DCE - Frequent modbus device lost comm alarms

[ATrabert]

I have  a customer running DCE 7.8.0 that has frequent modbus lost comm alarms using the 3rd party vendors modbus tcp gateway..  The customer had larger polling intervals/time outs and retries, but I lowered them to 10 mins, 15 sec timeout, 3 retries.

Looking at the messages log, its flooded with messages modbus connection failed/timed out so I assume that's just the end device failing to respond or some other physical layer related issue, not a problem with DCE.

On another note, this is a Virtual DCE server, are these serial port related processes terminating/respawning anything to be concerned with?

Any assistance would be appreciated.

Apr 29 05:42:35 zz-struxureware nbModbusScan: modbus_process_conn_cbk: connect failed - Connection timed out
Apr 29 05:42:35 zz-struxureware nbModbusScan: modbus_process_conn_cbk: open session failed - Connection timed out
Apr 29 05:42:35 zz-struxureware nbModbusScan: async_connect_response: Connect failed retry attempt 0 of 10.
Apr 29 05:42:41 zz-struxureware init: ttyS0 main process (25955) terminated with status 1
Apr 29 05:42:41 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:42:51 zz-struxureware init: ttyS0 main process (25957) terminated with status 1
Apr 29 05:42:51 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:43:01 zz-struxureware init: ttyS0 main process (25960) terminated with status 1
Apr 29 05:43:01 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:43:11 zz-struxureware init: ttyS0 main process (25966) terminated with status 1
Apr 29 05:43:11 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:43:21 zz-struxureware init: ttyS0 main process (25969) terminated with status 1
Apr 29 05:43:21 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:43:31 zz-struxureware init: ttyS0 main process (25977) terminated with status 1
Apr 29 05:43:31 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:43:38 zz-struxureware nbModbusScan: modbus_process_conn_cbk: connect failed - Connection timed out
Apr 29 05:43:38 zz-struxureware nbModbusScan: modbus_process_conn_cbk: open session failed - Connection timed out
Apr 29 05:43:38 zz-struxureware nbModbusScan: async_connect_response: Connect failed retry attempt 1 of 10.
Apr 29 05:43:41 zz-struxureware init: ttyS0 main process (25985) terminated with status 1
Apr 29 05:43:41 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:43:51 zz-struxureware init: ttyS0 main process (25995) terminated with status 1
Apr 29 05:43:51 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:43:55 zz-struxureware nbSNMPScan: failScan: Marking scan of 10.x.x.x with SCAN_FAILED resultcode.
Apr 29 05:44:01 zz-struxureware init: ttyS0 main process (26003) terminated with status 1
Apr 29 05:44:01 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:44:11 zz-struxureware init: ttyS0 main process (26012) terminated with status 1
Apr 29 05:44:11 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:44:21 zz-struxureware init: ttyS0 main process (26020) terminated with status 1
Apr 29 05:44:21 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:44:24 zz-struxureware nbSNMPScan: failScan: Marking scan of 10.x.x.x with SCAN_FAILED resultcode.
Apr 29 05:44:31 zz-struxureware init: ttyS0 main process (26036) terminated with status 1
Apr 29 05:44:31 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:44:41 zz-struxureware nbModbusScan: modbus_process_conn_cbk: connect failed - Connection timed out
Apr 29 05:44:41 zz-struxureware nbModbusScan: modbus_process_conn_cbk: open session failed - Connection timed out
Apr 29 05:44:41 zz-struxureware nbModbusScan: async_connect_response: Connect failed retry attempt 2 of 10.
Apr 29 05:44:41 zz-struxureware init: ttyS0 main process (26039) terminated with status 1
Apr 29 05:44:41 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:44:51 zz-struxureware init: ttyS0 main process (26043) terminated with status 1
Apr 29 05:44:51 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:45:01 zz-struxureware init: ttyS0 main process (26046) terminated with status 1
Apr 29 05:45:01 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:45:11 zz-struxureware init: ttyS0 main process (26048) terminated with status 1
Apr 29 05:45:11 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:45:21 zz-struxureware init: ttyS0 main process (26049) terminated with status 1
Apr 29 05:45:21 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:45:31 zz-struxureware init: ttyS0 main process (26051) terminated with status 1
Apr 29 05:45:31 zz-struxureware init: ttyS0 main process ended, respawning
Apr 29 05:45:41 zz-struxureware init: ttyS0 main process (26052) terminated with status 1
Apr 29 05:45:41 zz-struxureware init: ttyS0 main process ended, respawning

[Valentin_Kozlov · Accepted solution]

Hi!

DCE uses ModbusTCP protocol, so I don't think that showed tty process is related to thix issue.

We had one case with device communication lost issue and it was resolved by decreasing timeout value.

It sounds little strange but it works more stable with lower timeout value, so I can recommend you to play with that.