U.S. patent application number 12/017374 was filed with the patent office on 2011-12-29 for method and device for communicating electrical positioning information of a final control element.
Invention is credited to Harald Kah.
Application Number | 20110320162 12/017374 |
Document ID | / |
Family ID | 39587119 |
Filed Date | 2011-12-29 |
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United States Patent
Application |
20110320162 |
Kind Code |
A1 |
Kah; Harald |
December 29, 2011 |
METHOD AND DEVICE FOR COMMUNICATING ELECTRICAL POSITIONING
INFORMATION OF A FINAL CONTROL ELEMENT
Abstract
In a method for communicating electrical positioning information
of an actuator-positioned final control element such as a valve
element, the positioning information resulting from continually
sensing the position of the final control element, a binary signal
is formed or received signalling a condition 0 (zero) when the
final control element has attained a predefined position and a
condition 1 (one) when the final control element has not attained
the predefined position or the predefined position range. For
forming a positioning signal, the corresponding signal condition of
the binary signal and the associated continually sensed positioning
information are combined such that the corresponding signal
condition of the binary signal or the positioning information or
both can be optionally invoked from the positioning signal.
Inventors: |
Kah; Harald; (Brechen,
DE) |
Family ID: |
39587119 |
Appl. No.: |
12/017374 |
Filed: |
January 22, 2008 |
Current U.S.
Class: |
702/150 |
Current CPC
Class: |
Y10T 137/0318 20150401;
G08C 21/00 20130101; Y10T 137/8242 20150401 |
Class at
Publication: |
702/150 |
International
Class: |
G06F 15/00 20060101
G06F015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 30, 2007 |
DE |
10 2007 004 595.8 |
Claims
1. A method for communicating electrical positioning information of
an actuator-positioned final control element, said positioning
information resulting from continually sensing a position of the
final control element, comprising the steps of: forming or
receiving a binary signal having a signal condition 0 when the
final control element has attained a predefined position or
position range, and a signal condition 1 when the final control
element has not attained the predefined position or the position
range; and for forming a positioning signal combining the signal
conditions of the binary signal and the continually sensed
positioning information such that the signal conditions of the
binary signal, the positioning information, or both can be
optionally invoked from said positioning signal.
2. A method of claim 1 wherein to form the positioning signal the
continually sensed positioning information is modulated onto the
binary signal.
3. A method of claim 1 wherein the continually sensed positioning
information is digitized before being combined with the binary
signal.
4. A method of claim 1 wherein the continually sensed positioning
information is frequency modulated for combination with the binary
signal.
5. A method of claim 1 wherein the positioning signal is
communicated via a single output terminal.
6. A method of claim 1 wherein a method parameter for setting or
configuring the method is received for generating the binary signal
from the positioning information via a signal line used to
communicate the positioning signal.
7. A method of claim 1 wherein in a certain operating mode of the
actuator the positioning signal is reduced to the signal conditions
of the binary signal and the positioning signal reduced to the
signal conditions is output.
8. A method of claim 1 wherein in a certain operating mode the
positioning signal is, where necessary, reduced to the continually
sensed positioning information and the reduced positioning signal
is sent.
9. A method of claim 1 wherein the binary signal indicates MAX or
MIN violation of an adjustable position alarm.
10. A method of claim 1 wherein the position is cached for a
predetermined period of time of actuator operation.
11. A method of claim 1 wherein in addition to at least one of the
binary signal and the associated continually sensed positioning
information additional information is attached to the positioning
signal assigned to the continually sensed positioning
information.
12. A method of claim 1 wherein the predefined position comprises
an emergency position.
13. A method of claim 1 wherein the final control element comprises
a valve element.
14. A system for transmitting electrical positioning information of
an actuator-positioned final control element, comprising: a
communication device having an input for receiving continually
sensed positioning information from a sensor and an output for
forwarding a positioning signal; said communication device
generating or receiving by way of the positioning information a
binary signal signalling a condition 0 when the final control
element has attained a predefined position or a predefined position
range, and signalling a condition 1 when the final control element
has not attained the predefined position or the predefined position
range; and said communication device combining the signal
conditions of the binary signal and the continually sensed
positioning information for forming said positioning signal such
that the signal conditions of the binary signal, the positioning
information, or both can be optionally invoked from said
positioning signal.
15. A system of claim 14 wherein the output is formed by a sole
terminal for communicating the positioning signal.
16. A system of claim 14 wherein the communication device is
designed to receive a setting for generating the binary signal via
a signal line connected to the output.
17. A system of claim 14 wherein the communication device has an
electronic module for processing the positioning information for
generating the binary signal.
18. A system of claim 14 wherein the communication device has an
electronic module which processes the signal conditions and the
positioning information for forming the positioning signal.
