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P3K Sequencer behaviour

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  • P3K Sequencer behaviour

    Found strange behavior of SEQ instruction - after it is done - it goes to step #1 instead (as I understand) stay on a last step until you reset an instruction.
    Any ideas how to keep it on a last step? (except add one more empty step with Boolean var and disable rung with this variable)


  • #2
    If you want to stop on the last step, then setup the limit cycles to = 1. It will run only once, once the last step is complete the done bit will go high. You can then use the reset leg to reset the SEQ to begin again at step one.
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    • #3
      Thank you for reply, but the questing was how to keep SEQ on a last step after it is done. It just switch automatically to step 1 (with all variables from step 1, without reset) when it is done even with limit cycles = 1
      Last edited by svshow; 07-20-2016, 10:55 AM.

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      • #4
        Since we're on the topic of the Sequencer, how can it be made to be event driven, so that every time enable goes high, it just does one step, and stops, waiting for the next off to on transition of enable, instead of time driven? This, so it can work like an Allen-Bradley sequencer.
        If you've done the very best you can, worrying won't make it any better - Walt Disney

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        • #5
          Does/can the SEQ Jog perform like this? I've not used the SEQ instruction.
          Last edited by kewakl; 07-20-2016, 08:14 PM.

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          • #6
            Originally posted by kewakl View Post
            Does/can the SEQ Jog perform like this? I've not used the SEQ instruction.
            That's what I'm thinking. I have a P2K trainer, so I'll just have to try that out.
            If you've done the very best you can, worrying won't make it any better - Walt Disney

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            • #7
              I used Cycle Limit =10 and after its done I see Current cycle =11 (instead 10) and Current step = 1 (instead last step in a sequence)
              Looks like mistake, or I do not understand something...
              Attached Files

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              • #8
                I guess the way I would do it would be to have an extra step at the end that turns off the enable bit into the sequencer instruction. You would probably have to do this in the start value field, as the sequencer instruction is make before break. Are you relying on the done bit from the instruction?

                As for the questions regarding event driven sequencing, that's very easy to set up. See the attached picture
                Attached Files

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                • #9
                  Hi. Found another issue with sequencer. This is definitely mistake most probably in CPU firmware. So:
                  I switched sequencer into minute calculation mode and run it for couple days (one step can take 8-12 hours), and what I see - sequencer shows 500 minutes passed in current step but really 430-440 minutes. Half an hour in 500 minutes it is a lot. I am absolutely sure that I did not update time in PLC, did not pause sequencer (if you pause it - time should be less) during working process. (Using Productivity Suite 2.1.2.1 (do not think it is an issue with Productivity Suite) CPU Scan time 3.5msec).
                  Any ideas?
                  Attached Files
                  Last edited by svshow; 10-03-2016, 08:31 AM.

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