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Program stopped

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I have an problem, which never occoured before. I am using PLC M91-2-T2C for simple operation (inpusts are controlling the outputs). During operation PLC stops, on the display it is writen Program Stop. This now already happened twice. PLC was working fine till now over last two years. Any ideas?

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Hi ;


A few things to check :

     Electrical Noise can be an issue.

     Are the PNP outputs  controlling relays  ---- are there suppressors on the relay coils?

    Are the relays controlling other relays or solenoids?  Do they have suppressors?

    Check the relay contacts  visually-  smoky or pitted?  do they arc when switching?   -- replace the relays and add suppression to reduce the kickback.

         ( locate the article about Electrical noise suppression --  and see pinned  top  of this section -- Flyback Diode -- Great advice )

   Check your power supply.

   Also  -- upload the program into U90 Ladder and compare it to the original - ( Memory Glitch)

             -- Check the battery  -- via info Mode -- SB9   1 = Low Battery



Edited by DanT
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