graphical program.
[0158] Shared Memory Protocol
[0159] In the preferred embodiment where the embedded system is an
interface card, the host computer 102 and the embedded system each
include a Shared Memory Communication (SMC) Manager which
implements the shared memory protocol. The SMC Manager is a simple,
low level driver that provides the ability to send and receive
streams of bytes through the shared memory 230.
[0160] The SMC Manager comprises two layers: A top layer that
presents a Winsock like API, and a Physical layer that accesses the
shared memory. The SMC Manager provides the most basic services
(read, write, callback) to its client. The top (Winsock) layer is
preferably simplistic due to the use of shared memory, e.g.,
because the top layer does not have to handle lost packets or
packets arriving out of sequence. The physical layer carries out
the actual reading and writing to shared memory.
[0161] The Winsock layer is a very thin veneer over the physical
layer. Thus, in the Shared Memory Manager, the physical layer
performs most of the work. When a LAN is supported as a physical
medium, the Winsock layer expands to include the TCP protocol, and
an IP layer is inserted between the Winsock layer and the physical
layer.
[0162] The SMC Manager provides a connection between two entities
so that they can exchange data. The two entities will usually
reside in two different systems (e.g. one on the host PC and one on
the embedded system, e.g., the intelligent DAQ card). Thus, each
system has its own SMC Manager. The SMC protocol is preferably a
peer-to-peer protocol and there is no master/slave hierarchy. The
SMC managers are referred to below as host and slave SMC managers
for convenience.
[0163] The shared memory is subdivided into a number of areas. Part
of the shared memory is reserved for register access, and the rest
is dedicated to the shared memory protocol. The shared memory is
structured as shown in FIG. 12.
[0164] 1. Establishing Connection
[0165] The shared memory block includes two connection vectors--one
for the host SMC and one for the slave SMC--that indicate which
connection is desired to be open. Each bit in the vector
corresponds to a connection number. The bits in the connection
vector are set when the open function with the corresponding
connection number is called. The bits are reset when the close
function is called. A connection is established when the
corresponding bits in both the host and slave connection vector are
set.
[0166] It is noted that the connection vectors are not a perfectly
reliable way to determine that a connection is valid, e.g., one
side could reboot without resetting the connections.
[0167] The number of connections that can be opened is limited by
the number of bits used for the connection vectors. In the
preferred embodiment, 32 connections are available.
[0168] 2. Data Transfer
[0169] The data transfer scheme uses two unidirectional channels.
Each channel is structured as shown in FIG. 13. If the sender owns
the channel, it can move data to the data area, set the length and
transfer ownership of the channel to the receiver. When the
receiver obtains the ownership of the channel, it can get transfer
data out of the channel, and when it's done, it can transfer the
ownership back to the sender. The receiver cannot read the data
area until it has ownership, and the sender cannot write to the
data area until it has the ownership.
[0170] 3. User Interface Considerations
[0171] There is no direct user interface to the SMC Manager.
[0172] 4. Alternate Embodiment
[0173] In an alternate embodiment, bi-directional channels are
used. Bi-directional channels may be used because the scheme of two
uni-directional data channels may not lead to the most efficient
use of resources. For example, if one side is sending small packets
and the other is sending large packets, then one data channel is
under utilized and the other is overburdened. Bi-directional
channels remedy this problem. However, bi-directional channels are
more complicated, and having to contend for the token may cause
delays itself. FIG. 14 illustrates the structure of the shared
memory bank using bi-directional channels.
[0174] FIG. 15 the data channel structure. Each data channel
comprises a data area and a control area. The data area is used for
the actual data transfers, while the control area is used for
house-keeping and connection management.
[0175] Since the two sides of the connection cannot both write to
the data area simultaneously, tokens are used to arbitrate who has
read/write privilege to different fields of the shared memory
block. FIG. 16 illustrates the privileges of token owners and
non-owners. Only one side (the token owner) can read or write the
data area at any time. The control area permits concurrent
write/write (not to the same location), read/write, read/read
operations-subject to limitations of privileges.
