The general channel operations test procedure is as follows:
The troubleshooting tools available include:
Note: Occasional communication errors are to be expected. Frequent occurrence or conditions that persist through trip delay periods indicate problems.
Symptoms of channel operation problems include:
The most common causes of PLC operation problems are:
Network scan time (related to latency) is longer than the application assumed. From Alarmware™ with the RTU online, choose menu item Diagnostics, and select "Net Diagnostics Summary Report". In the resulting report, scroll to read the Net 1 scan time within the section of the report for Net 1. Or, use key code 902 11 to determine the PLC network scan time. Then under Configuration | Devices, select the Protocol tab and enter an appropriate Communication Alarm Delay. An entry of twice the reported scan time is a good starting value. Note that network scan time is strongly affected by the number of active channels being scanned. Therefore you can get the best reading of scan time and make the best determination of an optimum Com Alarm Delay to set, after the basic configuration of the RTU has been done.
Other RTU configuration parameters, such as phone numbers, trip delays, or Destination Channel Groupings, are not correct.