19. A system of claim 18 wherein the electronic module has a
modulation component which modulates the positioning information on
the binary signal.
20. A system of claim 18 wherein the electronic module comprises a
microcomputer.
21. A system of claim 14 wherein the communication device comprises
an analog to digital converter for digitizing the positioning
information.
22. A system of claim 14 wherein the communication device comprises
a filter for reducing the positioning signal to only the binary
signal or the positioning information.
23. A system of claim 14 wherein the output is connected to a
two-wire line for forwarding the positioning signal.
24. A system of claim 14 wherein the sensor comprises a Hall sensor
or a magneto-resistive sensor for sensing the position of the final
control element.
25. A system of claim 14 wherein the control element comprises a
valve element.
26. A system of claim 14 wherein the predefined position comprises
an emergency position.
27. A system for transmitting electrical positioning information of
an actuator-positioned final control element comprising a valve
element, comprising: a communication device having an input for
receiving continually sensed positioning information from a sensor
positioned to sense a position of said valve element and an output
for forwarding a positioning signal; said communication device
generating or receiving by way of the positioning information a
binary signal signalling a first condition when the valve element
has attained a predetermined position or a predefined position
range, and signalling a second condition when the valve element has
not attained the predefined position or the predefined position
range; and said communication device combining the signal
conditions of the binary signal and the continually sensed
positioning information for forming said positioning signal such
that the signal conditions of the binary signal, the positioning
information, or both can be optionally invoked from said
positioning signal.
28. A method for communicating electrical positioning information
of an actuator-positioned final control element, said positioning
information resulting from continually sensing a position of the
final control element, comprising the steps of: forming or
receiving a binary signal having a first signal condition when the
final control element has attained a predefined position or
position range, and a second signal condition when the final
control element has not attained the predefined position or the
position range; and for forming a positioning signal combining the
signal conditions of the binary signal and the continually sensed
positioning information such that the signal conditions of the
binary signal, the positioning information, or both can be
optionally invoked from said positioning signal.
Description
BACKGROUND
[0001] The preferred embodiment relates to a method and device for
communicating electrical positioning information of an
actuator-positioned final control element such as a valve element.
The positioning information is usually continually sensed with the
aid of an analog sensor for implementing display and/or closed loop
control of the position.
[0002] It is particularly in the field of process engineering and
nuclear technology that final control valves are used in flow lines
which, due to stringent safety requirements, are actuated by
pneumatic actuators. These so-called field devices are usually also
designed to automatically position in an emergency, for example, to
close the valve element.
[0003] "Seeing" that this position really has been attained in an
emergency is vital to safe operation. Known are alarm units such as
the so-called namur contact as per the EN 60947-5-6 directive which
is usually configured as an inductive proximity switch that
transmits a binary signal to a display, by means of which the
system can "see" whether the valve element has assumed the alarm
position, i.e. the desired emergency position, or not.
[0004] Continually sensing the position for example by means of a
Hall sensor has the known advantage over a simple alarm that closed
loop control of positioning in accordance with the desired flow in
the conduits and watchdogging the precise travel of the valve
element in an emergency are possible. On the other hand, however,
the simple alarm approach has the advantage of a low electrical
energy requirement and safe functioning which is most welcome
especially in an explosive hazard environment. To satisfy all
safety aspects involved it would be a good thing to make available
both a continual sensing of the position and an alarm for the field
device concerned. Unfortunately this involves an expensive and
complicated design.
SUMMARY
[0005] An object is to overcome the drawbacks of prior art in
designing particularly a method and device for transmitting
electrical positioning information of an actuator-positioned final
control element such as a valve element at minimum expense and
complications in keeping with the advantages of continual position
sensing while satisfying the requirement for a low energy
consumption.
[0006] In a method for communicating electrical positioning
information of an actuator-positioned final control element, the
positioning information resulting from continually sensing a
position of the final control element, a binary signal is formed or
received having the signal condition 0 when the final control
element has attained a predefined position or position range, and a
signal condition 1 when the final control element has not attained
a predetermined position or the position range. For forming a
positioning signal, the signal condition of the binary signal and
the continuously sensed positioning information are combined such
that the signal conditions of the binary signal, the positioning
information, or both can be optionally invoked from the positioning
signal.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] FIG. 1 is a block diagram of the structure of a field device
actuated by a pneumatic actuator featuring a device in accordance
with the preferred embodiment; and
[0008] FIG. 2 is a graph plotting an analog positioning information
in Ma as a function of time.
DESCRIPTION OF THE PREFERRED EMBODIMENT
[0009] For the purposes of promoting an understanding of the
principles of the invention, reference will now be made to the
preferred embodiment/best mode illustrated in the drawings and
specific language will be used to describe the same. It will
nevertheless be understood that no limitation of the scope of the
invention is thereby intended, and such alterations and further
modifications in the illustrated device and such further
applications of the principles of the invention as illustrated as
would normally occur to one skilled in the art to which the
invention relates are included.
