Modbus communications - problems when using Data Exchange

rcrdmcdaniel
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Modbus communications - problems when using Data Exchange

Сообщение rcrdmcdaniel » 30 апр 2018, 16:03

Hi,

I created a barebones program/screen that ONLY displays the SP and temp variables for the 12 control loops. 24 analog numeric tags on one sceen, and there are no other screens. Everything works fine with no comm errors. Once I set up a few tags to perform Data Exchange, however, the comm errors begin immediately. Generally, out of the six Temp Controllers, at least one of them will generate an error every 5 seconds or so. I have masked these failures from the operator by setting the "Hide Comm Error" flag to TRUE.If I were only monitoring the measured values, this would be sufficient, as the temperatures don't vary and I don't need fast update rates. The problem is that the failures sometimes occur when the PLC needs to communicate a new Setpoint, or if I load a new recipe from the touchscreen. There have been instances when the T10A thinks it has changed the setpoint, but it hasn't taken effect because the temperature controller never received the change. The workaround for this is to manually change the temperature to something else, and then change it back to what the recipe value was. However, the operator usually does not know that the failure occurred?

Please help.

I didn't find the right solution from the Internet.

References:-
http://beijerinc.com/support/ix/forum/v ... f=5&t=1414
Business Communication Examples

Thanks



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