US3769552A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process control apparatus and method
Assignee: Westinghouse Electric Corp
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Filing: 1972-07-05
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Granted: 1973-10-30
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Expires: 1992-07-05
Abstract
Abstract A process control apparatus and method in which an adjustable control signal is continuously applied to a process control transducer while components of the printed circuit control system are removed for repair or modification. By transferring to manual control by an output driver card, the controller card which provides the signals for the regulator mode of operation may be removed and replaced by a service card. A manual signal generated by the service card is matched with that of the driver card before transfer to the service card is effected and the driver card is removed. An automatic reset feature on the service card precludes inadvertent transfer as the card is plugged in. The manual setting on the driver card may be controlled from a remote station for process control purposes, or from the service card when installed for matching signals when the driver card is replaced. No extra plug-in units are required in the printed circuit rack since the service card replaces the controller card.
Inventors
- 👤 H Cook
- 👤 J Sutherland
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:12
CPC Classifications
G; G05; G05B; G05B9/00; G05B9/02; G05B9/03
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
323 words
Process control apparatus including: a printed circuit board rack assembly including first and second plug-in units and an output circuit connecting each of said plug-in units to a remotely located process control transducer, a removable printed circuit driver card which plugs into the first plug-in unit, and which includes means for generating control signals for the process control transducer, said driver card having a regulator mode of operation wherein it generates a control signal as a function of an applied signal and a manual mode of operation wherein it generates a manually adjustable control signal, a removable printed circuit service card which plugs into said second plug-in unit, said service card having means for generating a control signal for the process control transducer, and manually adjustable means for controlling the magnitude of the control signal, transfer means having a first part mounted on the driver card and operative between a normal condition wherein the control signal generated by the driver card is connected to the output circuit through the first plug-in unit, and a service condition wherein the control signal is disconnected from the output circuit, a second part mounted on the service card and operative between a normal condition wherein the signal generated by the service card is disconnected from the output circuit and a service condition wherein the control signal generated by the service card is connected to the output circuit through the second plug-in unit, and control means mounted on the service card and connected directly to the second part of the transfer means and connected to the first part through the first and second plug-in units, said control means being operative to simultaneously operate both the first and second parts of the transfer means between their normal and service conditions, whereby the driver card may be removed for service without interrupting the application of a control signal to the process control transducer by transferring control to the service card.
Claim 2
Dependent Claim
323 words
Process control apparatus including: a printed circuit board rack assembly including first and second plug-in units and an output circuit connecting each of said plug-in units to a remotely located process control transducer, a removable printed circuit driver card which plugs into the first plug-in unit, and which includes means for generating control signals for the process control transducer, said driver card having a regulator mode of operation wherein it generates a control signal as a function of an applied signal and a manual mode of operation wherein it generates a manually adjustable control signal, a removable printed circuit service card which plugs into said second plug-in unit, said service card having means for generating a control signal for the process control transducer, and manually adjustable means for controlling the magnitude of the control signal, transfer means having a first part mounted on the driver card and operative between a normal condition wherein the control signal generated by the driver card is connected to the output circuit through the first plug-in unit, and a service condition wherein the control signal is disconnected from the output circuit, a second part mounted on the service card and operative between a normal condition wherein the signal generated by the service card is disconnected from the output circuit and a service condition wherein the control signal generated by the service card is connected to the output circuit through the second plug-in unit, and control means mounted on the service card and connected directly to the second part of the transfer means and connected to the first part through the first and second plug-in units, said control means being operative to simultaneously operate both the first and second parts of the transfer means between their normal and service conditions, whereby the driver card may be removed for service without interrupting the application of a control signal to the process control transducer by transferring control to the service card.
Claim 3
Dependent Claim
55 words
The apparatus of claim 1 including meter means mounted on the service card, and means for alternately connecting the control signal from the service card and, through the first and second plug-in units, the control signal from the driver card to the meter so that these two signals may be matched before transfer is effected.
