Tsps-headphone plug messages

Claim 1

An operator''s position staffing condition indication arrangement for use in a system having a central control unit and a group of operator positions, with a data link having a local terminal coupled to the control unit and a remote terminal coupled to said group, having a transmitter and receiver at each terminal; each position having an N-conductor key bus with keys having contacts to connect a potential to selected conductors of the bus in a code designating the key, the key busses of the positions being scanned by the scanner, which supplies signals to the remote transmitter to send messages identifying the position and the key code; a display buffer having relays with contacts connected to light lamps and to control other functions at the positions, the display buffer relays being operated in response to messages received via the remote terminal receiver, with data designating a position and a function; said arrangement comprising a position indication relay and means to operate it responsive to plugging in of an operator''s headset and release it responsive to unplugging of the headset, the position indication relay having contacts to connect potential to conductors of the key bus for a ''''staffed'''' code, so that a corresponding message is sent to the common control unit via the data link; and an acknowledgement ''''position occupied'''' message is returned; a ''''position occupied'''' display buffer relay which is operated and locked in response to the ''''position occupied'''' message, ''''position occupied'''' contact means operated in response to the ''''position occupied'''' relay being operated, the ''''position occupied'''' contact means being effective to disconnect the potential from the bus for the ''''staffed'''' code while the position indication relay remains operated; means comprising contacts of the position indication relay and said ''''position occupied'''' contact means effective upon release of the position indication relay upon unplugging of the headset to apply potential to conductors of the key bus for an ''''unstaffed'''' code, so that a corresponding message is sent to the common control unit via the data link, and an acknowledgement ''''position not occupied'''' message is returned; means responsive to the ''''position not occupied'''' message to release the ''''positioN occupied'''' relay, which via said ''''position occupied'''' contact means causes the potential to be removed from the key bus for the ''''unstaffed'''' code.