Is it possible to hold timer value in STL programming

torque · Feb 22, 2014

Hi all! Plcs are new to me, pls help.
Is it possible to hold a timer value in stl programming. I need to stop a countdown timer without loosing the value it has reached and then start the timer from the same value. Not restart it from the preselected value.
The plc is Festo compact FC34. I'm using FST 4 software.

Vartile · Feb 24, 2014

Have you read the programming manual of your device?

torque · Feb 24, 2014

Yes i have. And found operands for setting, resetting and checking timers but nothing more.
I'm probably missing something.

geniusintraining · Feb 24, 2014

I know nothing about Festo PLC's and their software, but you should be able to move the value to a register then move it back when you want it to start again? if they do not have a function to stop the timer

Just a WAG

boneless · Feb 24, 2014

It is possible to write a time directly to a timer. But might be more difficult than needed.

What kind of times are we talking about? ms, s or minutes? If you need seconds or minutes I wouldn't mess with a timer, but use an OB with a set cycle time.

torque · Mar 4, 2014

Thank you for your help! Problem solved - i saved the current value of the timer in a flag word and then loaded it back in the timer preset

Lancie1 · Mar 4, 2014

I saved the current value of the timer in a flag word and then loaded it back in the timer preset

You must move the saved "current value" back to the timer's current value (NOT to its Preset value).

If your Festo software provides for Retentive Timers (timers that retain their timed value when not active), then simply use a Retentive timer and your job is finished.

balash · Mar 4, 2014

Lancie1 said:
You must move the saved "current value" back to the timer's current value (NOT to its Preset value)

Since it is countdown timer I would guess it would work even with preset. But yes that is not the way it should be done.

And also yes, one would think that a PLC would have at least one retentive timer

BobB · Mar 5, 2014

Use a counter and a tick?

Is it possible to hold timer value in STL programming

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