Hello Everybody!

I am not an experienced PLC Programmer, sorry for that beginner question.

There is a project where will be 3 different programs and each program has 15-20 Steppes and in each steps, I have to control different valves (about 5-8 in each) with delay one after another.

The delay has to be the same time, for example, 5 seconds. I setting an output (valve_01) true, then waiting for 5s, then setting another output (valve_02), and so on...

I thought I could use the same timer and when time is over I just reset it and use it again in the next step.

I would like to make an FB, that can I use several times for the same process, just setting the different outputs (controlled valves) and doing the same thing...  But It doesn't work.
Of course, I could solve it with different timers, but if you multiply it (3 programs * 15 steppes * 5 valves) at least 225 Timers for the same purpose, counting down from 5 seconds is meaningless and I think that is not the proper solution. 

So how should I use the timer or what another opportunity I have if I don't want to waste memory?

Thank you for your help and sorry for my bad english and beginner question.

Hello deadandan,

regarding to your enclosed picture I see by all timers TON the same instance-DB. I recommend to use for each timer the separate instance-DB.

In STEP 7 (TIA Portal) you can also use FBs with the language S7-GPAPH. This is better to program the sequence via step by step with delays. See in this case the examples of the FAQ:

How do you delay transition of steps as a function of the interlock in STEP 7 (TIA Portal)?
https://support.industry.siemens.com/cs/ww/de/view/61595891

deadandan

So how should I use the timer or what another opportunity I have if I don't want to waste memory?

You can't call one timer multiple times in the code in this fashion - it gets confused what you want 

Call it only once - preferably after your state machine. To make it countdown properly, it must see a rising edge each time it has to start - i.e. next step starts. It means you need additional steps in between existing steps, so the timer can see "0" at IN, just for one scan, before it sees "1" again.

Hello.

You can use just one timer to count your 5 seconds and change step number every 5 seconds after you start your sequence.

You can count 5 seconds, increase a variable value by 1 (Step counts), reset the timer and do it over again, then compare the step counter value and trigger the valve you desire to trigger on specific step.

Regards.

Cicero

Hello deadandan,

regarding to your enclosed picture I see by all timers TON the same instance-DB. I recommend to use for each timer the separate instance-DB.

In STEP 7 (TIA Portal) you can also use FBs with the language S7-GPAPH. This is better to program the sequence via step by step with delays. See in this case the examples of the FAQ:

How do you delay transition of steps as a function of the interlock in STEP 7 (TIA Portal)?
https://support.industry.siemens.com/cs/ww/de/view/61595891

With best regards
Cicero

Hello Cicero,

thank you for your suggestions!
Unfortunately S7-GRAPH only in S7-1500 available, but now I'm working with S7-1200.. But yes, you are right, that was the first that I have checked when I got the project. Haha.

Yes, in that example I am using the same instance DB (by the way Multi-instance), but I am bothered about the as I mentioned the memory if I using different DB-s for each Timer.

But as I am writing these lines, I think about that, it would be problematic to use too many Timers, but to be more exact: using too many Timers --> DBs --> Memory, right?

Rescobedo

Hello.

You can use just one timer to count your 5 seconds and change step number every 5 seconds after you start your sequence.

You can count 5 seconds, increase a variable value by 1 (Step counts), reset the timer and do it over again, then compare the step counter value and trigger the valve you desire to trigger on specific step.

Regards.

 Hello Rescobedo!

Do you mean, something like "outsourcing" the timing and getting back with the increased value (Step counts)?

Sounds good, I will try it!

Thanks for your suggestion!

jacek d

 

deadandan

So how should I use the timer or what another opportunity I have if I don't want to waste memory?

You can't call one timer multiple times in the code in this fashion - it gets confused what you want 

Call it only once - preferably after your state machine. To make it countdown properly, it must see a rising edge each time it has to start - i.e. next step starts. It means you need additional steps in between existing steps, so the timer can see "0" at IN, just for one scan, before it sees "1" again.

 Hello, jacek d!

Sadly I don't understand very well, how you mean to control the timer with edges?
I would appreciate it if you could make me an example with pictures about it because I really like to control with edges!

Thanks a lot!

Hope it's self-explaining.

jacek d

Hope it's self-explaining.

 It is!
Thank you!