S7 FP in Function block problem

Hi guys,

I have a problem with one shot fp when using it in FB. Fp variable is declared as a stat variable. For some reason it isn't one shot. It stays in true condition fot the same time as the triggering bit. I tried to use temp variable also, but no result. With merker address it works fine, but is should be a variable.

I passed this problem by making the pulse manually with help pulse bit, but still wondering why the fp doesn't work. More confusing is the thing I have used stats as a fp in fb before, but now it doesn't work. Is it another siemens problem or is it just me.. ?

Thanks in advance!

I always do it like this

A sCondition
FP sHelpflag
= sOSP

sHelpflag is of static but is not the oneshot it self but the memory flag of the previous sCondition.

So sHelpflag is high when sCondition is high. sOSP is oneshot positive flank whn sCondition is on and sHelpflag is off.

Miika - If the one shot works with a marker but not with a static variable in an FB, there must be something wrong with your code and it is not a Siemens problem. Maybe the instance DB is out of date or you have an indirect addressing bug - there are quite few possibilities. If the static variable for the one-shot store is being overwritten then what else is being overwritten that you haven't found yet ? You must find out what is going on.