EP0033228A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Industrial control system
Assignee: Forney International Inc
•
Filing: 1981-01-22
•
Granted: —
•
Expires: 2001-01-22
Abstract
Abstract AAcontrol system for controlling an industrial process includes a plurality of remotely located process control units (remotes) each coupled to an associated input/output device(s) and adapted to communicate with one another through a dual channel communications link. The system permits each of the remotes to assume supervisory control of the communications link on a master-for-the-moment basis with the remotes communicating with each other over the communications link by simultaneously sending redundant blocks of information over each of the dual channels of the communications link. The receiving remote tests the validity of the received messages by first selecting one of the two channels and providing an acknowledgement (ACK) if the received information on the first-selected channel is valid. If the information on the first-selected channel is invalid, the receiving remote then selects and tests the validity of the information on the other, alternate channel. If the information received on the other, alternate channel is valid, an acknowledgement is sent to the transmitting remote, and, if the information received on both channels is invalid, a non-acknowledgement (NAK) is sent to the transmitting remote to request retransmission of the invalidly received information. Other features include performing the information validity check on alternate channels of the communications link with each successive transmission of information, providing redundant remotes for detecting the failure of one of the controlling remotes and for assuming control responsibility thereover; observing the status of the controlled devices and recording changes in that status along with the pertinent time-of-day information; and detecting an open or degraded portion in either of the dual channels of the communications link and inserting a line terminating impedance on either side of the open or degraded portion of the channel.
Inventors
- 👤 Billy R. Slater
- 👤 Michael E. Cope
- 👤 Candelario Paredes
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-26 06:31
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/40; H04L12/40169; H04L12/40176; H04L12/40195; G; G05; G05B; G05B19/00; G05B19/02; G05B19/04; G05B19/042; G05B19/0428; G06; G06F; G06F11/00; G06F11/07; G06F11/16; G06F11/20; G06F11/202; G06F11/2023; G06F11/2025; G06F11/2041; G06F11/22; H04B; H04B17/00; H04B17/40; H04L1/00; H04L1/12; H04L1/16; H04L1/1607; H04L1/1628; H04L1/24; H04L1/242; H04L1/243; H04L12/407; H04L12/417; G05B2219/00; G05B2219/20; G05B2219/25; G05B2219/25154; G05B2219/25161; G05B2219/25163; G06F11/2205; G06F11/2294; H04L2012/4026
Claims Analysis
Total Claims: 38
Claim 1
Independent Claim
153 words
A system for controlling a process, said system including a plurality of process controlling remotes interconnected by a common communications link, said system comprising: at least one process controlling remote for transmitting process control information in digital form, said information'arranged in information groups of predetermined format and including an error detecting code word; at least one other process controlling remote for receiving process control information in said information groups and testing the validity of the received groups based on said error detecting code word; the communication link interconnecting said first-mentioned and said second-mentioned remotes including at least two independent communication channels, said first-mentioned remote transmitting identical information groups on each of said channels, said second-mentioned remote testing the validity of the received information groups on each communications channel and concluding the information transfer transaction if the received information group on at laast one of said plural communication channels passes its validity check test.
Claim 2
Independent Claim
153 words
A system for controlling a process, said system including a plurality of process controlling remotes interconnected by a common communications link, said system comprising: at least one process controlling remote for transmitting process control information in digital form, said information'arranged in information groups of predetermined format and including an error detecting code word; at least one other process controlling remote for receiving process control information in said information groups and testing the validity of the received groups based on said error detecting code word; the communication link interconnecting said first-mentioned and said second-mentioned remotes including at least two independent communication channels, said first-mentioned remote transmitting identical information groups on each of said channels, said second-mentioned remote testing the validity of the received information groups on each communications channel and concluding the information transfer transaction if the received information group on at laast one of said plural communication channels passes its validity check test.