[0176] The table of FIG. 16 summarizes the privileges of token
owners and non-owners with regards to the different fields in the
shared memory block. As shown, only the token owner can change the
Token Owner field (i.e. to pass the token to the other side). The
non-owner obviously cannot change this field. The SMC Manager can
always read and write to it's own Token Request flag. However, it
only makes sense to change the request flag to true if it doesn't
have the token (in order to request for it) and change the flag to
false if it already has the token. The token owner has to be able
to read the Token Request flag of the other side, so it can pass
the token to the other side if requested. The non-owner cannot read
the Token Request flag because it has no token to pass. The
non-owner cannot read the data area because the data area might be
in a inconsistent state (e.g. the length field is wrong). The token
owner will make sure the data area is in a consistent state before
passing the token.
[0177] It is noted that there is not a case where both sides have
write privilege to the same field at any time. So even while
concurrent writes are permitted in the control area, there will not
be concurrent writes to the same field or location.
[0178] 5. Basic Operation
[0179] If the token owner needs to send data, it writes the data to
the data area and passes the token to the other side. Once the
other side has the token, it can read out the data from the data
area.
[0180] If the non-owner needs to send data, it needs to wait until
it has the token--which it can obtain in one of two ways. One, if
the other side sends it data, the token will be passed along with
the data. Otherwise, the non-owner can "request" the token by
setting the Token Request flag. Once the other side sees this
request, it will pass the token (with or without data).
[0181] 6. Flow Control
[0182] When the SMC Manager reads data from the shared memory, it
stores the data in a read buffer. Each connection preferably has
its own read buffer. When the client calls the read function the
client obtains the data out of the read buffer. When a read buffer
is full, the SMC Manager discards data in the shared memory block
without transferring it to the read buffer (to free the shared
memory for further transactions). Clients also have a mechanism to
detect loss of data and compensate for it by re-transmission.
[0183] Front Panel Protocol
[0184] The front panel protocol is a high level communication
protocol which is used by the host LabVIEW and embedded LabVIEW.
The host LabVIEW and embedded LabVIEW communicate with each other
using the front panel protocol. The front panel protocol defines a
format of data and commands that are transmitted back and forth to
enable transmission of graphical program objects, software
components and other data between host LabVIEW and embedded
LabVIEW.
[0185] For an interface card comprised in the computer system, the
front panel protocol uses the shared memory protocol described
above in performing the actual transfers. The front panel protocol
uses the Winsock API and effectively sits on top of the Winsock
API. In an alternate embodiment where a networked environment is
used, a different underlying protocol is used, such as Ethernet.
The front panel protocol transmits data as a sequence of packets,
wherein each packet is a collection of data sent as a single
message
[0186] During execution of a graphical program on the embedded
system, the front panel protocol defines the format of data and
commands that are transmitted back and forth to provide proxy
controls and indicators on the host for the graphical program
executing on the embedded system. As mentioned above, during
execution of a compiled graphical program on the embedded system,
the host CPU executes front panel display code to display on the
screen the graphical front panel of the graphical program. The host
LabVIEW and embedded LabVIEW use the front panel protocol to
communicate I/O data back and forth to accomplish this split
execution. The host graphical programming system or host LabVIEW
thus provides the user interface for graphical programs executing
on the embedded system. The host LabVIEW thus essentially acts as
the front panel "browser" for embedded LabVIEW applications.
[0187] The front panel protocol is also used for downloading of
graphical programs or VIs to the embedded system. Using the front
panel protocol, the host LabVIEW operates to download a graphical
program or VI by breaking the graphical program into pieces and
sending them with any required information so that the graphical
program can be reconstructed by the embedded system.
[0188] Further, as described below, the front panel protocol is
used for single stepping/debugging a graphical program executing on
the embedded system.
[0189] As noted above, the host LabVIEW can also act as an
independent application communicating with embedded LabVIEW through
the shared memory, preferably using the shared memory protocol, or
the front panel protocol.
[0190] Debugging a Graphical Program Executing on the Embedded
System
[0191] The present invention provides the user the ability to debug
a graphical program application which is executing on the embedded
system, wherein the debugging is performed using graphical front
panels and other graphical information displayed on the display
screen of the host computer. Further, the user is able to debug a
graphical program application which is executing on the embedded
system by opening and viewing the block diagram of the graphical
program application on the host computer using the host LabVIEW.
