reset a CTU counter

batindeko · Nov 28, 2017

Hi all, I'm newbie here to plctalk!

I writing a PLC programm in ladder where I put an output bit to zero during 9s and the same output bit to one during 1s. In the same time I count every pulse until 50 after that value the counter should be reset and stops to count. In my case this never happen in the next scan the counter keeps counting. I don't know how fix this issue or may be there another to do this.
find attach a picture of my ladder programm
thank for every contribution

Olivier

John Morris · Nov 28, 2017

Welcome to the Forum

In order to receive a good response to your question, you will need to provide more information about the programming platform you are using. RSLogix, Siemens, Mitsubishi. ect.

Good luck!!

batindeko · Nov 28, 2017

so I'm working on studio5000 version Logix designer 30.00.00.

renan.musardo · Nov 28, 2017

In the CTU line, try to put a "Not Done" as a pre-requisite of the counter.

CTU.DN Latch_M Counter_Block
---|/|------|/|------------------|CTU|--|

CTU.DN Latch_M
---| |---------------------------(L)--|

CTU.DN
--| |-------------------|MOV 0 -> CTU.Acc|--|

Have you tried something like this?

**This will make stop counting**

Then You can Latch a memory, and block the line, at the same time that you reset the counter.

batindeko · Nov 28, 2017

renan.musardo said:
In the CTU line, try to put a "Not Done" as a pre-requisite of the counter.

CTU.DN Latch_M Counter_Block
---|/|------|/|------------------|CTU|--|

CTU.DN Latch_M
---| |---------------------------(L)--|

CTU.DN
--| |-------------------|MOV 0 -> CTU.Acc|--|

Have you tried something like this?

**This will make stop counting**

Then You can Latch a memory, and block the line, at the same time that you reset the counter.

what do you mean here by latch your memory? I do not really understand which memory

renan.musardo · Nov 28, 2017

SET / Reset memory

Usually ---(S) / ---(R)

But in the Logix 5000 it is "(L)" and "(U)".

(L) = When Latched, stays in state "1" until it receives a "(U)" Unlatch

renan.musardo · Nov 28, 2017

batindeko said:
what do you mean here by latch your memory? I do not really understand which memory

The memory is just a "bit" in the PLC Memory.

Robobob · Nov 28, 2017

Try this. 2 reset options shown.

batindeko · Nov 28, 2017

Robobob said:
Try this. 2 reset options shown.

the picture is not so good. anyway what controls the counterreset in the second option

batindeko · Nov 28, 2017

the timer keep sending a pulse after resetting thereby the counter increments its value again and that is what I'd like to stop

renan.musardo · Nov 28, 2017

batindeko said:
the timer keep sending a pulse after resetting thereby the counter increments its value again and that is what I'd like to stop

That's why you should use the Latched memory.

batindeko · Nov 28, 2017

this is what i did. may be i am doing something wrong because it doesn't work.

John Morris · Nov 28, 2017

batindeko said:
this is what i did. may be i am doing something wrong because it doesn't work.

If you post what you have, it might help to understand what's not going right for you.

batindeko · Nov 30, 2017

renan.musardo said:
That's why you should use the Latched memory.

thank you renan for your help now I go it. the OTL instruction keep the current state and stops the counter
I attach my ladder diagramm code for reseting the counter.

reset a CTU counter

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