Claim 3
Dependent Claim
84 words
The industrial process control system claimed in claim 1, wherein: said second-mentioned remote includes responding means for transmitting an acknowledgement signal to said first-mentioned remote when the information group received over a first-selected communication channel is valid, for transmitting an acknowledgement signal to said first-mentioned remote when the information group received over said other selected communication channel is found valid, and for transmitting a non-acknowledgement signal to said first-mentioned remote when the information group received over said other selected communication channel is found invalid.
Claim 4
Dependent Claim
29 words
The industrial process control system claimed in claim 2, wherein: the non-acknowledgement signal from said second-mentioned remote to said first-mentioned remote causes retransmission of said invalidly received information group.
Claim 5
Dependent Claim
29 words
The industrial process control system claimed in claim 1, wherein: said first-mentioned remote is adapted to transmit said information groups at least twice in succession on each communication channel.
Claim 6
Dependent Claim
44 words
The industrial process control system claimed in claim 4, further comprising: means associated with said second-mentioned remote which, in part, tests the validity of the plural information groups received on a communications channel by effecting a comparison between the first-received and the second-received group.
Claim 7
Dependent Claim
220 words
An information transfer system for transmitting digital information between active devices and testing the validity of the transmitted information, said system comprising: at least one active device for transmitting information in digital form; at least one other active device for receiving information in digital form; at least a first and a second independent communication channel connected to and extending between said first-mentioned and said second-mentioned devices for conveying information therebetween; a transmitter means associated with said first-mentioned active device for transmitting digital information arranged in blocks of predetermined format, said transmission means transmitting, for each information transfer transaction, an identical block on each of said first and second communication channels; receiving means associated with said second-mentioned active device for receiving digital information transmitted by said first-mentioned active device and for selecting a one of said first and second communication channels and testing the validity of the received block and, when said received block from said first-selected communication chanel is found invalid, for selecting the other of said first and second communication channels and testing the validity of the received block on said other communication channel; and means associated with said receiver means for first-selecting the first of said communication channels on alternate information transfer transactions and for first-selecting the second of said communication channels on the remaining information transfer transactions.
Claim 8
Dependent Claim
220 words
An information transfer system for transmitting digital information between active devices and testing the validity of the transmitted information, said system comprising: at least one active device for transmitting information in digital form; at least one other active device for receiving information in digital form; at least a first and a second independent communication channel connected to and extending between said first-mentioned and said second-mentioned devices for conveying information therebetween; a transmitter means associated with said first-mentioned active device for transmitting digital information arranged in blocks of predetermined format, said transmission means transmitting, for each information transfer transaction, an identical block on each of said first and second communication channels; receiving means associated with said second-mentioned active device for receiving digital information transmitted by said first-mentioned active device and for selecting a one of said first and second communication channels and testing the validity of the received block and, when said received block from said first-selected communication chanel is found invalid, for selecting the other of said first and second communication channels and testing the validity of the received block on said other communication channel; and means associated with said receiver means for first-selecting the first of said communication channels on alternate information transfer transactions and for first-selecting the second of said communication channels on the remaining information transfer transactions.
Claim 9
Independent Claim
119 words
A method for transferring digital information formatted in predetermined blocks between an information transmitting device and an interconnected information receiving device, said method comprising the steps of: transmitting identical information blocks from a transmitter over plural independent communication channels to a receiver; receiving and storing the received information blocks at the receiver; selecting the information block received on one of said plural communication channels and testing the validity thereof; -selecting the information block received on the other of said communication channels and testing the validity thereof in the event the first-selected information block fails its validity check; and requesting retransmission of said information blocks in the event both the first-selected and the second-selected information blocks fail their validity test.
Claim 10
Independent Claim
119 words
A method for transferring digital information formatted in predetermined blocks between an information transmitting device and an interconnected information receiving device, said method comprising the steps of: transmitting identical information blocks from a transmitter over plural independent communication channels to a receiver; receiving and storing the received information blocks at the receiver; selecting the information block received on one of said plural communication channels and testing the validity thereof; -selecting the information block received on the other of said communication channels and testing the validity thereof in the event the first-selected information block fails its validity check; and requesting retransmission of said information blocks in the event both the first-selected and the second-selected information blocks fail their validity test.
