MODBUS Interface
Verbatim Owner's Manual F-9
More precisely, an RC will register a COMALARM whenever the following
two conditions are met:
1. The RC is configured with alarmable criteria.
2. All attempts to poll the RC have failed for the COMALARM trip delay
period (code 4907).
For status reports, alarm calls, LED indicators and acknowledgments, the
COMALARMs are treated in the same way as criteria alarms. They are
annunciated in the following manner:
1. The COMALARM message will override any criteria alarm message.
2. The COMALARM message is not user recordable. It always consists of
"Remote Channel Number ZZ Communication Failure Code XXX."
The failure code annunciated by the Verbatim autodialer serves as an aid in
troubleshooting the network problem causing the failure. They are listed in
section F.17.
To further assist in network troubleshooting several diagnostic commands are
provided. It is possible to:
1. Perform a complete network self-test.
2. Read the communications status for any RC.
3. Read and reset the COMALARM count for any RC.
4. Read a list of the last 10 COMALARM codes on the network.
5. List all RCs currently in the COMALARM state.
6. List the nodes (PLCs) on the net that have all of their RCs in the
COMALARM state.
The Verbatim autodialer provides several other features to help the user with
the inevitable complexities of a networked environment. One is the ability to
suspend/resume all queries initiated by the Verbatim autodialer without altering
any RC programming. The status reports will inform the user when a network is
globally disabled in this fashion.
Another diagnostic tool is the front panel Network Status Indicator LED for
each network. Each LED is like a channel which monitors the overall health of
each network. This is accomplished by accumulating all the COMALARM
codes into a single value. The value is compared against a threshold. See code
492 in Section F.16 for details.
If the threshold is exceeded, then the LED will blink and status reports will
annunciate the current value of the network status code. If the network has been
globally disabled the LED is off. Otherwise the LED is steadily ON, indicating
the network is operating within programmed parameters. See Section F.17.
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