U.S. patent application number 11/801127 was filed with the patent office on 2007-11-01 for system for programmed control of signal input and output to and from cable conductors.
This patent application is currently assigned to Berkeley Process Control, Inc.. Invention is credited to Larry Brasfield, Paul Sagues.
Application Number | 20070255879 11/801127 |
Document ID | / |
Family ID | 38723660 |
Filed Date | 2007-11-01 |
United States Patent
Application |
20070255879 |
Kind Code |
A1 |
Sagues; Paul ; et
al. |
November 1, 2007 |
System for programmed control of signal input and output to and
from cable conductors
Abstract
An input/output module for implementing directions from a
controller for sending and receiving signals to and from devices.
The input/output module includes a microprocessor for communication
with, and receiving programming from the controller. The
input/output module further includes device communication
connectors, each having number of pins, each pin for
interconnection with a cable conductor to a device. The
input/output module has an ASIC for each of the pins, providing a
controlled interface with the corresponding pin. Each ASIC has
interconnection apparatus, selectable by the microprocessor for
providing a particular interface with the pin served by the
ASIC.
Inventors: |
Sagues; Paul; (Ross, CA)
; Brasfield; Larry; (Mercer Island, WA) |
Correspondence
Address: |
PILLSBURY WINTHROP SHAW PITTMAN LLP
P.O. BOX 10500
MCLEAN
VA
22102
US
|
Assignee: |
Berkeley Process Control,
Inc.
Richmond
CA
|
Family ID: |
38723660 |
Appl. No.: |
11/801127 |
Filed: |
May 7, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11296134 |
Dec 6, 2005 |
7216191 |
|
|
11801127 |
May 7, 2007 |
|
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11043296 |
Jan 25, 2005 |
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11296134 |
Dec 6, 2005 |
|
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10071870 |
Feb 8, 2002 |
6892265 |
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11043296 |
Jan 25, 2005 |
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60269129 |
Feb 14, 2001 |
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Current U.S.
Class: |
710/301 |
Current CPC
Class: |
G05B 19/0423 20130101;
G05B 2219/25258 20130101; G05B 2219/1105 20130101; G05B 2219/25321
20130101; G05B 19/054 20130101; G05B 2219/1144 20130101; G05B
2219/1138 20130101; G05B 2219/21116 20130101 |
Class at
Publication: |
710/301 |
International
Class: |
G06F 13/00 20060101
G06F013/00 |
Claims
1. A configurable connectorized system comprising: (a) a module
including (i) a device communication connector apparatus including
a connector for connecting a cable between said module and a
device; and (ii) directing apparatus programmable by a user of said
system and responsive to an input signal from a controller
apparatus for causing said module to place any of a plurality of
signals on any of a plurality of connector pins of said connector,
wherein said directing apparatus includes at least one ASIC
providing a selectable interconnection apparatus to a particular
one of said connector pins.
2-19. (canceled)
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 11/296,134 filed Dec. 6, 2005, which is a
continuation-in-part of U.S. patent application Ser. No. 11/043,296
filed Jan. 25, 2005 (now abandoned), which is a
continuation-in-part of U.S. patent application Ser. No. 10/071,870
filed Feb. 8, 2002 (now U.S. Pat. No. 6,892,265), which claims the
benefit of U.S. Provisional Application Ser. No. 60/269,129 filed
Feb. 14, 2001. The foregoing disclosures are incorporated herein by
reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The present invention relates generally to cabling and
cabling systems, and more particularly to a universal cabling
system wherein the requirement for specific wire interconnections
between first and second devices is accomplished through use of a
programmable I/O module for making connection to the first device,
and directing connections from the first device to selected wires
of a cable for connection to the second device.
[0004] 2. Description of the Prior Art
[0005] Complex electrical/electronic systems often require custom
cable configurations. Cables are usually special configurations for
a particular application. Even in relatively simple systems such as
home audio and small computer systems, a number of different cables
are typically required. In larger applications, such as industrial
control systems, the number of custom cable designs is extensive.
In industrial control systems such as those that run automotive
plants, etc., interaction is required between control apparatus and
sensors and actuators. The apparatus providing the corresponding
connections will be referred to as input and output systems.
Through the output system, the control system can turn on lights,
pumps, valves and other devices. Similarly, through the input
system, the control system can sense the state of a pushbutton,
whether a switch is on or off, or whether a tank is full or how
fast a shaft is turning.