Claim 11
Dependent Claim
33 words
The method claimed in claim 7, wherein said first-selection step further comprises the step of transmitting an acknowledgement signal from the receiver to the transmitter when the first-tested information block is found valid.
Claim 12
Dependent Claim
34 words
The method claimed in claim 8, wherein the second selection step further comprises the steps of transmitting an acknowledgement signal from the receiver to the transmitter when the second-tested information block is found valid.
Claim 13
Dependent Claim
33 words
The method claimed in claim 9, wherein the requesting step further comprises the step of transmitting a non-acknowlegement signal from the receiver to the transmitter when the second-tested information block is found invalid.
Claim 14
Independent Claim
146 words
A method for transferring digital information formatted in predetermined blocks between an information transmitting device and an interconnected information receiving device, said method comprising the steps of: transmitting, for each information transfer transaction, identical information blocks from a transmitter over plural independent communication channels to a receiver; receiving and storing the received information blocks at the receiver; selecting the information block received on one of said plural communication channels and testing the validity thereof; selecting the information block received on other of said plural communication channels and testing the validity thereof in the event the first-selected information blocks fails its validity check; and requesting retransmission of said information blocks in the event both the first-selected and said second-selected information blocks fail their validity test, said one communication channel first-selected on alternate information transfer transactions and said other communication channel first-selected on the remaining information transfer transaction.
Claim 15
Independent Claim
146 words
A method for transferring digital information formatted in predetermined blocks between an information transmitting device and an interconnected information receiving device, said method comprising the steps of: transmitting, for each information transfer transaction, identical information blocks from a transmitter over plural independent communication channels to a receiver; receiving and storing the received information blocks at the receiver; selecting the information block received on one of said plural communication channels and testing the validity thereof; selecting the information block received on other of said plural communication channels and testing the validity thereof in the event the first-selected information blocks fails its validity check; and requesting retransmission of said information blocks in the event both the first-selected and said second-selected information blocks fail their validity test, said one communication channel first-selected on alternate information transfer transactions and said other communication channel first-selected on the remaining information transfer transaction.
Claim 16
Dependent Claim
208 words
.12. In a control system for controlling an industrial process of the type that includes a plurality of remote units each connected to an associated input/output device and interconnected through a communications link and in which each remote is assigned a unique position in a predetermined succession order, 0, 1, 2, 3,...m,...n, and in which each remote accepts supervisory control of the communications link on a master for the moment basis in accordance with the succession order, a method for transferring supervisory control of the communications link from a present system master R m to the first successive remote R m+1 comprising the steps of: transmitting a control-transfer command signal through the communications link from the present system master R m to the next successive remote R m+1 ; evaluating the validity of the control-transfer command signal at the next successive remote R m+1 ; sending an acknowledgement signal through the communications link from the next successive remote R m+1 to the present system master R when the control-transfer command signal is found valid; and accepting supervisory control of the communications link by the next successive remote R m+1 from the present master R m whereby the next successive remote R m+1 becomes the present master R .
Claim 17
Dependent Claim
208 words
.12. In a control system for controlling an industrial process of the type that includes a plurality of remote units each connected to an associated input/output device and interconnected through a communications link and in which each remote is assigned a unique position in a predetermined succession order, 0, 1, 2, 3,...m,...n, and in which each remote accepts supervisory control of the communications link on a master for the moment basis in accordance with the succession order, a method for transferring supervisory control of the communications link from a present system master R m to the first successive remote R m+1 comprising the steps of: transmitting a control-transfer command signal through the communications link from the present system master R m to the next successive remote R m+1 ; evaluating the validity of the control-transfer command signal at the next successive remote R m+1 ; sending an acknowledgement signal through the communications link from the next successive remote R m+1 to the present system master R when the control-transfer command signal is found valid; and accepting supervisory control of the communications link by the next successive remote R m+1 from the present master R m whereby the next successive remote R m+1 becomes the present master R .
