Serial loop data transmission system

Claim 3

A method of operating a serial loop data communications system as set forth in claim 1 in which said first address information includes a unique combination of digital signals identifying any one of the connected terminals, said status indicia is a digital signal having two states and indicating that the slot contains data for an addressed terminal when in one state and that the slot contains no data for the addressed terminal when in the other state, and said data includes a coded combination of digital signals for conveying data to the addressed terminal.

Claim 4

A method of operating a serial loop data communications system as set forth in claim 1 in which said first address information includes a unique combination of digital signals identifying the beginning of the series of slots at least one of which is exclusively assigned to each of the connected terminals, said status indicia is an digital signal within the slot having two states and indicating when in one state that the slot contains data for the addressed assigned terminal and indicating when in the other state that that slot contains no data for the addressed assigned terminal, and said data includes a coded combination of digital signals for conveying data to the addressed assigned terminal.

Claim 5

A serial loop data communications system for the transmission of data between a central station and a plurality of remote terminal units each directly connected without delay circuits to the serial loop, each of said terminal units includes a control unit for interfacing the loop and a connected terminal and comprises: a central station for receiving and transmitting data messages to terminal units via time limited data slots each of which is selectively provided with a unique combination of address signals identifying any one of the connected terminal units, a status signal having at least two states for indicating in one state that the slot is in use and in another state that the slot is not in use and is available, and coded data signals for conveying data to the addressed terminal unit; a plurality of remote terminal units connected to the serial loop for receiving data from and transmitting data to the central station; each of said remote terminal units including; first means Indicating receipt of a terminal unit address unique to the receiving terminal unit, second means responsive to said first means for receiving the signals from a slot including the unique terminal address, third means responsive to the first means for altering the status signal is a slot including the unique terminal address from the said one state to the said other state if the addressed terminal unit has no data to transmit, fourth means responsive to a received status signal for altering a said received status signal which is in its said other state to its said one state and transmitting signals including address and data in the slot associated with the altered status signal, and fifth means responsive to the said third and fourth means for passing on received signals unaltered when the terminal unit is not generating signals for transmission on the loop.

Claim 6

A serial loop data communications system for the transmission of data between a central station and a plurality of remote terminal units each directly connected without delay circuits to the serial loop, each of said terminal units includes a control unit for interfacing the loop and a connected terminal and comprises: a central station for receiving and transmitting data messages to terminal units via time limited data slots each of which is selectively provided with a unique combination of address signals identifying any one of the connected terminal units, a status signal having at least two states for indicating in one state that the slot is in use and in another state that the slot is not in use and is available, and coded data signals for conveying data to the addressed terminal unit; a plurality of remote terminal units connected to the serial loop for receiving data from and transmitting data to the central station; each of said remote terminal units including; first means Indicating receipt of a terminal unit address unique to the receiving terminal unit, second means responsive to said first means for receiving the signals from a slot including the unique terminal address, third means responsive to the first means for altering the status signal is a slot including the unique terminal address from the said one state to the said other state if the addressed terminal unit has no data to transmit, fourth means responsive to a received status signal for altering a said received status signal which is in its said other state to its said one state and transmitting signals including address and data in the slot associated with the altered status signal, and fifth means responsive to the said third and fourth means for passing on received signals unaltered when the terminal unit is not generating signals for transmission on the loop.

Claim 7

A serial loop data communications system for the transmission of data between a central station and a plurality of remote terminal units each directly connected without delay circuits to the serial loop, each of said terminal units includes a control unit for interfacing the loop and a connected terminal and comprises: a central station for receiving and transmitting data messages to terminal units via a plurality of time limited data slots at least one for each of said plurality of terminals, said slots being preceded by a combination of electric digital signals identifying the beginning of the plurality of slots and each of said slots including a status signal having at least two states for indicating in one state that the slot is in use and in another state that the slot is not in use and is available for any terminal to transmit data via the slot to the central station, and coded data signals for conveying data; a plurality of remote terminal units connected to the serial loop for receiving data from the transmitting data to the central station; each of said remote terminal units including; first means for indicating receipt of the slot assigned to the terminal unit for the receipt of messages from the central station, second means responsive to said first means for receiving signals from the indicated slot, third means responsive to the first means for altering the status signal in the assigned slot from the said one state to the said other state if the terminal assigned to the slot has no data to transmit, fourth means responsive to a received status signal for altering a said received status signal which is in its said other state to its said one state and transmitting signals including the unique address of the terminal unit and data within the slot associated with the altered status signal, and fifth means responsive to the said third and fourth means for passing on the received signal unaltered when the terminal unit is not generating signals for transmission onto the loop.

Claim 8

A serial loop data communications system for the transmission of data between a central station and a plurality of remote terminal units each directly connected without delay circuits to the serial loop, each of said terminal units includes a control unit for interfacing the loop and a connected terminal and comprises: a central station for receiving and transmitting data messages to terminal units via a plurality of time limited data slots at least one for each of said plurality of terminals, said slots being preceded by a combination of electric digital signals identifying the beginning of the plurality of slots and each of said slots including a status signal having at least two states for indicating in one state that the slot is in use and in another state that the slot is not in use and is available for any terminal to transmit data via the slot to the central station, and coded data signals for conveying data; a plurality of remote terminal units connected to the serial loop for receiving data from the transmitting data to the central station; each of said remote terminal units including; first means for indicating receipt of the slot assigned to the terminal unit for the receipt of messages from the central station, second means responsive to said first means for receiving signals from the indicated slot, third means responsive to the first means for altering the status signal in the assigned slot from the said one state to the said other state if the terminal assigned to the slot has no data to transmit, fourth means responsive to a received status signal for altering a said received status signal which is in its said other state to its said one state and transmitting signals including the unique address of the terminal unit and data within the slot associated with the altered status signal, and fifth means responsive to the said third and fourth means for passing on the received signal unaltered when the terminal unit is not generating signals for transmission onto the loop.