adccommunitymod (AutomationDirect) asked a question.
Lookout direct question 205 plc
Created Date: January 07,2003
Created By: ddecourt
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Im driving a 205 plc with lookout direct, and rather new to all of this. My problenm is I need to know how to have the PLC realize if comunication with the PC is lost and stop running. setting values back to default at startup >
Created Date: January 07,2003
Created by: ddecourt
Im driving a 205 plc with lookout direct, and rather new to all of this. My problenm is I need to know how to have the PLC realize if comunication with the PC is lost and stop running. setting values back to default at startup>
Created Date: January 07,2003
Created by: Tom Jenkins
If you really REALLY want to do this, the easiest way is to have the Lookout send some varying data to the PLC - I usually use a clock based register like seconds or such. In the PLC have the new value stored and periodically compare it to the last value received. If they are the same then you have lost communications. If they are different then move the just received value to replace the previous one. I usually use a counter so that several tests in a row have to be bad before I trip an alarm so one bad communication won't shut you down.