[0006] In prior art control systems, such as a Programmable Logic
Controller (PLC), the user of the control system electrically
connects the sensors and actuators to the input/output systems
using individual wire connections or via connectorized wire
harnesses. A common method of connecting sensors and actuators to
industrial control systems is through the use of individual wire
connections via terminal blocks. Terminal blocks usually employ a
screw-driven clamp. An electrical wire's insulation is removed from
the end, and then the bare wire is slid under the screw-driven
clamp. The screw is then tightened to secure the wire under the
clamp and effect an electrical connection between the wire and the
terminal block. Increasingly, various spring clamps are used to
hold the wire, but these are essentially the same as screw-driven
clamps. FIG. 1 shows how individual wires 10 are connected to the
input and output Modules 12, 14 of a PLC 16 through terminal blocks
18 to three devices, a light bulb 20, a switch 22 and a proximity
switch 24. A proximity switch is a common type of switch that can
detect the presence (typically) of metal, and gives an indication
by interrupting or passing electrical current.
[0007] A disadvantage of the method illustrated in FIG. 1 is that
the terminals 26, 28 on the input or output modules of the PLC 16
are not necessarily conveniently arranged for facilitating easy
connection of a load, such as a light bulb or switch. As a result,
a great deal of custom, hand-wiring must be performed in order to
effect the interconnections. In addition the electricity, from a
supply 30 to power certain actuators and sensors such as the light
bulb or proximity sensor, must be provided on the terminal blocks
18 in order to make connections to the light bulb or switch. In
general, the prior art output Modules 12 and 14 do not supply power
to the load, they only switch the power. The custom wiring design
and implementation illustrated in FIG. 1 significantly adds to the
cost and size of the system.
[0008] Another method of connecting an industrial control system
such as a PLC to a load is via a connectorized wire harness or
cable. FIG. 2 shows one input module 32 and one output module 34
from a PLC 36. The input/output modules 32 and 34 are equipped with
connectors 38 and 40 respectively that allow cables 42 and 44 to be
used to make connection with various sensors and actuators.
Unfortunately, the cable from the input or output module cannot
generally connect directly to the sensor or actuator because the
connectors 38 and 40 on the PLC 36 are rarely configured to accept
a sensor signal or provide the actuator power. For this reason,
FIG. 3 represents the most common method of connecting a PLC to a
sensor or actuator when employing connectors on the PLC. In FIG. 3,
cables 40 from the PLC input 32 and output 34 modules connect to
circuit boards 46 and 48 which contain terminal blocks 50 for
making connections to the control system. Therefore, even when
connectorized cables are employed, the prior art still requires
making connections through use of individual wire connections such
as terminal blocks.
[0009] Making a direct connection between a PLC and a sensor or
actuator without individual wire connections is problematical. An
example situation is when a PLC must be connected to a device that
already is equipped with a connector. The need to connect a PLC to
such a device is very common. A typical device is a mass flow
controller equipped with a connector for connecting signals that
must be connected to the PLC. In this case, the connections are
complicated by the fact that the PLC output module contains only
outputs and the PLC input module contains only inputs, whereas the
mass flow controller connector contains signals that represent both
inputs and outputs. To make matters worse, some of the signals are
discrete--that is, on/off--and some are continuously varying analog
signals. In addition, the mass flow controller also requires
application of a power supply voltage and return/ground to the flow
controller connector.
[0010] In general, prior art methods and apparatus require the use
of custom cable harnesses designed and built to connect the rigid
format of a PLC to the varying formats of the disparate devices
such as mass flow controllers and power supplies. The difficulty of
designing, fabricating and installing complex wire harnesses is so
great that the predominant method of connecting PLC's to sensors
and actuators is via individual wire connections and terminal
blocks.
[0011] FIGS. 4a and 4b show two examples of typical non-standard
cable construction. In FIG. 4a each of wires 52 and 54 connects to
a different pin on connector 56 than on connector 58. The cable of
FIG. 4b has two connectors 60 and 62 on one end and a single
connector 64 on the other end.
SUMMARY
[0012] It is therefore an object of the present invention to
provide a method and apparatus wherein customized connections can
be made using standard cables.
[0013] It is another object of the present invention to provide a
method and apparatus that reduces the cable complexity involved in
making interconnections in control systems.
[0014] It is a further object of the present invention to provide a
method and apparatus for reducing the number of custom designed
cables and individual wire connections in a system.
[0015] It is an object of the present invention to provide a
programmable input/output module for directing signals between
apparatus through standard cables.
[0016] It is another object of the present invention to provide an
improved system for testing cables utilizing programmable
input/output modules.
[0017] It is a still further object of the present invention to
provide an interlock system for a control system that uses
programmable input/output modules and standard cables.
[0018] Briefly, a preferred embodiment of the present invention
includes an input/output module for implementing directions from a
controller for sending and receiving signals to and from devices.
The input/output module includes a microprocessor for communication
with, and receiving programming from the controller. The
input/output module further includes device communication
connectors, each having a number of pins, each pin for
interconnection with a cable conductor to a device. The
input/output module has an application specific integrated circuit
(ASIC) for each of the pins, providing a controlled interface with
the corresponding pin. Each ASIC has a plurality of interconnection
apparatus, each apparatus selectable by the microprocessor for
providing a particular interface with the pin served by the
particular ASIC. For example, an interconnection apparatus may
provide connection of a power supply to the pin, another may
provide for a particular type of signal to or from a pin.