Claim 4
Dependent Claim
39 words
The apparatus of claim 2 including means for electricAlly isolating the meter from the control signals so that application of the signals to the meter does not affect the magnitude of the signal applied to the process control transducer.
Claim 5
Dependent Claim
63 words
The apparatus of claim 1 wherein the transfer control means includes reset means operative to force the control means to operate the first and second parts of the transfer means to their normal conditions when the service card is first plugged into said second plug-in unit, whereby transfer to the service card will not be inadvertently made before the signals can be matched.
Claim 6
Dependent Claim
52 words
The apparatus of claim 4 wherein the rack assembly includes a power supply connected to supply power to the printed circuit cards through said first and second plug-in units and wherein said reset means is activated by the application of power as the service card is plugged into the second plug-in unit.
Claim 7
Dependent Claim
85 words
The apparatus of claim 4 wherein the driver card is connected through the first plug-in unit to a remote control and monitoring station incorporating means for transferring the driver card between the regulator and manual modes of operation and for manually adjusting the magnitude of the control signal in the manual mode, said combination including means mounted on the service card and connected to the driver card through the first and second plug-in units for manually adjusting the magnitude of the driver card control signal.
Claim 8
Dependent Claim
87 words
The apparatus of claim 6 including means mounted on the service card and connected to the driver card through the first and second plug-in units for holding the driver card in the manual mode of operation while the service card is plugged into the second plug-in unit, whereby the driver card cannot be inadvertently transferred to the regulator mode from the remote station while the service card is in place and whereby the driver card is forced to the manual mode when it is replaced after servicing.
Claim 9
Dependent Claim
87 words
The apparatus of claim 1 including a controller card which plugs into said second plug-in unit in place of the service card under normal operating conditions and which includes means for generating said applied signal which determines the magnitude of the control signal generated by the driver card when it is operating in the regulator mode from a set point signal and a process variable feedback signal, said combination including means for connecting the applied signal to the driver card through said first and second plug-in units.
Claim 10
Dependent Claim
327 words
Process control apparatus including: a printed circuit board rack assembly including first and second plug-in units and an output circuit connecting each of said plug-in units to a remotely located process control transducer, a removable printed circuit driver card which plugs into said first plug-in unit and which includes means for generating a control signal for said process control transducer, said driver card having a regulator mode of operation wherein it generates a control signal as a function of an applied signal and a manual mode of operation wherein it generates a manually adjustable control signal, means for switching the driver card between the regulator and manual modes of operation, a removable printed circuit controller card which plugs into said second plug-in unit and which generates said applied signal for the regulator mode of operation of the driver card from a set point signal and a process variable feedback signal, means connecting the applied signal from the controller card to the driver card through the first and second plug-in units, a removable printed circuit service card which may be selectively plugged into the second plug-in unit in place of the controller card, and which includes means for generating a control signal for the process control transducer and means for manually adjusting the magnitude of the control signal, and transfer means operative between a normal condition wherein the control signal from the driver card is connected to the output circuit through the first plug-in unit and a service condition wherein the control signal from the service card when plugged into the second plug-in unit in place of the controller card is connected to the output circuit through the second plug-in unit, whereby the driver card may be removed for service without the interruption of a control signal to the process control transducer by switching the driver card to the manual mode of operation, replacing the controller card with the service card and transferring control to the service card.
