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PLC Programming - Anyone good at this?

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  • PLC Programming - Anyone good at this?

    Hey,

    I'm trying to write a ladder program for an Omron 10C1AR-A using the supplied ZEN software.

    Can't seem to get the timers in the simulator to work.

    Trying to write a program to run some equipment in timed sequences, but if the start button is repeatedly pressed it can skip past certain equip. etc.

    Anyone done something like this who'd mind sending the file over?
    Or at a guess know what stupid thing I'm probably overlooking?

    Cheers,

    Doug
    sigpic

  • #2
    Hey Dugy,

    Didnt think there was another PLC person here!!.

    Ok, good news is that ive programmed just about every PLC on the market at some point (Allen Bradley, Siemens, Quantum blah de blah)
    Bad news is...not the Omron!!!

    Quick think....
    Make sure your using unique timer addresses for each timer (if it needs it)
    Check you have used the right syntax (input address ,output coil and time etc etc)

    Is it just using the simulator that the timers dont work? Guess you wont have a chance to test proper without the field devices?

    Id recomment simply making another program up just to test timers.

    something like:-

    ----| |---------------------------------------------------------------------(TMR CNT up)
    Input Bit 5 secs

    ----| |-------------------------------------------------------------------(Latched Output)
    TMR output


    Manually toggle the input bit, and you should be able to see the timer count up or down.

    Least that way you know you have the timer useage right.

    From there onwards you know its a fault in your code. Try disabling bits that reset or hold off/on the timer.

    If the start button is triggering more than one rung at a time, use a rising (or falling) edge debounce input (or oneshot) to stop it happening.
    Dont know how much you know, but as any switch closes you get debounce, just at the point where the contacts are closed/not closed. As the PLC scans approx 100 scans per second, it can capture this debounce, so on one scan the swich is closed, the next its open etc etc. All this in the 1 second it takes to close a switch.

    Other options are to latch/delatch the input. That is drive a output coil from the switch input (which then in turns starts a timer). That way, once its activated, it remains activated until something delatches it (ie the timer cascade or whatever has completed). Therefore stops debounce.


    Fraid its a bit sketchy as I dont know the structure of the Omrons, but guessing they are similar to any other PLC out there. More than likely you`ll find the fault and think DOH!!

    Hope it helps

    Andrew

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    • #3
      Cheers Andrew,

      I went "back-to-basics" this morning and started testing one line at a time
      as you suggested, I have got the timers sorted now.

      Good point on the de-bounce bit, I was going to try a filter circuit....

      I learnt the "principles" of ladder programming at uni, but the tasks we had
      to do were laughable, and that was a year ago.

      I'm in the tricky position at work where normally we out-sourced PLC work,
      but now they want me to look at it, but there's no-one here to ask questions.

      Might have to PM ya a bit, if u don't mind. (To save BUMPing this post all the time.)



      Oh yeah, this is for a sewage treatment plant.....so you can imagine I REALLY wanna get this right the first time.
      sigpic

      Comment


      • #4
        LOL...

        Sewage treatment?? Ahhhhh.

        Used to work in the industry (water distribution and treatment) myself for 3 years in Perth.
        Looked after the metro,goldfields and South west (Albany, Australind Mandurah) SCADA systems and controls.

        Anyway, sure, PM me anytime you want. Sure I can help. Wouldnt be surprised if its communicating with an ABB RTU and/or SCADA, Kingfisher RTU or a Serck RTU/SCADA.

        Cheers

        Andrew

        Comment


        • #5
          That's the only subject I haven't done!
          I'm sure it arn't that hard....

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