Multiple Counters

I am wanting to control a flip-flop state of two outputs with counters. I want to have 3 different time states that i can select. I have programmed it with the counter and it works fine. When I put it into my real program and set it up three times, each with a different input select and different counter, only one will work. And that one is always the one that I type in last. I thought with set and reset I could use the same outputs multiple times but is this the problem? Double coil effect? I would appreciate any help!

You SHOULD be able to use SET and RESET (or LATCH and UNLATCH) several places in your program.

Not sure what is wrong though.

ZIP your code and ATTACH it. Then we can have a closer look.

NB: A little more details about PLC and software type would also help.

I agree with Jesper - posting your code will help.

My first thought is that it certainly sounds like double-coiling.

Marc

multiple counters

First I am using an IDEC Micro Smart 25 plc with a micro I/O touch screen. I have converted the latter to a pdf file so you should be able to view it. Again thanks for all help given, I appreciate it.

Yes, it is almost certainly a double coil problem!

In fact, most PLC programmers consider it bad practice to have any bit (internal or external) switched on in more than one part of the program, unless (in very rare circumstances) it is absolutely necessary.

A lot of programmers (myself included) also try to avoid using SET/RESET instructions because it is much harder to keep track of what's going on during debugging.

So, what do you use in its' place?
My preferred method is self latching (sealing) the output to the device. For example, the first three outputs in your program might be coded:

---] [-------]/[---+---]/[------(OUT)

  M0000     I0003  ¦  I0001     Q0000

                   ¦

                   ¦

---] [-------------+

  Q0000





---] [---+---]/[---+------(OUT)

  I0001  ¦  I0002  ¦      Q0001

         ¦         ¦

         ¦         ¦     +-----+

---] [---+         +-----+T0000¦

  Q0001                  ¦ 0003¦

                         +-----+



            +-----+

---] [------+T0000¦

  I0002     ¦ 0005¦

            +-----+



---] [---+---]/[------(OUT)

  T0000  ¦  T0001     Q0002

         ¦

         ¦

---] [---+

  Q0002

Now, I'm not saying this would work for you but if it didn't, I'm sure you could troubleshoot it a lot easier.

As for flip-flopping outputs, the traditional method is:

|   INPUT                  ONE-SHOT

|----] [---------------------(  )

|

|  ONE-SHOT    OUTPUT       OUTPUT

|----] [---------]/[-----+---(  )

|                        |

|  OUTPUT      ONE-SHOT  |

|----] [---------]/[-----+

I don't know the specifics of the Idec PLC instruction for a 'one-shot' but I expect there will be either a PuLSe or DiFU or something like that.
So far as the timers and counters are concerned, I would suggest you re-examine your code and look at implementing them, based on these methods.

Anthony

Thanks, everyone. It was double coil syndrone. I used interal coils in the program I had and now it works fine. I now have printed this thread and am looking at using the suggestions to inprove my program. Again, Thanks.

Danco59

danco59,

good idea to print to a PDF file. Then not only those with the IDEC programming software can have a look also.