[0019] An advantage of the present invention is that it minimizes
or eliminates hand wired interconnections.
[0020] A further advantage of the present invention is that it
reduces the cost of hand wiring, including related documentation,
wire stripping, wire labeling, installation and testing.
[0021] A still further advantage of the present invention is that
it eliminates or minimizes the need for custom cable harnesses.
[0022] Another advantage of the present invention is that it
reduces the time required to design a new system.
[0023] An advantage of the present invention is that it reduces the
quantity of part numbers in a system.
[0024] A further advantage of the present invention is that it
simplifies maintaining systems in the field because a smaller
number of cables need to be available to replace damaged or
suspected cables.
[0025] A still further advantage of the present invention is that
it aids in making system design changes, because new cable designs
are generally not required.
IN THE DRAWING
[0026] FIG. 1 illustrates a prior art interconnection system using
individual wires;
[0027] FIG. 2 illustrates a prior art interconnection system using
cables;
[0028] FIG. 3 illustrates the prior art use of circuit boards for
interconnecting cable wiring to selected devices;
[0029] FIG. 4a shows a typical prior art custom cable
arrangement;
[0030] FIG. 4b shows another typical prior art custom cable
arrangement;
[0031] FIG. 5 is a block diagram for illustrating the apparatus and
method of the present invention;
[0032] FIG. 6 is a circuit diagram for illustrating further detail
of the module of the connectorized configurable system of the
present invention;
[0033] FIG. 7 is a block diagram illustrating a system for testing
cables using the module of the present invention;
[0034] FIG. 8 is a diagram of a prior art interlock system;
[0035] FIG. 9 is a block diagram of an interlock system using the
configurable connectorized input/output module of the present
invention;
[0036] FIG. 10 illustrates the use of ASIC construction containing
elements of the system of the present invention; and
[0037] FIG. 11 is a more detailed circuit of an example of a pin
driver interface apparatus according to the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0038] Referring now to FIG. 5 of the drawing, a block diagram is
presented for illustration of the method and apparatus of a
preferred embodiment of the present invention. The apparatus of the
present invention includes a configurable input/output system 65
including an input/output module 66 and one or more cables 68. All
of the cables 68 are preferably identical, but the present
invention also includes variations in the cables 68. Each cable 68
includes one or more conductors and connectors 69 and 71. The I/O
module 66 according to the present invention includes a
microprocessor that is programmable for enabling a particular
transmission of a signal between the module 66 and devices 70, and
between the module 66 and a system controller 72. The module 66
also preferably includes one or more device communication
connectors 74, preferably of standard manufacture, for connection
to the device communication cables 68, also preferably of standard
manufacture. A controller communication connector 76 provides
connection to a network (preferably Ethernet) 78 for communication
between the module 66 and the system controller 72. The module 66
is programmed/configured by input from the system controller 72.
Alternatively, the module 66 can be configured to be programmed
through use of a separate computer (not shown).
[0039] For example, the module 66 may be programmed to connect a
power supply voltage from either an external device such as an
external supply 79 or from a supply built into the module 66, to
any one or more of wires associated with corresponding cables 68
for transmission to corresponding interconnected devices 70. As
another example, the controller 72 may program the module 66 to
receive or send a signal from or to any pin of connector 74.
[0040] The module 66 may be programmed to enable transfer of
communication data between any one of the devices 70 and the
controller 72, and this may involve any required analog to digital
(A/D) or digital to analog (D/A) conversion by the module 66.
[0041] FIG. 6 will now be referred to for illustration of further
details of the I/O module 66. The use of the term "standard" as
used in the present specification includes any connector and/or
cable that is not selected or designed for a particular connection.
The term "standard", in other words is used to distinguish the
feature of the present invention that enables the user to direct
input to any one of the conductors of a cable without the need to
design a special connector or cable wire configuration. The term
"standard" as used in this sense may or may not include an
"off-the-shelf" connector or cable that may be designed for any of
various purposes. Nevertheless, it is a preferred embodiment of the
present invention for the method and apparatus to include
"standard" connectors and cables in the conventional sense, making
wiring less costly, and parts more available.
