ComStream CM601, Installation And Operation Manual

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8-2 Fault Handling, Troubleshooting, and Maintenance
Fault Reporting
You, the operator, set the faults that are to be monitored and reported, as well as
the conditions under which fault messages appear. Once set, these fault conditions
are monitored and reported by the rear panel status relay connector and their
corresponding fault messages are displayed on a remote terminal or front panel.
Specifying Faults to be Monitored and Reported
Three commands are used to specify which faults will be monitored and reported:
Current Fault Overlay Mask (FO) — specifies the fault conditions that are to
be monitored and reported by the rear panel status relay. The FO parameter is
set to the sum of the bit weights of the selected faults.
Fault Relay Sense (FR) — specifies whether a current fault condition is
reported on the status relay as a contact between the normally closed or
normally open contact pairs of the Form C status relay.
Fault conditions include not only user-specified fault conditions set with the
FO command, but also power failure, power switch turned off, and unplugged
unit faults.
Fault Relay Sense External Signal Polarity (FRX) — specifies how the
CM601 will interpret the external faults that are monitored by the relay sense
pins. The FRX parameter defines whether a fault condition is a closed relay
contact or an open relay contact for each of the three relay sense pins.
Conditions for Remote Fault Messages
If a fault condition is detected by the CM601, an unsolicited fault message is
displayed on the remote terminal only for systems using ASCII remote protocol.
Depending upon the AL setting, an unsolicited ST 0 message may also appear
when the fault no longer exists. The AL command is used to enable or disable
fault reporting and to prevent unsolicited fault messages from being issued to the
remote terminal.
For example, assume that the receive signal has become too weak to detect.
If AL = 0 or 3, a query would have to be issued to discover the fault.
If AL = 1, the CM601 would automatically display several demodulator fault
messages on the remote terminal.
Now assume that the demodulator gains sync.
If AL = 0 or 1, an unsolicited
ST 0
would appear on the remote terminal.
If AL = 3, a query would have to be issued to discover that the faults no longer
exist.