FC/FB only called in OB1?

I need clarification on the calling of FBs and FCs in OB1, Is it alawys a must that FBs and FCs should be called in OB1 in every written program, I have seen a Program where FBs and FCs are not called in OB1, Please help.

------------------------------------------------------------------------------------------
Split from Call FCs from Ob1.

Hello

CBTALI

I need clarification on the calling of FBs and FCs in OB1, Is it alawys a must that FBs and FCs should be called in OB1 in every written program, I have seen a Program where FBs and FCs are not called in OB1, Please help.

There is no rule that says OB1 must be used. Then follows that the calling of code blocks (FC / FB) does not need to happen in OB1.

It is a requirement (concentrating on Siemens PLCs) that there be some starting point for the code execution. This starting point is always some OB (organizational block). The most popular and well known OB is OB1.

It would do you a world of good if you get hold of a manual or study the in-software help for which OBs are available to you.   ..unless you already know this.

Additionally - having code blocks call other code blocks is also very natural. A useful function of code blocks is to break the task down into smaller manageable tasks. Bonus points if this code is designed to be re-used.

BR