Call FB without DB (Simatic S7)

Hi All,

Today i came across the following syntax: UC FB 1

as you can see this calls FB 1 without an instance DB.

My question is where are the static variables stored ?

Thanks a lot in advance,

Bart Janisse

In the instance DB open immediately before the UC FB 1

That explains.

Thanks

Also, if its called from within another FB, then it could be sharing the same IDB as the main FB.

PeterW said:

Also, if its called from within another FB, then it could be sharing the same IDB as the main FB.

Click to expand...

LD said that alredy

TurpoUrpo said:

LD said that alredy

Click to expand...

erm.. no he didn't..

You can open a instance DB before unconditionally calling a FB
(as LAR said), or you can ensure the parameters (TEMP excluded) of your secondary FB matches the parameters of another FB up to the point you need, then call the secondary FB unconditionally from within (as I said)


Two totally different methods.

What DB u think is open just before UC in either case. The DB that has stat variables (atleast should have).

LD said intance db open at the moment of UC. It can either be the parent FB:s instance DB (with suitable offset added to AR2 if needed) or another separate instance DB opened before UC.

It also might be one big shared DB with suitable datastructure, opened as IDB, either with added offset or no offset depending on how programmer has wanted to structure the program.

L D[AR2 said:

In the instance DB open immediately before the UC FB 1

Click to expand...