[0010] In accordance with the preferred embodiment, continually
sensed positioning information is now provided both for the method
and for the device, on the basis of which the binary signal is to
be formed or received signalling the condition 0 when the final
control element has attained a predefined position, such as an
emergency position or a predefined position range, and signalling
the condition 1 when the final control element has not attained the
predefined position or the predefined position range. In accordance
with the preferred embodiment the alarm function, particularly
emergency watchdogging, is now achieved with the aid of continually
sensed positioning information without the need of such hardware as
contact makers or inductive proximity switches for signalling the
alarm. In accordance with the preferred embodiment the continually
sensed positioning information and the binary signal developed
therefrom are now combined such that a positioning signal is formed
from which optionally the corresponding signal condition of the
binary signal or the positioning information or both can be
invoked. In other words, in accordance with the preferred
embodiment just one positioning signal is now produced which
provides information both as to the continually sensed position and
as to the alarm, i.e. depending on the energy available the
corresponding information can be invoked as a function of the
operating situation.
[0011] The binary signal having a condition 0 (zero) shall be
considered as a "living" zero point, i.e. it represents in its
condition, as in the condition 1 (one), as a certain physical
value, for example an electrical current of below 1.5 mA and above
1.8 mA, respectively, or an electrical voltage. The binary signal
can be produced by a so-called Namur-contact which is a limit
switch.
[0012] Additionally, it shall be clear that instead of the
positioning information other types of information can be combined
with the binary signal, such as diagnostic data, device
characterizing data, calibration data, etc.
[0013] Further, it shall be clear that the positioning signal
generated by combining the binary signal to which the analog signal
is modulated, can be transferred bidirectional particularly between
a limit switch generating the binary signal, and a control
system.
[0014] It will be appreciated that the positioning signal produced
by this combination can now transmit not just binary information
and continually sensed positioning information simultaneously via a
single signal line, but also additional information data, for
example, in the form of a data packet relating to the profile, such
as the distance/time profile of the positioning motion of the
actuator in the position as currently sensed. In addition, the
positioning signal may include diagnostic information. Should, for
example, attaining the current position as indicated by the
distance/time profile be slower than wanted, the positioning signal
can include "too slow" diagnostic information in combination.
[0015] In a preferred aspect, to form the positioning signal the
continually sensed positioning information is modulated on the
binary signal, i.e. use being made of the binary signal as an
electrical signal carrier.
[0016] Preferably the continually sensed positioning information
when comprising analog information is digitized before being
combined with the binary signal.
[0017] To achieve an optimally simple combination of each signal
condition and the corresponding positioning information the
continually sensed positioning information is frequency modulated
for combination with the binary signal in making use of a data
communication protocol such as the HART protocol.
[0018] In another preferred aspect communication may be made also
opposite to the direction in which the positioning signal is
transmitted, i.e. in the direction of the device in accordance with
the preferred embodiment in which the binary signal is combined
with the continually sensed positioning information signal. For
example, a setpoint value such as a position alarm for generating
the binary signal may be set by the communication in the opposite
direction when desired, in that the desired setpoint value is
communicated to the device in accordance with the preferred
embodiment via the signal communication line for the combined
positioning signal.
[0019] To save even more energy and to permit reacting to
corresponding operating situations for providing high or low levels
of energy, the method in accordance with the preferred embodiment
can be designed to reduce the positioning signal to the
corresponding signal condition of the binary signal so that only
the positioning signal reduced to the corresponding signal
condition is output, as may be particularly of advantage when the
energy of the operating condition of the actuator is low or
insufficient for the continually sensed positioning information
prompting a relatively high energy requirement.
[0020] In an operating condition during which a change,
particularly suddenly or closed loop control of the positioning
motion of the final control element is desired, the positioning
signal can be likewise reduced, namely exclusively to the
continually sensed positioning information without the
corresponding signal condition of the binary signal, the
corresponding reduced signal then being forwarded.
[0021] In another preferred aspect in particular a non-volatile
memory for the positioning signal is provided so that it can only
be cached for a certain period of time, on timeout of which the
non-volatile memory can be overwritten with the new positioning
signals in thus ensuring that in an emergency situation in which
the corresponding final control element is deactivated it is always
the last positioning signal data that is cached non-volatile.
[0022] In still another preferred aspect of the device in
accordance with the preferred embodiment an electronic component,
particularly a microchip is provided which generates the binary
signal on the basis of the continually sensed positioning
information. In addition, an electronic module, particularly a
microchip may be provided which processes the corresponding signal
condition and the positioning information associated therewith to
form the positioning signal. The electronic module may comprise a
microcomputer which modulizes the positioning information on the
binary signal, particularly in making use of a HART protocol.
