Method and apparatus for transmitting status information between remote locations
First Claim
1. A method of transmitting status information from a first location to a remote second location comprising the steps of:
- At the first location;
(a) monitoring the state of a plurality of devices, each of which is in either an active or inactive state;
(b) assembling a table of digital codes such that a distinct code is associated with each possible state of each said device;
(c) determining the current state of each device and assigning the proper digital code for each device in its current state;
(d) determining if any device has changed from the inactive to the active state;
(e) transmitting in a predetermined sequence the codes for each device;
(f) if a change to the active state has occurred for any device, interrupting said predetermined sequence, to transmit the digital code associated with the device that has changed state;
At the second location;
(g) receiving said digital codes in the order transmitted;
(h) comparing the received code with the table to determine the validity of the received code;
(i) if the received code is valid, decoding the code to determine the device and state represented;
(j) outputting the status information based on the most recent code received;
(k) upon reception of any invalid code, inhibiting output so that no status information is output until validity is reestablished; and
(l) reestablishing validity after the reception of a valid code for each of the monitored devices without reception of an intervening invalid code.
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Accused Products
Abstract
A system for transmitting status information from a first location to a remote second location includes a monitoring device at the first location for monitoring the state of a plurality of relays or other devices that are capable of being in either an active or inactive state. The monitoring device produces a digital signal representative of the state of the relays. A first memory storage device contains a table of digital codes arranged so that a unique code is associated in a predetermined manner with each relay in each state. A processor is provided for processing the digital signal from the monitoring device and for accessing the table to retrieve the code associated with the present state of each relay. The processor also produces a first signal indicative of a change of state of any relay from the inactive to the active state. A transmitter transmits the codes retrieved from the processor in a predetermined sequence. An interrupt device is included that interrupts the transmission sequence in the presence of the first signal to cause the immediate transmission of the code associated with the relay that has changed from the inactive to the active state. A receiver at the remote second location receives the transmitted codes and verifies their validity by comparing the received codes to a table of expected codes contained in a second memory storage device. If the code received is valid, a decoder determines the relay and state represented and formulates and outputs a control word representative of the state of the monitored relays. If the code is invalid, an alarm signal is generated that inhibits the output of a control word. Once an alarm signal is generated, it is maintained until a valid code is received for each of the monitored relays without the reception of an intervening invalid code. Preferably, the transmission and reception of the codes are accomplished under control of a digital computer operating under program control.
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Citations
19 Claims
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1. A method of transmitting status information from a first location to a remote second location comprising the steps of:
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At the first location; (a) monitoring the state of a plurality of devices, each of which is in either an active or inactive state; (b) assembling a table of digital codes such that a distinct code is associated with each possible state of each said device; (c) determining the current state of each device and assigning the proper digital code for each device in its current state; (d) determining if any device has changed from the inactive to the active state; (e) transmitting in a predetermined sequence the codes for each device; (f) if a change to the active state has occurred for any device, interrupting said predetermined sequence, to transmit the digital code associated with the device that has changed state; At the second location; (g) receiving said digital codes in the order transmitted; (h) comparing the received code with the table to determine the validity of the received code; (i) if the received code is valid, decoding the code to determine the device and state represented; (j) outputting the status information based on the most recent code received; (k) upon reception of any invalid code, inhibiting output so that no status information is output until validity is reestablished; and (l) reestablishing validity after the reception of a valid code for each of the monitored devices without reception of an intervening invalid code. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for transmitting status information from a first location to a remote second location, comprising:
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At the first location; first means for monitoring the state of a plurality of devices, each of which can be in either an active or an inactive state and for producing a digital status word representative of the state of the devices; first memory storage means containing a table of digital codes arranged so that a unique code in said table is associated in a predetermined manner with each device in each of its states; second means associated with said first means for processing said digital status word and accessing said first memory storage means to retrieve the digital code associated with the current state of each said device, said second means also producing a first signal indicative of a change of state of any of said devices from the inactive to the active state; transmitter means for receivig said associated digital codes from said second means and transmitting said codes to said second location in a predetermined sequence; interrupt means associated with said second means and said transmitter means and operable upon the presence of said first signal to interrupt the sequence of transmission of said codes to cause the immediate transmission of the code for the device that has changed from the inactive to the active state; And at the second location; receiver means for receiving said transmitted digital codes; second memory storage means containing a table of values representative of said digital codes; verification means associated with said receiver means and said second memory storage means for comparing the received digital codes with said values in said table to determine the validity of said received digital codes and for producing an alarm signal in the event that the received digital code does not match one of said values in said table and maintaining said alarm signal until a valid code is received for each monitored device without an intervening valid code being received; decoder means associated with said receiver means and said comparison means and operable in the absence of said alarm signal to determine the monitored device and state represented by said received digital code; output means associated with said decoder means for producing and outputting a digital control word representative of the state of the monitored devices; and inhibiting means associated with said decoder means and said output means and operable in the presence of said alarm signal to inhibit the output of said digital control word. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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Specification