[0042] The I/O module 66 as illustrated in FIG. 6 includes a
directing apparatus 115 including a microprocessor 82 and
alternatively a power supply 84, and one or more interface
apparatus 97. Each interface apparatus 97 connects to one line 94
connected to one pin of a connector 114. The power supply 84 can
alternatively be externally located with interconnection to I/O
module 66 as described in reference to FIG. 5. An input line 86 and
output line 88 are both shown as required for communications input
and output respectively, such as Ethernet, between the module 66
and controller 72 according to a preferred embodiment. Other types
of interconnections are also included in the present invention
according to the type of communications network in use. Bus 86 of
FIG. 6 represents the connection apparatus required for network
communications between a controller such as controller 72 of FIG. 5
and the I/O module 66. Bus 88 of FIG. 6 represents the connection
apparatus required for communication to another I/O module, such as
124 in FIG. 7 between I/O Modules 120 and 122. In general, the
microprocessor 82 is configured/programmed by a controller 72 to
receive instruction from the controller as required to sense a
particular selected one of devices 96, which may be for example a
pressure sensor, temperature sensor, etc., and provide the
corresponding data to the system controller. The microprocessor 82
is also programmed/directed by the controller 72 to cause a
particular signal to be applied to any selected one or more of pins
on connectors 114 and thereby corresponding conductors of one or
more of the cables 94. In addition, the microprocessor is
programmed to respond to direction to send a selected signal type
from a device 96 to the system controller 72.
[0043] FIG. 6 shows an interface apparatus 97A, which may contain
any number of interconnection apparatus such as 98-112, each for
providing a particular selectable interface on a line 94A to a
particular pin of a connector 114A. FIG. 6 shows a second interface
apparatus 97B, which can be identical to apparatus 97A and which
connects to another pin of the connector 114A shown. Similarly an
interface apparatus 97 can be provided for each pin of a connector
such as 114A. FIG. 6 then shows another connector 114N, indicating
that any number of connectors 114 are included in the present
invention, with each connector 114 having any number pins. Each pin
can be interfaced with one dedicated interface apparatus 97. Each
interface apparatus has one or more selectable interconnection
apparatus, such as interconnection apparatus 98-112. The module 66
therefore as shown provides interconnection apparatus 98-112 for
each of a plurality of lines 94 connector pins. Each set of
interconnection apparatus 98-112 is dedicated for making a
connection to one line 94 to one pin of one connector 114. The
present invention therefore includes an interface apparatus
including a set of interconnection apparatus such as 98-112 and
corresponding required programmed logic in the microprocessor 82
for each line 94 leading to each one of the connector pins of
connectors 114, the pins for example as indicated by the circles on
connector 114, for making connection through a cable 68 to any
corresponding device 70.
[0044] As an example of operation of the system 65, the
microprocessor may be programmed to recognize particular input
data, included for example in an Ethernet packet on line 86
containing instruction to transmit the data as an analog signal on
a particular on line 94 to a particular device 70. The programming
in this case would instruct the microprocessor to direct/convert
the data through apparatus 98 having a digital to analog converter
116. Facility for making this connection is symbolized by relay
"R1" which would be activated to make the required connection from
the device 116 to the device 70. As another example, if line 94
were to carry 15 volts to the device 70, the microprocessor would
be Programmed to respond to a signal from the controller to
activate relay R6. In this manner, the system 65 allows
communication of a selected variety through any line such as 94,
and application of any one of a variety of signals to be sent to
any selected line such as 94 and thence to a corresponding device
70. The cable connecting to the lines such as line 94 can therefor
be any cable capable of transmission of the required signals, which
as explained above is preferably a conventionally standard
cable.
[0045] The circuit switching apparatus (R1-R8) are shown
diagrammatically as electromechanical relays. In one embodiment,
this switching apparatus is realized in a semiconductor circuit. A
semiconductor circuit can be realized far less expensively and can
act faster than an electromechanical relay circuit. An
electromechanical relay is used in order to show the essence of the
invention.
[0046] As shown in FIG. 6, any one of the eight signal path
interconnection apparatus indicated as 98-112 can be interconnected
to line 94. FIG. 6 shows, for example, apparatus for supplying four
different power supply signals for operational power to a
particular pin including 24V DC, ground, 15V DC and -15V DC. The
present invention also includes any quantity or value of signals.
Interconnection apparatus 102 provides for a digital signal to the
pin connection to line 94. Interconnection apparatus 108 provides a
power supply return/ground. Interconnection apparatus 98 and 100
provide digital-to-analog conversion, and analog-to-digital
conversion respectively. The directing apparatus microprocessor 82
is programmable to direct the module 66 to output a first signal to
the controller wherein the first signal conveys data content of a
signal input from a device 70 to the module 66 to a selected one of
the pins 117 of the connector 114. As described above, the module
66 is configured with a set of interconnection apparatus such as
98-112 for each line 94 (FIG. 6) in each cable 68 (FIG. 5).
[0047] The lines and interconnections can carry any signal type.
For example, signals can contain frequency information such as that
found in feedback from servo motors. Or these signals can represent
serial communication carriers handling, for example, RS-232 data or
fieldbus data such as Device Net, Profibus or Ethernet.
[0048] FIG. 6 also illustrates the facility for connection of four
non-power signals by interconnection apparatus 98-104.
Interconnection apparatus 98 and 100 include A/D and D/A
converters, as well as switching apparatus (RI and R2), for
situations where such conversion is necessary to accommodate
different transmission and reception capabilities/requirements of
the controller 72 and a device 70. Interconnection apparatus 102
and 104 provide for passage of digital signals in either direction.
