Listener function
(receives the following commands from a controller)

• Commands to perform any functions that can be executed by panel key operations (except "POWER" and "SRQ" keys)
• Requests for output of panel setup information
• Requests for output of program information
• Requests for output of data read through digital I/O cards
• Requests for output of devices status.

Talker function (ouptuts the following information)

• Panel setupt information
• Program information
• Digital data read from digital I/O cards
• Divices status

The following three remote signals can be input and output via the remote control signal connector on the scanner rear.

• Ext-trigger (input, TTL level)
  Start signal for control from an external device. Operation starts on falling edge.
• Closed (output, TTL level)
  Relay operation end signal. The delay from the time when the relays close until the CLOSED signal in output can be specified in ms or s units.
• Extend start/extend end
  By specifying one unit as the master and others as slaves, a system can be extended to multiple 7501 Programmable Scanners.