Claim 18
Dependent Claim
322 words
In a control system for controlling an industrial process of the type that includes a plurality of remote units each connected to an associated input/ output device and intercoonnected through a common communications link and in which each remote is assigned a unique position in a predetermined succession order, 0, 1, 2, 3,... m,...n, and in which each remote accepts supervisory control of the communications link on a master for the moment basis and in which each remote includes.a settable variable transfer-monitor timer, a method for sequentially transferring supervisory control of the communications link from the present master R m to the next successive remote R m+1 in the succession order and for transferring supervisory control of the communications link from the present system master R to the second successive remote R m+2 in the event the next successive remote R m+1 fails to accept supervisory control from the present system master R m comprising the steps of: transmitting a control-transfer command signal through the communications link from the present system master R m to the next successive remote R m+1 ; setting the transfer-monitor timer of at least the second successive remote R m+2 to a time-out interval based on a function of the successive remote's position relative to the present system master R m ; evaluating the validity of the control-transfer command signal at the next successive remote R m+1 ; sending an acknowledgement signal through the communications link from the next successive remote R m+1 to the present system master R m when the control-transfer command signal is found valid; accepting supervisory control of the communications link by the first successive R m+1 from the present system master; and accepting supervisory control of the communications link by the second successive remote R m+2 when the transfer-monitor timer of the second successive remote R m+2 times-out before the first successive remote R m+1 accepts supervisory control of the communications link.
Claim 19
Dependent Claim
322 words
In a control system for controlling an industrial process of the type that includes a plurality of remote units each connected to an associated input/ output device and intercoonnected through a common communications link and in which each remote is assigned a unique position in a predetermined succession order, 0, 1, 2, 3,... m,...n, and in which each remote accepts supervisory control of the communications link on a master for the moment basis and in which each remote includes.a settable variable transfer-monitor timer, a method for sequentially transferring supervisory control of the communications link from the present master R m to the next successive remote R m+1 in the succession order and for transferring supervisory control of the communications link from the present system master R to the second successive remote R m+2 in the event the next successive remote R m+1 fails to accept supervisory control from the present system master R m comprising the steps of: transmitting a control-transfer command signal through the communications link from the present system master R m to the next successive remote R m+1 ; setting the transfer-monitor timer of at least the second successive remote R m+2 to a time-out interval based on a function of the successive remote's position relative to the present system master R m ; evaluating the validity of the control-transfer command signal at the next successive remote R m+1 ; sending an acknowledgement signal through the communications link from the next successive remote R m+1 to the present system master R m when the control-transfer command signal is found valid; accepting supervisory control of the communications link by the first successive R m+1 from the present system master; and accepting supervisory control of the communications link by the second successive remote R m+2 when the transfer-monitor timer of the second successive remote R m+2 times-out before the first successive remote R m+1 accepts supervisory control of the communications link.
Claim 20
Dependent Claim
152 words
In a control system of the type having a plurality of process control remotes interconnected through a communications link with each remote assigned a unique position in a predetermined succession order and each remote exericising supervisory control of the communication link on a revolving master basis, a method for transferring supervisory control of the communications link from a present system master to the next successive remote in the succession order comprising the steps of: transmitting a control-transfer command signal along the communication link from the present system master to the next successive remote in the succession order; receiving and evaluating the validity of the control-system command signal at the next successive remote; and accepting supervisory control of the communication link by the next successive remote from the present master if the control-transfer command signal is found valid by the next successive remote, whereby the next successive remote becomes the present system master.