In further explanation, the controller can direct the module 66 to
send a digital signal, which when received by the module 66, can be
sent to a buffer 118, from which the microprocessor 82 in response
to direction from the controller can send the signal to any one of
the contacts on connector 114 by activating the required relay,
such as interconnection apparatus 104 to connector 114, to send the
required signal to the desired contact of the desired connector.
Again, the routing of the signals is symbolically illustrated as
accomplished by closing the associated relay (R1-R8). In the case
of the aforementioned digital output signal, as shown in FIG. 6,
relay R4 would be closed, but relays R1-R3 and R5-R8 would be
opened, thus routing the requested digital output to line 94 and
the corresponding pin of the standard I/O connector 114. Similarly,
the module 66 can receive a digital signal from a device 72, such
as device 96, and in response to direction from the controller can
send a copy to the controller 72. In this case, relay R3 would be
closed, while relays R1-R2 and R4-R8 would be opened, thus routing
the digital signal from the given pin of the standard I/O connector
114 through interconnection apparatus 102. Interconnection
apparatus 98 and 100 accommodate analog to digital conversion as
required. Finally, the configurable I/O system 65 can be isolated
from a signal such that the signal appears to be disconnected. This
disconnection is achieved by opening all relays, R1-R8.
[0049] Referring again to FIG. 5, a preferred method of the present
invention includes the use of the system 65 in a control system
wherein a controller 72 receives data from or sends data to one or
more devices 70 through an I/O module 66 that is programmed to
receive signals from and place signals on any selected conductor of
a selected cable to a device 70. In a preferred embodiment, the
device 72 is a system controller in communication with the I/O
module 66 through an Ethernet system 78. Alternatively, the device
72 can be of other configuration, such as a general purpose
computer, and the communications line 78 can be of any type, such
as a standard computer cable, etc.
[0050] A further method of the present invention includes the use
of the module 66 for testing cables. FIG. 7 shows a first I/O
module 120, connected to a second I/O module 122 with a cable 124
to be tested. According to a preferred embodiment, a system
controller 126 is programmed to direct module 120 to place a
particular signal on a selected one of wires 128 in cable 124. The
signal can be for example, a DC supply voltage or other signal type
as required for testing the cable 124. The controller directs the
second module 122 to scan the pins 130 of the second module 122.
The results of the scanning are sent to the controller 126, whereby
the controller can know if the correct signal is on the correct pin
to determine the condition of the cable. In addition to determining
the quality of transmission through a single selected cable
conductor, the controller can scan and detect a signal on any pin
130 of the connector of module 122, and therefore can determine if
any of the conductors 128 are shorted to each other, and can
determine the level of cross talk between the conductors 128. FIG.
7 shows dashed lines 132 and 134 representing communication lines
between the system controller 126 and the Modules 120 and 122.
[0051] A still further embodiment of the present invention includes
a method wherein a module configured to include the features of
module 66 is combined with an interlock for providing a safety
feature in a system. FIG. 8 illustrates a prior art interlock
system for protecting use of a gas valve 134. Three relays 136, 138
and 140 must conduct current from a 24VDC supply 142 in order for
the gas valve 134 to receive operating power. The electrical
windings for operating the relays 136, 138 and 140 are symbolized
by the circles 142, 144 and 146. The power to each winding is
controlled by the sensor units 148, 150 and 152. If any one of the
three sensor units is activated and therefore disconnects power to
the corresponding winding, the associated relay disconnects/open
circuits and shuts off power to the gas valve. The interlock
circuit of FIG. 8 is often built into a custom circuit board
requiring custom wiring.
[0052] An embodiment of a method of the present invention is
illustrated in FIG. 9 wherein configurable connectorized I/O
Modules 166, 168 and 170, such as module 66, are used to minimize
or eliminate custom wiring in an interlock system. The Modules 166,
168 and 170 may be similar or identical to the module 66 of FIGS. 5
and 6 with connections to the interlock Modules 180, 182 and 184.
The interconnections indicated in FIG. 9 can all or in part be
accommodated with standard connectors and cabling, with the
specific direction/routing of signals accomplished by programming
the configurable, connectorized I/O modules.
[0053] The exemplified system 154 of FIG. 9 includes a system
controller 156 for controlling an operation including a device 158
such as a mass flow control, etc. The system 154 includes an
interlock system that allows operation of the device 158 only if
the state of all three safety sensors 160, 162 and 164 indicate
that operation conditions are appropriate. The sensors can be of
any type for the purpose. The three examples are a proximity switch
160, a safety interlock 162 and a limit switch 164.
