Running a FB once per day

Hello all,


I'm still a beginner on all of this, but trying my best.
I have been searching, but not been able to find any good tip on how I should define a FB in OB1 so that it only run once / day at a specific time.


I was thinking on using SFC1 and from there set it to run at a specific time (12:00:00). However I would only like it to run once and not maybe 10 times during the 1 second when set time is true.
Basically what the function should do is subtract value X from value Y and write the answer to Z. I do know how to make that function, but I thought I give this as a reference for what I'm building. It should basically say what the production have been during the day.



I'm using a Siemens S7-313C and Step 7 v5.6

There are OB's designed specifically for this. I believe OB10 is one of them. Search for "Time of day interrupt" for more specific info on them

An older post with a link to some example code that could help:


https://www.plctalk.net/qanda/showpost.php?p=350126&postcount=2

If it don't need be accurate to milliseconds, then read PLC clock time. Convert to hour, minutes and seconds and compare them to wanted clock time, then run FB with En-input and R_trig.

simjon71 said:

There are OB's designed specifically for this. I believe OB10 is one of them. Search for "Time of day interrupt" for more specific info on them

Click to expand...

Thanks a lot, I believe this is exactly what I was looking for.