Specifications

RailCorp Engineering Manual — Signals — Equipment Manual
Cerberus Level Crossing Monitor Field Equipment Manual TMG E1261
© RailCorp Page 20 of 89
Issued August 2012 UNCONTROLLED WHEN PRINTED Version 2.1
Continuously repeat the following:
Turn led 3 off.
If a valid command has been received on serial port A then turn on led 3, process the
command and respond.
If a valid command has been received on serial port B then turn on led 3, process the
command and respond.
Report changes to serial port A if requested.
If required hang-up the modem on port A.
Report changes to serial port B if requested.
Send lamp diagnostic information to serial port if requested.
Report any outstanding status changes.
Check remote test outputs and indicate problems.
Scan task description
Execution of this task is commenced by task 1. It then proceeds in the following manner:
Initialise variables.
Configure level crossing monitor.
Log stop date from non-volatile memory.
Log start date from Real Time Clock.
Continuously repeat the following at 0.25 second intervals:
Turn led 4 on.
Check Real Time Clock.
Kick over watch dog.
Scan inputs, update state, and log changes.
Scan timers, update state, log changes, and every fourth time update run time.
As necessary and every fourth time:
Evaluate expressions.
Scan outputs, log changes, and write outputs.
Scan analogue inputs, update status, and log changes.
Every fourth time.
If not maintenance disabled and their has been a status change then store the time of the
change and set the status to report flag for task 1.
If their is a communications link on serial port A and there has not been a valid message
sent or received for the last 10 minutes then force the modem to be hung-up.