Claim 21
Dependent Claim
152 words
In a control system of the type having a plurality of process control remotes interconnected through a communications link with each remote assigned a unique position in a predetermined succession order and each remote exericising supervisory control of the communication link on a revolving master basis, a method for transferring supervisory control of the communications link from a present system master to the next successive remote in the succession order comprising the steps of: transmitting a control-transfer command signal along the communication link from the present system master to the next successive remote in the succession order; receiving and evaluating the validity of the control-system command signal at the next successive remote; and accepting supervisory control of the communication link by the next successive remote from the present master if the control-transfer command signal is found valid by the next successive remote, whereby the next successive remote becomes the present system master.
Claim 22
Dependent Claim
220 words
An improved industrial process control system with provision for logging change-in-status information, said system of the type having a plurality of controlled devices and associated sensors each having input/putput data associated therewith, said controlled devices and associated sensors interconnected through a communications link, and a computer-based controlling means for effecting control thereof, the improvement comprising: first and second memory files for storing input/output data associated with said controlled device and sensors, said second memory of a predetermined size and of the first-in first-discard type; scanning means for obtaining the input/output data associated with each of said controlled devices and sensors and storing the so-obtained data in said first memory and thereafter obtaining the input/output data on a cyclic basis; comparing and detecting means for comparing the input/output data obtained during the latest of said cyclic scans with the input/output data stored in said first memory file, and, in the event a difference between the latest obtained data and the stored data is detected indicating a change-in-status, updating the appropriate input/output data in said first memory and storing information relating to th so-detected change-in-status in said second memory on a first-in first-discard basis; means at least responsive to selected ones of said input/output data or combinations thereof for providing an inhibit signal to said second memory to inhibit further storage therein.
Claim 23
Dependent Claim
220 words
An improved industrial process control system with provision for logging change-in-status information, said system of the type having a plurality of controlled devices and associated sensors each having input/putput data associated therewith, said controlled devices and associated sensors interconnected through a communications link, and a computer-based controlling means for effecting control thereof, the improvement comprising: first and second memory files for storing input/output data associated with said controlled device and sensors, said second memory of a predetermined size and of the first-in first-discard type; scanning means for obtaining the input/output data associated with each of said controlled devices and sensors and storing the so-obtained data in said first memory and thereafter obtaining the input/output data on a cyclic basis; comparing and detecting means for comparing the input/output data obtained during the latest of said cyclic scans with the input/output data stored in said first memory file, and, in the event a difference between the latest obtained data and the stored data is detected indicating a change-in-status, updating the appropriate input/output data in said first memory and storing information relating to th so-detected change-in-status in said second memory on a first-in first-discard basis; means at least responsive to selected ones of said input/output data or combinations thereof for providing an inhibit signal to said second memory to inhibit further storage therein.
Claim 24
Dependent Claim
216 words
An industrial process control system, said system comprising: a plurality of controlled devices and associated sensors for effecting process control of each controlled device and sensor having input/output data points associated therewith; computer based controller means connected to said controlled devices and sensors for effecting control thereover; a communications link interconnecting said computer base controllers for effecting communication therebetween; each controller including a first memory means and a second memory means, said second memory means of the first-in first-discard type; scanning means for scanning said data points and obtaining the input/output data associated with each of said controlled devices and sensors and storing the so-obtained data in said first memory and thereafter scanning the input/ output data points on a cyclic basis; comparing and detecting means for comparing the input/output data obtained during the latest scan with the input/output data stored in said first memory file and, in the event a difference between the latest obtained data and the stored data is detected indicating a change-in-status, updating the appropriate input/output data in said first memory and storing information relating to the so-detected change-in-status in said second memory; and means at least responsive to selected ones of said input/output data or combinations thereof for providing an inhibit signal to said second memory to inhibit further storage therein.