Claim 11
Dependent Claim
327 words
Process control apparatus including: a printed circuit board rack assembly including first and second plug-in units and an output circuit connecting each of said plug-in units to a remotely located process control transducer, a removable printed circuit driver card which plugs into said first plug-in unit and which includes means for generating a control signal for said process control transducer, said driver card having a regulator mode of operation wherein it generates a control signal as a function of an applied signal and a manual mode of operation wherein it generates a manually adjustable control signal, means for switching the driver card between the regulator and manual modes of operation, a removable printed circuit controller card which plugs into said second plug-in unit and which generates said applied signal for the regulator mode of operation of the driver card from a set point signal and a process variable feedback signal, means connecting the applied signal from the controller card to the driver card through the first and second plug-in units, a removable printed circuit service card which may be selectively plugged into the second plug-in unit in place of the controller card, and which includes means for generating a control signal for the process control transducer and means for manually adjusting the magnitude of the control signal, and transfer means operative between a normal condition wherein the control signal from the driver card is connected to the output circuit through the first plug-in unit and a service condition wherein the control signal from the service card when plugged into the second plug-in unit in place of the controller card is connected to the output circuit through the second plug-in unit, whereby the driver card may be removed for service without the interruption of a control signal to the process control transducer by switching the driver card to the manual mode of operation, replacing the controller card with the service card and transferring control to the service card.
Claim 12
Dependent Claim
50 words
The apparatus of claim 9 including means mounted on the service card and connected to the driver card through the first and second plug-in units for comparing the control signals generated by the two cards so that they may be matched by the manual adjusting means before transfer is effected.
Claim 13
Dependent Claim
30 words
The apparatus of claim 9 including reset means operative to reset the transfer means to the normal condition when the service card is first plugged into the second plug-in unit.
Claim 14
Independent Claim
207 words
A method of maintaining continuous control of a process control system which includes a printed circuit board rack assembly having two plug-in units each connected through a common output circuit to a process control transducer, a removable printed circuit driver card plugged into a first of said plug-in units and having a regulator mode of operation wherein it generates a control signal for the process control transducer as a function of an applied signal and a manual mode of operation wherein it generates a manually adjustable control signal, a removable printed circuit controller card plugged into the second plug-in unit for generating said applied signal and a plug-in service card which generates a manually adjustable control signal, said method comprising the steps of: transferring the driver card to the manual mode of operation wherein it supplies a manually adjustable control signal to the process control transducer through the output circuit connected to the first plug-in unit, removing the controller card from the second plug-in unit, plugging the service card into the second plug-in unit, and simultaneously disconnecting the control signal generated by the driver card from the output circuit and connecting the control signal from the service card to the output circuit through said second plug-in unit.
Claim 15
Independent Claim
207 words
A method of maintaining continuous control of a process control system which includes a printed circuit board rack assembly having two plug-in units each connected through a common output circuit to a process control transducer, a removable printed circuit driver card plugged into a first of said plug-in units and having a regulator mode of operation wherein it generates a control signal for the process control transducer as a function of an applied signal and a manual mode of operation wherein it generates a manually adjustable control signal, a removable printed circuit controller card plugged into the second plug-in unit for generating said applied signal and a plug-in service card which generates a manually adjustable control signal, said method comprising the steps of: transferring the driver card to the manual mode of operation wherein it supplies a manually adjustable control signal to the process control transducer through the output circuit connected to the first plug-in unit, removing the controller card from the second plug-in unit, plugging the service card into the second plug-in unit, and simultaneously disconnecting the control signal generated by the driver card from the output circuit and connecting the control signal from the service card to the output circuit through said second plug-in unit.
Claim 16
Dependent Claim
41 words
The method of claim 12 including the step of manually adjusting the level of the control signal generated by the service card to match the control signal on the driver card before switching from the driver card to the service card.
Claim 17
Dependent Claim
40 words
The method of claim 13 including the step of alternately applying the control signal from the driver card and the control signal from the service card to a signal level indicator to determine when the two control signals are matched.
Claim 18
Dependent Claim
40 words
The method of claim 14 including the step of isolating the signal level indicator from the control signals whereby the step of applying the control signals to the signal level indicator does not affect the magnitude of the control signals.
Claim 19
Dependent Claim
14 words
The method of claim 13 including the final step of removing the driver card.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-29 | 1977-04-30 | 1977-10-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-29 | 1981-04-30 | 1981-10-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-29 | 1985-04-30 | 1985-10-30 | $7700.00 | Window Closed / Lapsed |