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Modbus Com driver lost after timeout

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LO 6.6 running on Win XP

 

We have 5 RTUs running over a slow radio linkage.  All works OK until there is a radio timeout or other com glitch. The modbus begins normal polls and sometimes recovers OK, however other times, it begins sending junk and never recovers.  Only a LO restart clears the problem.  An example trace is attached, but here is the last few

 

10:24:31.3 - Modbus1 ->
[3C][04][00][00][00][03][B4][E6]
10:24:36.5 - Modbus1 <-
[3C][04][06][2B][2B][69][EA][15][96][FC][89]
10:25:04.1 - Modbus5 ->
[40][02][00][00][00][05][B7][18]
10:25:30.7 - Modbus5 ->
[40][02][00][00][00][05][B7][18]

 

Here...each of the 5 RTUs are polled, then the following starts:

 

10:32:41.3 - Modbus5 ->
[3A][34][30][30][32][30][30][30][30][30][30][30][35][42][39][0D][0A]
10:32:49.2 - Modbus5 ->
[40][02][00][00][00][05][B7][18]
10:32:57.0 - Modbus5 ->
[3A][34][30][30][32][30][30][30][30][30][30][30][35][42][39][0D][0A]
10:33:04.8 - Modbus5 ->
[40][02][00][00][00][05][B7][18]
10:33:12.6 - Modbus5 ->
[3A][34][30][30][32][30][30][30][30][30][30][30][35][42][39][0D][0A]
10:33:20.5 - Modbus5 ->
[40][02][00][00][00][05][B7][18]
10:33:28.3 - Modbus5 ->
[3A][34][30][30][32][30][30][30][30][30][30][30][35][42][39][0D][0A]
10:33:36.1 - Modbus5 ->
[40][02][00][00][00][05][B7][18]
10:33:44.0 - Modbus5 ->
[3A][34][30][30][32][30][30][30][30][30][30][30][35][42][39][0D][0A]

 

 

This continues until LO is restarted, then everything is OK.

 

Why is the Modbus driver sending this garbage message: [3A][34][30][30][32][30][30][30][30][30][30][30][35][42][39][0D][0A]

 

It looks like ASCII text with a LF/CR at the end, like a modem init string.  Our COM line is hardwired, no modem is involved.

 

Thanks in advance.


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