Claim 25
Dependent Claim
216 words
An industrial process control system, said system comprising: a plurality of controlled devices and associated sensors for effecting process control of each controlled device and sensor having input/output data points associated therewith; computer based controller means connected to said controlled devices and sensors for effecting control thereover; a communications link interconnecting said computer base controllers for effecting communication therebetween; each controller including a first memory means and a second memory means, said second memory means of the first-in first-discard type; scanning means for scanning said data points and obtaining the input/output data associated with each of said controlled devices and sensors and storing the so-obtained data in said first memory and thereafter scanning the input/ output data points on a cyclic basis; comparing and detecting means for comparing the input/output data obtained during the latest scan with the input/output data stored in said first memory file and, in the event a difference between the latest obtained data and the stored data is detected indicating a change-in-status, updating the appropriate input/output data in said first memory and storing information relating to the so-detected change-in-status in said second memory; and means at least responsive to selected ones of said input/output data or combinations thereof for providing an inhibit signal to said second memory to inhibit further storage therein.
Claim 26
Dependent Claim
213 words
An improved method of operating an industrial process control system to obtain a historical log of change-in-status events occurring within the system, the system of the type that includes a plurality of controlled devices and sensors each having scannable input/ output data, computer-based controller means that includes memory means, and a communications link for effecting interconnection therebetween, the improved method comprising the steps of: (a) scanning the input/output data of said controlled devices and sensors and storing the so-obtained input/output data in a first memory file; (b) subsequentially scanning the input/ output data of said controlled devices and sensors and comparing the subsequentially obtained data with the data in the first memory file; (c) detecting differences between the subsequentially obtained data and the data in the first memory file; (d) updating, in the event that a difference between the subsequentially obtained data and the data in the first memory file is detected, the appropriate data in the first memory file and storing information relating to the detected differences in a second memory of the first-in first-discard type; (e) inhibiting the second memory file from further storage therein in the event of the occurrence of a predetermined condition or conditions with the system; and (f) repeating steps (b) through (e) on a cyclic basis.
Claim 27
Dependent Claim
213 words
An improved method of operating an industrial process control system to obtain a historical log of change-in-status events occurring within the system, the system of the type that includes a plurality of controlled devices and sensors each having scannable input/ output data, computer-based controller means that includes memory means, and a communications link for effecting interconnection therebetween, the improved method comprising the steps of: (a) scanning the input/output data of said controlled devices and sensors and storing the so-obtained input/output data in a first memory file; (b) subsequentially scanning the input/ output data of said controlled devices and sensors and comparing the subsequentially obtained data with the data in the first memory file; (c) detecting differences between the subsequentially obtained data and the data in the first memory file; (d) updating, in the event that a difference between the subsequentially obtained data and the data in the first memory file is detected, the appropriate data in the first memory file and storing information relating to the detected differences in a second memory of the first-in first-discard type; (e) inhibiting the second memory file from further storage therein in the event of the occurrence of a predetermined condition or conditions with the system; and (f) repeating steps (b) through (e) on a cyclic basis.
Claim 28
Independent Claim
180 words
A system for controlling an industrial process, said system including a plurality of process controlling remotes each interconnected by common communications link and adapted to test the communications integrity of the communications link between remotes and provide an impedance thereto in the event of an interruption or degradation of the communications integrity of the communications link between remotes, said system comprising: a plurality of process controlling remotes interconnected through a communications link, each remote provided with (a) means for transmitting and receiving digital information in messages of predetermined format to and from each of the other remotes within the system, (b) message checking means for determining if the so- transmitted messages are successfully received, and (c) impedance means selectively connectable to said communications link by said remote through a selectively actuable switch means; each remote adapted to transmit messages to other of said remote(s) and provide an actuation signal to said switch means to connect said impedance means to said communications link if the number of messages successfully received by said other of said remote(s) is below a predetermined threshhold.