[0054] The system controller 156 is connected to each of the three
configurable, connectorized I/O Modules 166, 168 and 170 which
provide the programmable flexibility as described above, to allow
standard cables and connectors to be used throughout the system to
make the various connections indicated. I/o Modules 166, 168 and
170 are shown overlapping the interlock Modules 180, 182 and 184
indicating that the interlock Modules 180, 182 and 184 plug into
the I/O Modules 166, 168 and 170. In the preferred embodiment, the
interlock Modules 180, 182 and 184 plug into connector 74 of an I/O
module such as Module 66 of FIG. 5 in place of a cable 68. The
interlock Modules 180, 182 and 184 each contain a device connector
74 into which a cable 68 plugs for interconnecting the devices
158-164. The interlock Modules 180, 182 and 184 therefore reside
between the I/O Modules 166, 168 and 170 and the devices 158-164 to
which they attach, including as shown by example in FIG. 9 a
proximity switch 160, limit switch 164, and safety interlock 162,
and device 158.
[0055] The system controller 156 communicates with I/O Modules 166,
168 and 170, and with the interlock processor 172 by way of a
network, such as Ethernet as indicated by lines 174. Apparatus for
accomplishing Ethernet communication will be understood to those
skilled in the art, and this need not be illustrated in order to
reproduce the invention. A power supply 176 is shown with the
connections symbolized by lines 178. An interlock module (180, 182,
184) is attached to each of the 1/0 modules (166, 168, 170). Each
interlock module (180- 184) is attached to the interlock processor
172 through cables/buses as indicated by lines 186, 188 and
190.
[0056] The interlock system of FIG. 9 will not be explained in
further detail. In general, the system 154 includes interlock
modules (180, 182, 184) connected to an interlock processor 172 via
bus lines (186, 188, 190). The Interlock Modules have two
functions: (1) The first function, of the Interlock Modules 180 and
182, is to transmit the state of certain inputs, for example 192,
194 and 195 from sensors 160, 162 and 164, such inputs being a
subset of all inputs and being called Interlock Inputs, to the
Interlock Processor 172 via the Interlock Buses 186 and 188. Any
input (192, 194, 195) connected to any interlock module (180-184)
can be wired within the interlock module such that the input drives
a relay coil, as shown in FIG. 8, with relay coils labeled (142,
144, 146). When these relay coils are actuated, the associated
relay contacts close. These relay coils each activate a contact
resulting in a signal being sensed by or sent to the Interlock
processor 172 via the interlock buses 186 and 188 to the Interlock
Processor 172. The function of the Interlock Processor will be
described shortly. (2) The second function, of the Interlock Module
184, is to receive one or more interlock signals from the Interlock
Processor 172 via the Interlock bus 190. The Interlock Processor is
wired such that the interlock signal or signals that the processor
sends on the bus 190 drives a coil of a relay located in the
Interlock module 184 whose contacts are in series with an output of
the I/O module 170. This output 197 is therefore interlocked. That
is, the I/O module 170 can attempt to turn on an output connected
to the device 158, but that output 197 will be prevented from
progressing outside the Interlock Module 184 (that is, interlocked)
unless the Interlock Processor 172 drives a signal on the Interlock
bus 190 which closes a relay in series with the output 197. The
Interlock Processor 172 is responsive to inputs from the Interlock
Modules 180 and 182 by performing Boolean logic upon the inputs to
generate one or more interlock outputs on bus 190 that are routed
to the Interlock Module 184 and thereby interlock output 197 from
the I/O Module 170. The Interlock Processor 172 preferably does all
of its processing using relays. Relays are common in safety
circuits since they are simple and reliable. Silicon switches and
microprocessors have the reputation for being less reliable and
prone to various hardware or software glitches. Nonetheless,
nothing in this application precludes the use of silicon
processors, switches or logic. The cables 186, 188 and 190 are
shown making direct connection between each interlock module and
the interlock processor.
[0057] In operation, the proximity switch 160 provides an interlock
input 192 that is connected directly to the first interlock module
180. The safety interlock 162 provides a similar input 194. These
two interlock inputs 192 and 194 are sensed by the system
controller 156 by way of connection between the interlock module
180 and the I/O module 166, and input monitoring communications
between the I/O module 166 and system controller 156 by way of
network 174. The interlock module 180 contains one relay for each
interlock input 192 and 194. These relays (not shown) are for
driving a signal via the Interlock Bus 186 to the Interlock
Processor 172. The Interlock Processor 172 contains one relay for
each interlock input 192 and 194. The relays are arranged within
the Interlock Processor 172 to perform a Boolean operation on the
Interlocks 160, 162, 164 and generate an interlock output that is
routed via the Interlock Bus 190 to the Interlock Module 184.
Inside the Interlock Module 184 is one relay (not shown) for each
output such as output 197 to be interlocked. In other words,
although only one output 197 to one device 158 is shown in FIG. 9,
the concept of the present invention applies to any number of
inputs, outputs and devices. When the Interlock Processor 172
determines that the Interlock inputs 160, 162, 164 are in their
correct states for proper system operation, the Interlock Processor
172 drives a signal via the Interlock bus 190 and causes the relay
in the Interlock Module 184 to close, thus allowing an output on
line 197 and therefore the device 158 to be enabled or turned
on.
