Industrial control system with interconnected remotely located computer control units
First Claim
1. 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;
plural independent communication channels connected to and extending between said first-mentioned and said second-mentioned active devices for conveying information therebetween;
said first-mentioned active device including a transmission means for transmitting digital information arranged in blocks of predetermined format, said transmission means transmitting an identical block on each of said plural communication channels; and
said second-mentioned active device including receiving means for receiving digital information transmitted by said first-mentioned active device and for selecting one of said plural communication channels and testing the validity of the received block and, when said received block from said first-selected communication channel is found invalid, for selecting another of said plural communication channels and testing the validity of the received block on said other communication channel.
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Accused Products
Abstract
A control 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. Each remote has a unique succession number within a predetermined succession order with supervisory communication-control of the communication link sequentially transferred to each remote according to its succession number to provide a revolving or master for the moment control of the system. Digital information in the form of data and control information blocks is transmitted between the remotes with the blocks transmitted twice on each channel of the communications link. The destination remote tests the block validity on one of the two dual channels and, if validated, responds with an acknowledgement signal (ACK) and, if invalid, tests the blocks on the other, alternate channel and then responds with an acknowledgement or non-acknowledgement signal (NAK) depending upon whether the data blocks tests on the alternate channel are found valid or invalid. A non-acknowledgement from the destination remote re-triggers the transmission of the blocks from the source remote. The system provides high overall operating efficiency since the remotes will maintain a system-like integrity on each side of a severed communication link and the redundant block transmission with alternate line checking provides very high information transfer reliability.
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Citations
45 Claims
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1. An information transfer system for transmitting digital information between active devices and testing the validity of the transmitted information, said system comprising:
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at least one active device for transmitting information in digital form; at least one other active device for receiving information in digital form; plural independent communication channels connected to and extending between said first-mentioned and said second-mentioned active devices for conveying information therebetween; said first-mentioned active device including a transmission means for transmitting digital information arranged in blocks of predetermined format, said transmission means transmitting an identical block on each of said plural communication channels; and said second-mentioned active device including receiving means for receiving digital information transmitted by said first-mentioned active device and for selecting one of said plural communication channels and testing the validity of the received block and, when said received block from said first-selected communication channel is found invalid, for selecting another of said plural communication channels and testing the validity of the received block on said other communication channel. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. An information transfer system for transferring digital information between stored-program controlled means and for testing the validity of the transferred information, said system comprising:
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at least one stored-program controlled means for transmitting digital information in blocks of predetermined format which blocks include an error detecting code word; at least one other stored-program controlled means for receiving digital information in said block format and adapted to test the validity of said received block using the error detecting code word; plural independent communication channels connected to and extending between said first-mentioned and said second-mentioned stored-program controlled means for transferring information blocks therebetween; and said second-mentioned stored-program controlled means having validity testing means for selecting a one of said plural communication channels and testing the validity of the block received thereon and for selecting another of said plural communication channels and testing the validity of the block received on said other communication channel when the block received on said first-selected communication channel fails its validity test. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A system for controlling an industrial process, said system including a plurality of process controlling remotes each connected by a common communications link, said system comprising:
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at least one process controlling remote for transmitting process control information in digital form, said information arranged in groups of predetermined format with each of said information groups including an error detecting code word; at least one other process controlling remote for receiving process control information in said information group format and testing the validity of the received blocks based on said error detecting code; the communication link interconnecting said first-mentioned and said second-mentioned remotes including at least two independent communication channels, said first-mentioned remote transmitting an identical information group on each of said communication channels, said second-mentioned remote operable to select a one of said communication channels and evaluate the validity of said received information group and select the other of said communication channels when the received information group on said first-selected communication channel fails its validity test. - View Dependent Claims (16, 17, 18, 19, 20, 21)
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22. A system for controlling a process, said system including a plurality of process controlling remotes interconnected by a common communications link, said system comprising:
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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 communication channel and concluding the information transfer transaction if the received information group on at least one of said plural communication channels passes its validity check test. - View Dependent Claims (23, 24, 25, 26, 27)