Claim 29
Independent Claim
180 words
A system for controlling an industrial process, said system including a plurality of process controlling remotes each interconnected by common communications link and adapted to test the communications integrity of the communications link between remotes and provide an impedance thereto in the event of an interruption or degradation of the communications integrity of the communications link between remotes, said system comprising: a plurality of process controlling remotes interconnected through a communications link, each remote provided with (a) means for transmitting and receiving digital information in messages of predetermined format to and from each of the other remotes within the system, (b) message checking means for determining if the so- transmitted messages are successfully received, and (c) impedance means selectively connectable to said communications link by said remote through a selectively actuable switch means; each remote adapted to transmit messages to other of said remote(s) and provide an actuation signal to said switch means to connect said impedance means to said communications link if the number of messages successfully received by said other of said remote(s) is below a predetermined threshhold.
Claim 30
Independent Claim
160 words
A method of providing a line-matching impedance in a communications link of an industrial process control system having a plurality of process controlling remotes interconnected by the communications link in the event of an interruption or degradation of the communications integrity of the communications link comprising the steps of: providing at least one of said remotes with an impedance means that is selectively connectable to the communications link; transmitting a message from the first-mentioned remote to a receiving remote; evaluating the validity of the message received at the second-mentioned remote and sending a valid-message-received message from the second-mentioned remote to the first-mentioned remote if the test message is valid; evaluating the communications integrity of the communications link between the first- and second-mentioned remote as a function of a number.of valid-message-received messages received by the first-mentioned remote; and connecting said impedance means to said communications link if the number of valid-messages-received by the first-message remote is less than a predetermined value.
Claim 31
Independent Claim
160 words
A method of providing a line-matching impedance in a communications link of an industrial process control system having a plurality of process controlling remotes interconnected by the communications link in the event of an interruption or degradation of the communications integrity of the communications link comprising the steps of: providing at least one of said remotes with an impedance means that is selectively connectable to the communications link; transmitting a message from the first-mentioned remote to a receiving remote; evaluating the validity of the message received at the second-mentioned remote and sending a valid-message-received message from the second-mentioned remote to the first-mentioned remote if the test message is valid; evaluating the communications integrity of the communications link between the first- and second-mentioned remote as a function of a number.of valid-message-received messages received by the first-mentioned remote; and connecting said impedance means to said communications link if the number of valid-messages-received by the first-message remote is less than a predetermined value.
Claim 32
Independent Claim
224 words
A method of providing a line matching impedance in a communications link of an industrial process control system having a plurality of remotes R 0 ' R 1 ,...R x-1 , R x , R x+1 ...R n-1 , R interconnected by a common communications link in the event of an interruption or degradation of the communications integrity of the communications link, comprising the steps of: (a) providing at least one of said remotes R x with the impedance means that is selectively connectable to said communications link; (b) transmitting a test message from the remote R x to a selected one of the remotes R x+1 or R x-1 ; (c) evalulating the validity of the test message sent to said selected one remote from the remote Rx (d) responding to a validly received message by said selected one remote by transmitting a valid-message-received message to the remote R x ; (e) evaluating the communications integrity of the communications link between the remote R and the selected one remote as a function of the valid-messages-received messages by the remote R x ; (f) connecting the impedance means to the communications link when the number of valid-messages-received messages is below a predetermined value; and (g) repeating the steps (b) through (f) for the other one of the remotes R x+1 or R x-1 .
Claim 33
Independent Claim
224 words
A method of providing a line matching impedance in a communications link of an industrial process control system having a plurality of remotes R 0 ' R 1 ,...R x-1 , R x , R x+1 ...R n-1 , R interconnected by a common communications link in the event of an interruption or degradation of the communications integrity of the communications link, comprising the steps of: (a) providing at least one of said remotes R x with the impedance means that is selectively connectable to said communications link; (b) transmitting a test message from the remote R x to a selected one of the remotes R x+1 or R x-1 ; (c) evalulating the validity of the test message sent to said selected one remote from the remote Rx (d) responding to a validly received message by said selected one remote by transmitting a valid-message-received message to the remote R x ; (e) evaluating the communications integrity of the communications link between the remote R and the selected one remote as a function of the valid-messages-received messages by the remote R x ; (f) connecting the impedance means to the communications link when the number of valid-messages-received messages is below a predetermined value; and (g) repeating the steps (b) through (f) for the other one of the remotes R x+1 or R x-1 .