Thus, as the compiled graphical program executes on the embedded
system, the host computer displays the block diagram and/or front
panel for debugging purposes.
[0192] The user can thus use various familiar graphical programming
debugging techniques for a graphical program executing on the
embedded system, including single stepping through the graphical
program, execution highlighting, setting break points in the
graphical program, and remote probing of nodes in the graphical
program. FIG. 11 conceptually illustrates the front panel displayed
on the host computer 102 being used for debugging a graphical
program executing on the embedded system.
[0193] The embedded system provides data regarding graphical
program execution to the host computer, and the host computer
displays this information for debugging purposes. Further, the user
can enter input, such as selected nodes to be probed or enabling
the next node to execute in single-step mode, and this information
is provided to the embedded system to cause the desired execution.
Thus, the user can use the host computer CPU and display screen for
displaying the front panel and/or block diagram for debugging
purposes for a graphical program executing on the embedded
system.
[0194] Execution highlighting is used for debugging purposes to
view an animation of the execution of the VI block diagram.. With
execution highlighting, the movement of data from one node to
another is marked by objects or bubbles moving along the wires.
When execution highlighting is enabled for a graphical program
executing on the embedded system according to the present
invention, as the graphical program executes on the embedded
system, the embedded system provides execution status data to the
host computer to enable the host computer to display bubbles moving
along the wires of the block diagram, wherein the bubbles represent
execution of the graphical program on the embedded system.
[0195] Execution highlighting is commonly used with single-step
mode to gain an understanding of how data flows through nodes in
the graphical program. In single-stepping mode, the user presses a
step button to proceed to execution of a subsequent node in the
graphical program. Also, during execution of a current node, the
next node to be executed blinks rapidly. According to the present
invention, the embedded system provides execution status data to
the host computer informing the host computer as to which node is
currently being executed, and to enable the host computer to blink
the next node to be executed. Also, as the user enters input to
proceed to execution of the next node, the host computer provides
this user input to the embedded system to direct the embedded
system to execute the next node in the graphical program.
[0196] DLL Nodes
[0197] The present invention includes a mechanism for embedded
LabVIEW to load DLLs and to invoke or call functions in DLLs. These
DLLs may be generated by the native development tools (specifically
the linker) provided by the real-time operating system used in the
embedded system, or by development tools used for desktop computer
systems (e.g. Microsoft Visual C++). In the latter case, because
the DLLs generated by desktop development tools are not intended to
be used in real-time operating systems, some modification or
`patching` is necessary to make the DLL compatible with the
embedded system. The importance of having the ability to use DLLs
generated by desktop development tools is for user convenience,
such that the user is not required to purchase any additional
real-time development tools (specifically the linker) in order to
take advantage of the flexibility provided by DLLs.
[0198] DLLs are normally loaded from disks or other non-volatile
media. Because of the absence of such non-volatile media in the
embedded system, an alternative method is required. The loading of
DLLs is somewhat similar to the process of initial booting--the
embedded system requests the DLL from the host system, using the
shared memory protocol as the conduit. An application on the host
system reads the requested DLL from its hard disk and supplies the
DLL to the embedded system.
[0199] Loading and Relocating CINs
[0200] The present invention includes a mechanism for loading and
relocating code interface nodes (CINs).
[0201] Error Reporting
[0202] In the preferred embodiment, errors generated during
execution of the graphical program on the embedded system are
provided to the host system for display on the screen.
[0203] Resource Management
[0204] The present invention includes a method for defining and
ensuring behavior of LabVIEW when a VI requests a resource that
does not exist. MORE The present invention also intelligently
handles File IO, Front Panel Attributes, Networking
[0205] New Primitives
[0206] The present invention includes new basic primitives which
allow the user to build deterministic control loops. For example,
one new primitive allows a user to specify skew in the "Wait for
multiple ms" primitive.
[0207] Although the system and method of the present invention has
been described in connection with the preferred embodiment, it is
not intended to be limited to the specific form set forth herein,
but on the contrary, it is intended to cover such alternatives,
modifications, and equivalents, as can be reasonably included
within the spirit and scope of the invention as defined by the
appended claims.
* * * * *