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M91-2-R1 communication error

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It is for M91-2-R1 to stop the program in the PLC using a combination of keys?
Or somehow erase the program from the PLC.
Since I PLC will not communicate with the PC.






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If you go into information mode for the PLC you can get into system settings and go into the system section you should be able to make a PLC change from run to stop or the other way around.  However I have never encountered a program where the act of running the program stopped the PC communications, however first time for everything.  If you stop the PLC and are able to communicate then the program is what caused your problem.


Good Luck


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The only way to stop the program, that I know of, is through the Information Mode or by command from a PC that is online with the PLC. The one exception would be if the Watchdog timer were to expire. Another possibility would be if the PLC battery is bad and there was a power failure (I think you only lose RAM values in the M91, not the program [not sure off the top of my head], but that may be enough to cause your problem).


From a hardware standpoint, other than the battery, the RS232 serial port may have had a failure - or a failure in the connection between the PC and PLC. If you're using a GSM modem to communicate, there are a number of other possibilities to investigate.

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