[0023] In yet another preferred aspect of the preferred embodiment
the electronic component and the electronic module are achieved as
a module, such as a microcomputer, the microcomputer thus being
able to undertake both modulation and generation of the binary
signal.
[0024] Preferably an analog to digital converter for digitizing the
positioning information is inserted immediately downstream of the
input of the device and preferably upstream of the electronic
module and electronic component.
[0025] In addition, the device in accordance with the preferred
embodiment may comprise a filter for reducing the positioning
signal to just the binary signal or just to the positioning
information.
[0026] Preferably the output of the device is connected to a
two-wire line for forwarding the positioning signal.
[0027] In addition, the preferred embodiment relates to a sensor,
particularly a Hall sensor or a magneto-resistive sensor
particularly intended for analog detection of the position of a
final control element, such as a valve element, positioned by an
actuator, the sensor being provided with a device in accordance
with the preferred embodiment.
[0028] Referring now to FIG. 1 there is illustrated a field device
in accordance with the preferred embodiment, such as a final
control valve assembly identified in general by the reference
numeral 1. The field device 1 comprises a pneumatic actuator 3
actuating a final control valve 5 via a valve stem 7. A
magneto-resistive sensor 9 disposed adjoining the positioning stem
7 senses the position of the stem 7 in detecting the position of a
valve element (not shown) of the final control valve 5.
[0029] The sensor 9 is connected to a positioner 11 which from a
comparison of the setpoint value and actual value outputs a control
signal to the pneumatic actuator 3 via a control line 13 and
features a position display (not shown).
[0030] A device in accordance with the preferred embodiment for
communicating a positioning signal S is identified in general in
FIG. 1 by the reference numeral 15.
[0031] The communicating device 15 comprises an input 17 connecting
an analog to digital converter 19. The analog to digital converter
19 digitizes the analog positioning information a sensed by the
sensor 9 and passes it on to a microcomputer 21. The microcomputer
21 generates from the positioning information A a binary signal
designed like a normal Namur contact and comprising a signalled
condition 1 when the final control valve 5 is in a closed position
(not shown). If the final control valve 5 permits a flow the binary
signal comprises a signalled condition 0
[0032] As an alternative, the two functions combined in the
microcomputer 21--generating the binary signal and modulating the
continually sensed positioning information on the binary
signal--can be split into two components. For example, the analog
to digital converter 19 could be directly followed by a binary
signal generator (not shown) which with the aid of a comparator
(likewise not shown) compares the continually sensed positioning
information to a positioning alarm and outputs the corresponding
binary signal (0/1) to the microcomputer 21 by which then the
analog positioning information is modulated on the generated binary
signal.
[0033] The microcomputer 21 comprises a modulation component (not
shown) which modulates the continually sensed, digitized
positioning information in accordance with the HART protocol such
that the digital positioning information is superimposed in
accordance with its frequency on the associated binary signal. The
positioning signal S output at the output 23 of the communication
device 15 to a two-wire line 25 contains both each signal condition
of the binary signal as well as the continually sensed positioning
information for retrieval at the positioner 11 and/or is displayed.
It will be appreciated that in addition to the binary signal and
the continually sensed positioning information other information
data and data packets such as the diagnostic results can be
included by being modulated on the positioning signal. This
additional information data may relate to an adequate travel
response of the final control element into the desired position,
for instance. But also the distance/time profile of the positioning
motion of the final control element can be coupled to the
positioning signal with the continually sensed positioning
information and the binary signal.
[0034] Via the two-wire line 25 a reverse communication can take
place, namely in the direction of the communication device 15 to
permit, for example, resetting the alarm for the binary signal
generator (not shown).
[0035] The microcomputer 21 may be designed to reduce the
positioning signal S to the continually sensed positioning
information A or to the corresponding signal condition of the
binary signal. In an emergency situation, for instance, at which
only a very low energy supply is available, the microcomputer 21
can reduce the positioning signal just to the binary signal having
a low energy requirement, whereas in normal operating in which
adequate energy is available, the microcomputer 21 can either leave
the positioning signal S unchanged or make the reduction to at
least the continually sensed positioning information.
[0036] Referring now to FIG. 2 there is illustrated a time profile
of the positioning signal S.sub.AB. The stepped basic profile of
the positioning signal S.sub.AB is induced by the binary signal B
whilst the continually sensed digital positioning information A is
generated by frequency modulation in superimposing it on the binary
signal B in making use of the HART protocol.
[0037] While a preferred embodiment has been illustrated and
described in detail in the drawings and foregoing description, the
same is to be considered as illustrative and not restrictive in
character, it being understood that only the preferred embodiment
has been shown and described and that all changes and modifications
that come within the spirit of the invention both now or in the
future are desired to be protected.
* * * * *