[0058] Referring now to FIG. 10 of the drawing, another embodiment
of the present invention is illustrated wherein the interface
apparatus including interconnection apparatus such as 98-112
illustrated in FIG. 6 is configured as an application specific
integrated circuit (ASIC) 198. The ASIC 198 is repeated within the
I/O module 200 for each pin of each connector 202. For example, a
series of ASICs 198 for the pins on one connector 202 are indicated
by those enclosed by dashed line 204. Thus, if the connector 202
has 25 pins, then 25 ASICs 198 would be employed for that one
connector. The module 200 can contain any number of ASICs 198, just
as any module may contain any number of connectors 202. Another
embodiment may employ a different ASIC architecture in which
multiple pins are handled in each ASIC or multiple ASICs are used
to handle one or more pins. The result of using an ASIC is a
dramatic reduction in the size and cost of building a module 200 by
virtue of the miniaturization afforded by modern semiconductor
processes. Again, the circuit 200 of FIG. 10 is functionally
similar or the same as that circuit module 66 described in
reference to FIG. 6. The difference is that the circuitry providing
the function of interconnection apparatus 98-112 or any combination
of the elements 98-112 or other elements for
interfacing/communication with a pin, are incorporated in an ASIC
198 in the circuit 200 of FIG. 10.
[0059] FIG. 11 depicts a block diagram of a pin driver ASIC 198.
When connected to the microprocessor 82 by a serial communication
bus 206 such as an SPI interface, the microprocessor 82 of FIG. 10
can command the ASIC to perform the functions of the circuits of
FIG. 6 shown as 98-112. Although the circuitry. of FIG. 11 appears
different from the interconnection apparatus 98-112 of FIG. 6, the
circuit 198 is capable of performing the same or similar required
functions. Whereas FIG. 6 is a somewhat idealized diagram intended
to convey the essence of the invention, FIG. 11 contains more of
the circuit elements that one would place inside an ASIC.
Nonetheless, FIG. 11 implements all the circuit elements of FIG. 6.
For example, FIG. 6. uses switch 98 to connect a digital-to-analog
converter (D/A or DAC) to the output line 94A. In FIG. 11, the
digital-to-analog converter 226 is connected to the output pin 208
via the switch 220. The present invention also includes other
circuit arrangements for an ASIC 198 for the same or similar
purpose. Those skilled in the art will know how to design various
such circuitry, and these are to be included in the present
invention.
[0060] Exemplary features of the circuit of FIG. 11 will now be
briefly described. Power may be applied to pin 208 by closing high
current switch 222b and setting the supply selector 227 to any of
the available power supply voltages such as 24-volts, 12-volts,
5-volts, ground or negative 12-volts.
[0061] The circuit can measure the voltage on pin 208 by closing
the low current switch 222 and reading the voltage converted by the
analog-to-digital converter 216.
[0062] The circuit can direct connect a thermocouple temperature
sensor connected at point/pin 208, wherein the sensor produces a
very low voltage signal. A cross-point switch 210 allows a
precision differential amplifier 212 to connect to both leads of
the thermocouple, one lead of the thermocouple being connected to
the node/pin 208 connected to a pin of a connector 202 (FIG. 10),
and the second lead of the thermocouple connected to another pin of
the connector 202, which is connected to a 4-way cross-point I/O
214 connector. The cross-point switch 210 therefore allows two
adjacent pins of a connector 202 to be connected to the same
analog-to-digital converter 216 via a differential amplifier
212.
[0063] Circuit 198 has the ability to measure the amount of current
flowing in or out of the node 208 labeled pin of FIG. 11. The pin
driver circuit 198 in this case uses its A/D converter 216 to
measure current flowing into or out of the pin node 208, thereby
enabling the detection of excessive current, or detecting whether a
device connected to the pin node 208 is functioning or wired
correctly.
[0064] ASIC 198 also has the ability to monitor the current flow
into and out of the pin node 208 to unilaterally disconnect the
circuit 198, thereby protecting the ASIC 198 from damage from short
circuits or other potentially damaging conditions. The ASIC 198
employs a so-called abuse detect circuit 218 to monitor rapid
changes in current that could potentially damage the ASIC 198. Low
current switches 220, 221 and 222 and high current switch 222b
respond to the abuse detect circuit 218 to disconnect the pin
208.
[0065] The ASIC 198 abuse detect circuit 218 has the ability to
establish a current limit for the pin 208, the current limit being
programmatically set by the microprocessor 82. This is indicated by
selections 224.
