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denise01

Holding Relays

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Hi Wonder if anybody can help me. I have to start logging at certain times to log all shift output across 3 shifts, to start I use inputs HR contacts which are timed through Supervisor to be forced on and off at the start and end of each shift only trouble is if the PLC CJ1M looses power then I have to force the contacts on and off myself does anybody know how I can alleviate this problem. Regards Peter

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It sounds like you are doing a 1-shot from CX-Supervisor to the PLC, ie. at 8:00, turn on HR10.00? Is the time setting variable from CX-Supervisor? Why not make the time value setting writeable to the PLC, then PLC code (which is evaluated every scan) can compare this value with the PLC Clock, and will return the bit state, depending on the shift time. Know need for a HR then either.

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Hi thanks for the suggestion, could you please tell me what sort of code I would use to turn the bits on and off at certain times. Regards Peter

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Ladder logic would be the easiest Depending if you want control down to the minute level or not, but simple > < type instructions would be the way to go. I think that certain models have the PLC clock Hours/Minutes combined into 1 BCD word, you could do a comparison with this, and turn on the bit as the result. Give it a go, if you can't work it out, post back and we can setup a basic example.

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Hi am I right in thinking that for CJ1M I would use the Bit word A531 and use this as a compare eg greater than o6oo to start and less than 1400 to switch off. Regards Peter

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