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28. 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:
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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. - View Dependent Claims (29, 30, 31, 32, 33, 34)
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35. 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 exercising 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:
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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-transfer command signal at the next successive remote; sending an acknowledgement signal to the present system master from the next successive remote and accepting supervisory control of the communications 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. - View Dependent Claims (36, 37)
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38. In a control system of the type having a plurality of process control remotes interconnected through a communications link with each remote assigned the unique position in a predetermined succession order and each remote exercising supervisory control of the communication link on a revolving master basis, each remote having a variable transfer monitor timer, a method for transferring supervisory control of the communication link from one remote to another comprising:
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transmitting a control-transfer command signal along the communication link from the present system master to the next successive remote in the succession order; setting, when said control-transfer command signal is transmitted from the present system master to the next successive master, the transfer-monitor time-out interval of at least the second successive remote from the present master to a time-out interval that is a function of a predetermined supervisory control transfer value and the position of the particular remote relative to the present master said method operating in a normal mode comprising the further steps of; (1) receiving and evaluating the validity of the control transfer command signal at the next successive remote; (2) sending an acknowledgement signal to the present system master from the next successive remote; and (3) accepting supervisory control of the communications link by the next successive remote from the present system 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, said method operating in an abnormal mode comprising the further step of accepting supervisory control of the communications link by the second successive remote from the present system master in the event the transfer-monitor timer of such second successive remote times out before the first successive remote accepts supervisory control in said normal mode of operation.
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39. 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 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 Rm to the first successive remote Rm+1 comprising the steps of:
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transmitting a control-transfer command signal through the communications link from the present system master Rm to the next successive remote Rm+1 ; evaluating the validity of the control-transfer command signal at the next successive remote Rm+1 ; sending an acknowledgement signal through the communications link from the next successive remote Rm+1 to the present system master Rm when the control-transfer command signal is found valid; and accepting supervisory control of the communications link by the next successive remote Rm+1 from the present master Rm whereby the next successive remote Rm+1 becomes the present master Rm.
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40. In a control system for controlling an industrial process of the type that includes a plurality of remote units each connected to an input/output device and interconnected 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 Rm to the next successive remote Rm+1 in the succession order and for transferring supervisory control of the communications link from the present system master Rm to the second successive remote Rm+2 in the event the next successive remote Rm+1 fails to accept supervisory control from the present system master Rm comprising the steps of:
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transmitting a control-transfer command signal through the communications link from the present system master Rm to the next successive remote Rm+1 ; setting the transfer-monitor timer of at least the second successive remote Rm+2 to a time-out interval based on a function of the successive remote'"'"'s position relative to the present system master Rm ; said method in a normal mode of operation comprising the further steps of; (1) evaluating the validity of the control-transfer command signal at the next successive remote Rm+1 ; (2) sending an acknowledgement signal through the communications link from the next successive remote Rm+1 to the present system master Rm when the control-transfer command signal is found valid; and (3) accepting syspervisory control of the communications link by the first successive Rm+1 from the present system master; said method in an abnormal method of operation comprising the further step of; accepting supervisory control of the communications link by the second successive remote Rm+2 when the transfer-monitor timer of the second successive remote Rm+2 times-out before the first successive remote Rm+1 accepts supervisory control of the communications link.
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41. 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 exercising 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:
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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.
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42. A system for controlling an industrial process, said system comprising:
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a plurality of process controlling remotes, a common communication link interconnecting said remotes, each remote being assigned a unique position in a predetermined succession order and each remote exercising supervisory control of the communication link on a master for a moment basis in accordance with the succession order; each remote including a means for transmitting digital information in block format over said communications link to the other of the remotes and each including receiver means for receiving digital information transmitted from one other of the remotes; and each remote including means for transferring the supervisory control to the next successive remote in the succession order by transmitting a control-transfer block over said communication link to the next successive remote in the succession order and the next successive remote accepting supervisory control of the communication link in response to said control-transfer block. - View Dependent Claims (43, 44, 45)
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Specification