[0066] The ASIC 198 can measure the voltage at the pin node 208 in
order to allow the microprocessor 82 to determine the state of a
digital input connected to the pin node. The threshold of a digital
input can thereby be programmed rather than being fixed in
hardware. The threshold of the digital input is set by the
microprocessor 82 using the digital-to-analog converter 226. The
output of the digital-to-analog converter 226 is applied to one
side of a latching comparator 225. The other input to the latching
comparator 225 is routed from the pin 208 and represents the
digital input. Therefore, when the voltage of the digital input on
the pin 208 crosses the threshold set by the digital-to-analog
converter, the microprocessor 82 is able to determine the change of
the input and thus deduce that the digital input has changed
state.
[0067] The ASIC 198 can receive or produce frequency signals. If a
serial communication device, for example a printer, is connected to
pin 208, then said frequency signals can be routed through the low
current switch 221 and thence to a universal asynchronous receiver
transmitter (UART) or similar circuit element (not shown) that can
interpret the frequency information. All of the ASICs 198 in a
module 66 can route the frequency information to one of four wires
that make up the frequency bus 230. By employing said frequency bus
230, it is possible for the module 66 to receive and transmit
frequency signals configured as either single-ended or
differential. Such serial electrical standards as RS-422 provide
for differential serial information.
[0068] The ASIC can produce a current source at the pin node, the
current source being a standard method of connecting various
industrial control devices. The ASIC can produce signals varying
over the standard 4-20 mA and 0-20 mA range. This current source
means is accomplished by the microprocessor 82 as it causes the
digital-to-analog converter 226 to produce a voltage which is
routed to the Selectable Gain Voltage Buffer or Current Driver 231
and then through the selectable source resistor 227, said
selectable source resistor 227 being set to the appropriate
resistance by the microprocessor 82 to achieve the desired output
current. The current is regulated by the Selectable Gain Voltage
Buffer or Current Driver 231 using feedback through the analog
switch 229 using path A.
[0069] The ASIC can measure a current signal presented at the pin
node, the current signal being produced by various industrial
control devices. The ASIC can measure signals varying over the
standard 4-20 mA and 0-20 mA range. This current measurement means
is accomplished by the microprocessor 82 as it causes the
selectable gain voltage buffer 231 to produce a convenient voltage
such as zero volts at its output terminal. At the same time, the
microprocessor 82 causes the selectable source resistor 228 to
present a resistance to the path of current from the industrial
control device and its current output. Said current enters the ASIC
198 via the pin 208. The imposed voltage on one side of a known
resistance will cause the unknown current from the external device
to produce a voltage on the pin 208 which is then measured via the
analog-to-digital converter 216 through the low current switch 222.
The microprocessor 82 uses Ohm's Law to solve for the unknown
current being generated by the industrial control device.
[0070] Other enhancements of the present invention include the
ability of the module 200 to perform independent control of devices
connected to the module 200. If, for example, a thermocouple or
other temperature sensor is connected to the module 200 along with
a heater, then the microprocessor 82 can read the temperature
sensor, and activate the heater in such a manner that a desired
temperature is achieved. Said heater usually employs an amplifier
(for example a relay) which converts the low-level output of the
module 200 into a high-power output capable of driving a heater.
The module 200 can thereby perform closed loop control. In such as
case, said thermocouple would be connected to two adjacent pins 208
configured as inputs, while said heater would be connected to two
pins 208, said heater pins being configured as outputs. In
operation, the microprocessor 82 would measure the voltage of the
temperature sensor as described above. The microprocessor 82 would
apply the desired temperature using known control algorithms to the
measured temperature and develop an actuation signal also using the
accepted methods. The microprocessor would then actuate the heater
either with a continuously variable analog signal or via a pulse
width modulated (PWM) on/off signal. Thus, independent control of
devices connected to the module 200 is achieved.
[0071] The ASIC 198 includes functions as described above in
reference to the interface apparatus 97. For example, an ASIC 198
has an interconnection apparatus having a digital-to-analog
converter, 226, and wherein the directing apparatus is programmable
to direct the reception of a digital signal from the microprocessor
82 and cause the signal to be converted by the digital-to-analog
converter 226 to an analog signal, and to place a copy of the
analog signal on the pin 208.
[0072] The ASIC 198 can also include an interconnection apparatus
including an analog-to-digital converter 216, and wherein the
directing apparatus is programmable to detect an analog signal on
any selected contact of the first connector apparatus and cause the
analog-to-digital converter 216 to convert the signal to a digital
signal and output a copy of the digital signal to the
microprocessor 82.
[0073] The ASIC 198 can also include directing apparatus, called a
supply selector 227, and then routed through the high current
switch 222b to the pin 208. Said directing apparatus is
programmable to cause a power supply voltage to be connected to a
first selected connector pin node of the first connector apparatus,
and to cause a power supply return to be connected to a second
selected pin of the first connector apparatus.
[0074] While a particular embodiment of the present invention has
been shown and described, it will be obvious to those skilled in
the art that changes and modifications may be made without
departing from the spirit of the present invention, and therefore
the appended claims are to include these changes and alterations as
follow within the true spirit and scope of the present
invention.
* * * * *