S5Time max value

(Step7 & a Siemens 312C)

We, two final year students in engineering from Belgium, want to program steps which have to run longer than the 2h46min max value of S5Time. This is not directly possible with timers in Step7.

We think that a solution might be to use a timer of 60 seconds, combined with a counter, which counts the minutes we want the step to run.

But does anyone know about a way to program this? We're really stuck here...


Thanks in advance!

Why don't you use the IEC timers? SFB3, SFB4 and SFB5.

These do not have the same upper time limit restrictions as the standard S5 timers.

These can be found in the standard library -> System function blocks

Paul

Hello guys;

On top of Paul's IEC timers suggestion, here are 2 solutions I have used in similar situations:
- Run-time meters(SFC2-3-4)
- Reading the real-time clock (SFC1)
Choose the solution that best fits your process.

There is a manual (Standard and system functions) that is installed with Step 7 that will contain all details of programming them.
Hope this helps,
Daniel Chartier

We used the SFB3, which was the easiest to embed in our program.


Thanks!!