Problem: I’m implementing a motor monitoring system where the TRB245 sends SMS notifications based on motor status (running/failure) received from a PLC via Modbus TCP.
The issue is that since the PLC inputs are latched, the alarm condition remains active continuously, causing the SMS trigger to fire repeatedly and spam the notification recipients.
If you want to only be informed ONCE, in the “Services → Modbus → Modbus TCP Client → (edit) → Alarm Configuration → (edit)” menu, you can set “Action frequency” to “First trigger”:
Alternatively, if you want to be informed periodically (e.g. once an hour), you can enable the “Redundancy protection” and set your own time period how often this alarm could be triggered:
Hi, I tried using those configurations for the alarm, but the problem is that I don’t want the SMS to be sent only once—I need it to be sent every time the trigger occurs. Since Modbus is continuously reading, the condition is always true and it keeps sending SMS messages over and over.
I think the best solution is to detect the rising edge in the PLC, link it to another memory bit, and then read that bit via Modbus to trigger the alarm. That way, the SMS is sent only on the rising edge.
By the way, is it possible to send a notification through the RMS app instead of an SMS?
This way, you should be able to set the action frequency to “Every trigger” so that the notification is sent only when the condition changes rather than continuously.
