System for exchanging encoded messages between stations

Claim 1

A system for exchanging encoded messages between stations connected by a signalling link and a data link, wherein each station is connected to a general time base and includes a control unit, a connection module responsive to said control unit and connected to the signalling and data links, and an address bus and data bus connecting the control unit to the connection module, wherein the signalling and data links are serial multiplex links synchronous with the time base, a time slot in a signalling frame is assigned to each station, and the messages to be transmitted are of different lengths and are contained within an integer number of frames, and wherein each connection module comprises: first means at each connection module for generating a status signal corresponding to its own status to be sent during its respective time slot; a signalling sender circuit responsive to said first means for sending said status signal onto said signalling links; a signalling receiver circuit at each connection module connected to said signalling links for receiving said status signals from other stations; a station status memory at each connection module for storing the status signals of each of said stations received from said signalling receiver circuit; a message send memory for storing a message to be sent when a station is operating as a calling station, said message to be sent containing a plurality of frames of information; counter means, decremented in response to the transmission of each frame of said message to be sent, for indicating the number of frames of said message remaining to be sent, when a station is operating as a calling station; second means responsive to said counting means for producing a signal when the number of frames of said message remaining to be sent is zero; reservation signal generating means, responsive to outputs from said counting means and second means indicating a non-zero content in said counting means, for, when a station is operating as a calling station, generating a reservation signal during the time slot of said calling station and having a duration equal to said plurality of frames of information; third means, responsive to said reservation signal generating means, for sending a reservation bit signal over said signalling links in the respective time slot of said calling station, for receiving said signalling links for a duration of one frame, said reservation bit signal being sent at each frame except when said number of frames remaining to be sent is zero; fourth means, connected to the control unit, for, when a station is operating as a calling station, producing a signal corresponding to the time slot of a called station; fifth means for, when a station is operating as a calling station, sending a calling bit over the signalling link in the time slot of the called station; six the means for, when a station is operating as a called station, producing a signal corresponding to the time slot of the calling station; first addressing means for addressing said message send memory for reading out the message to be sent when a station is operating as a calling station; an output circuit connected to said data links for sending the message read out from said message send memory; a message receiver circuit for receiving message information from said data links when a station is operating as a called station; second addressing means; a message receive memory responsive to said second addressing means for storing means information received by said message receiver circuit, when a station is operating as a called station; seventh means for, when a station is operating as a calling station, producing at the end of each frame of said reservation signal a send timing pulse signal for decrementing said counting means and for activating said reservation signal generating means, first addressing means and message sender circuit, when the number of frames of said message remaining to be sent is non-zero; and eighth means, responsive to said send timing pulse signal produced at the end of each frame of said reservation signal, for, when said number of frames of said message remaining to be sent is zero, producing an end of sending timing pulse signal for activating said message sender circuit in the time slot of the calling station in order to send an odd parity bit after said message information.

Claim 2

A system for exchanging encoded messages between stations connected by a signalling link and a data link, wherein each station is connected to a general time base and includes a control unit, a connection module responsive to said control unit and connected to the signalling and data links, and an address bus and data bus connecting the control unit to the connection module, wherein the signalling and data links are serial multiplex links synchronous with the time base, a time slot in a signalling frame is assigned to each station, and the messages to be transmitted are of different lengths and are contained within an integer number of frames, and wherein each connection module comprises: first means at each connection module for generating a status signal corresponding to its own status to be sent during its respective time slot; a signalling sender circuit responsive to said first means for sending said status signal onto said signalling links; a signalling receiver circuit at each connection module connected to said signalling links for receiving said status signals from other stations; a station status memory at each connection module for storing the status signals of each of said stations received from said signalling receiver circuit; a message send memory for storing a message to be sent when a station is operating as a calling station, said message to be sent containing a plurality of frames of information; counter means, decremented in response to the transmission of each frame of said message to be sent, for indicating the number of frames of said message remaining to be sent, when a station is operating as a calling station; second means responsive to said counting means for producing a signal when the number of frames of said message remaining to be sent is zero; reservation signal generating means, responsive to outputs from said counting means and second means indicating a non-zero content in said counting means, for, when a station is operating as a calling station, generating a reservation signal during the time slot of said calling station and having a duration equal to said plurality of frames of information; third means, responsive to said reservation signal generating means, for sending a reservation bit signal over said signalling links in the respective time slot of said calling station, for receiving said signalling links for a duration of one frame, said reservation bit signal being sent at each frame except when said number of frames remaining to be sent is zero; fourth means, connected to the control unit, for, when a station is operating as a calling station, producing a signal corresponding to the time slot of a called station; fifth means for, when a station is operating as a calling station, sending a calling bit over the signalling link in the time slot of the called station; six the means for, when a station is operating as a called station, producing a signal corresponding to the time slot of the calling station; first addressing means for addressing said message send memory for reading out the message to be sent when a station is operating as a calling station; an output circuit connected to said data links for sending the message read out from said message send memory; a message receiver circuit for receiving message information from said data links when a station is operating as a called station; second addressing means; a message receive memory responsive to said second addressing means for storing means information received by said message receiver circuit, when a station is operating as a called station; seventh means for, when a station is operating as a calling station, producing at the end of each frame of said reservation signal a send timing pulse signal for decrementing said counting means and for activating said reservation signal generating means, first addressing means and message sender circuit, when the number of frames of said message remaining to be sent is non-zero; and eighth means, responsive to said send timing pulse signal produced at the end of each frame of said reservation signal, for, when said number of frames of said message remaining to be sent is zero, producing an end of sending timing pulse signal for activating said message sender circuit in the time slot of the calling station in order to send an odd parity bit after said message information.