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GENERAL

A Panel Multiplex system is required to interface each SS1 Central Interlocking with its associated signalman's panel indications and buttons. This specifications based on Mark II Panel Processors to specification BR 1908A being employed in the Central Interlocking.

Output System

The output system comprises one or more output cards each of which drives a group of panel indications, and two output scanners which interface the output cards to the two SS1 Panel Processors. Each output scanner receives messages over a serial link from one of the Panel Processors.

Input System

The input system contains one or more input cards each of which monitors the state of a group of panel button/switch contacts, and two input scanners which interface the input cards to the two SS1.Panel Processors. Each input scanner transmits messages over a serial link to one of the Panel processors.

Serial Links

The four serial links employ asynchronous data transmission and are to EIA standard RS-422-Adated December 1978 with a transmission speed of 2400 baud.

Cyclic Transmission

Messages as defined in Section 2 are to be sent or received via the links on a continuous cyclic basis and hence no provision is required for message acknowledgments.