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'Comm Fail' value for Modbus tag

Question asked by kbobeck on Sep 13, 2017
Latest reply on Sep 14, 2017 by kbobeck

We've just installed the Modbus Ethernet interface and have created a test tag. It seems to be working, except once in a while it gets a 'Comm Fail' status come through.


TimestampVoltage Reading
13-Sep-17 11:04:55467
13-Sep-17 11:07:51466
13-Sep-17 11:08:54465
13-Sep-17 11:10:52466
13-Sep-17 11:11:53467
13-Sep-17 11:18:52467
13-Sep-17 11:19:55465
13-Sep-17 11:20:54467
13-Sep-17 11:21:52467
13-Sep-17 11:22:55Comm Fail
13-Sep-17 11:23:55465
13-Sep-17 11:24:55466
13-Sep-17 11:25:52467
13-Sep-17 11:34:56466
13-Sep-17 11:35:54466
13-Sep-17 11:44:51466
13-Sep-17 11:45:54467
13-Sep-17 11:46:57Comm Fail
13-Sep-17 11:47:51467
13-Sep-17 11:49:31467


Looking at the Device Status health point, the status has remained as 'Good' both times the 'Comm Fail' occurred.


How is 'Comm Fail' different than I/O Timeout? Definitions I've found for both essentially say that the interface couldn't communicate with the device. However, the Modbus Ethernet user manual only addresses what can cause and how to reduce I/O Timeouts.