Claim 34
Dependent Claim
322 words
A distributed process control system comprising a plurality of primary control units interconnected by a communications link, each of said primary control units having a central processing unit and a plurality of input/output devices connected thereto, said input/output devices sensing the condition of and controlling the operation of a process, the central processing unit of each of said primary control units containing a stored applications program which responds to the condition of input devices connected thereto and control the output devices connected thereto in accordance with said applications program, each of said primary control units being operable to receive data from and transmit data to each of the other primary control units over said communications link, at least one redundant control unit connected to said communications link and operable to receive data from and transmit data to each of said primary control units connected to said communications link, said redundant control unit comprising a central processing unit with a stored program and comprising means to monitor said primary control units and to respond to the central processing unit of one of said primary control units failing to carry out its stored applications program, to carry out such applications program in the central processing unit of the redundant control unit, said redundant control unit receiving data from said one of said primary control units representing the condition of the input and output devices of the primary control unit over said communications link and sending instructions to said one of said primary control units to direct changes in the output devices of the primary control unit in accordance with such applications program being carried out in said redundant control unit, each primary control unit including means to respond to instructions received from said redundant control unit over said communications link directing changes in the output devices of such primary control unit to effect corresponding changes in the output devices of such primary control unit.
Claim 35
Dependent Claim
322 words
A distributed process control system comprising a plurality of primary control units interconnected by a communications link, each of said primary control units having a central processing unit and a plurality of input/output devices connected thereto, said input/output devices sensing the condition of and controlling the operation of a process, the central processing unit of each of said primary control units containing a stored applications program which responds to the condition of input devices connected thereto and control the output devices connected thereto in accordance with said applications program, each of said primary control units being operable to receive data from and transmit data to each of the other primary control units over said communications link, at least one redundant control unit connected to said communications link and operable to receive data from and transmit data to each of said primary control units connected to said communications link, said redundant control unit comprising a central processing unit with a stored program and comprising means to monitor said primary control units and to respond to the central processing unit of one of said primary control units failing to carry out its stored applications program, to carry out such applications program in the central processing unit of the redundant control unit, said redundant control unit receiving data from said one of said primary control units representing the condition of the input and output devices of the primary control unit over said communications link and sending instructions to said one of said primary control units to direct changes in the output devices of the primary control unit in accordance with such applications program being carried out in said redundant control unit, each primary control unit including means to respond to instructions received from said redundant control unit over said communications link directing changes in the output devices of such primary control unit to effect corresponding changes in the output devices of such primary control unit.
Claim 36
Dependent Claim
152 words
A distributed process control system as recited in claim 21, wherein said system includes a plurality of redundant control units each serving as a back-up for a different set of primary control units, each of said redundant control units being operable to receive data from and transmit data to each of said primary control units and each of aid other redundant control units over said communications link, each of said redundant control units comprising a central processing unit with a stored program and comprising means to monitor the primary control units for which said redundant control unit serves as a back-up and operating in response to the central processing unit of one of said primary control units for which such redundant control units serves as a back-u p failing to carry out its stored applications program, to carry out such applications program in the central processing unit of such redundant control unit.
Claim 37
Dependent Claim
97 words
A distributed process control system as recited in claim 21, wherein said primary control units and said redundant control units include means to cause said control units to take turns being master of said communications link with each of said control units being operable when master of said communications link to receive and transmit data to any other of said control units and being operable when not master of said communications link to only receive and transmit data over said communications link in response to instructions from the control units that is master of said communications link.
Claim 38
Dependent Claim
82 words
A distributed process control system as recited in claim 21, wherein said communications link is operable to transmit data between said control units in the form of data blocks, each of said control units including means operable in response to receiving an information data block from a sending control unit over said communications link to transmit an acknowledgement data block over said communications link to said sending control unit to indicate receipt by the receiving control unit of said information data block.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.