OB1 cycle theory question.

Hello everyone,

Looking at relatively huge programs that were created by machines' manufacturers, I noticed that only little of FC and FB had put in OB1 or in the others OBs (if they are existing).

My observation: e,g., 2 of 42 FBs were put in OB1. And 9 of 64 FCs were put in OB1. Others OBs are empty.

With a view to all textbooks on Step7 that keep telling that "to get your program executable you must put FC or FB in OB1. Otherwise your program won't be executed."

These textbooks statements are correct, because I and probably everyone ever tested (forgot to put)  that. FBs or FCs which are out of OB, they aren't being executed.

A question: My observation and textbooks statements are to be incompaible. Aren't they?

Any comments.

Msorich

 Dear Msorich, you are correct in that for your the operating system to execute your program blocks it must be called from OB1. 

1. WHAT IS OB 1.

OB 1 is the interface between the user program and the operating system. But don't forget this that it is very possible to call blocks within blocks. For example, i have FC 1, FC 2 and FC 3 in my program respectively.  it is possible for me to call FC2 and FC3 directly from FC1 provided i had called FC1 from OB1. You can do this if you have some conditions to be met before that particular block can be processed.

Success.

Hope this is helpful......

Msorich

Hello everyone,

Looking at relatively huge programs that were created by machines' manufacturers, I noticed that only little of FC and FB had put in OB1 or in the others OBs (if they are existing).

My observation: e,g., 2 of 42 FBs were put in OB1. And 9 of 64 FCs were put in OB1. Others OBs are empty.

With a view to all textbooks on Step7 that keep telling that "to get your program executable you must put FC or FB in OB1. Otherwise your program won't be executed."

These textbooks statements are correct, because I and probably everyone ever tested (forgot to put)  that. FBs or FCs which are out of OB, they aren't being executed.

A question: My observation and textbooks statements are to be incompaible. Aren't they?

Any comments.

Msorich

Hello.

Msorich

Hello everyone,

Looking at relatively huge programs that were created by machines' manufacturers, I noticed that only little of FC and FB had put in OB1 or in the others OBs (if they are existing).

My observation: e,g., 2 of 42 FBs were put in OB1. And 9 of 64 FCs were put in OB1. Others OBs are empty.

With a view to all textbooks on Step7 that keep telling that "to get your program executable you must put FC or FB in OB1. Otherwise your program won't be executed."

These textbooks statements are correct, because I and probably everyone ever tested (forgot to put)  that. FBs or FCs which are out of OB, they aren't being executed.

A question: My observation and textbooks statements are to be incompaible. Aren't they?

Any comments.

Msorich

There are information that can get lost in human-to-human explaining between languages but also technical to non-technical-writers. Keep this is mind.

The code blocks (FB / FC) does not need to have direct contact with an OB. It can be through a call structure also. Think again of that statistics you speak of - which of those code blocks are called indirectly by an OB?

Example:  

OB1  ->  FC1  ->  FB1, DB1
              ->  FB2, DB2
              ->  FC10       ->   FB10, DB10

Another scenario ->

At times we have code in the program to (1) cover all scenarios (2) testing algorithms.

The persons who commissions the machine is not the original designer. Those codes are there for them to swap out code pieces to ease their job to get the system running and customize where needed.

If this does not help you, please specify where I misunderstood you or try your German some more.

Haben sie einen guten tag.

Hello guys!

So to speak, to finally dispel my doubts tell me please, what does mean marked with cross signs in the Program Structure graph. Find a snap at the attachment.

Msorich

Msorich

Hello guys!

So to speak, to finally dispel my doubts tell me please, what does mean marked with cross signs in the Program Structure graph. Find a snap at the attachment.

Msorich

Touché!

It has been a long time not using Step7 Classic - but YES that looks to confirm your suspicions. My  reasoning still stands.

Perhaps one more - the PLC was used for another project before; and not cleared before being re-used. Possibly some functionality was reduced but left in place for the case that the "client" changes his mind.

What do you think is more likely?

Very possibly you can upload a backup and delete the blocks not needed. The compile action will tell you if there is problems.

Msorich

Hello guys!

So to speak, to finally dispel my doubts tell me please, what does mean marked with cross signs in the Program Structure graph. Find a snap at the attachment.

Msorich

 Hello Msorich, to answer your question, the blocked marked with an X are non called blocks, if you look closely at the call hierarchy, they are not under an OB tree, remember that OBs are the interface between the user program an CPU's OS, if they are not called under an OB, they are not executed.

Hope this helps.

Regards.

@Rescobedo, I  have certainly noticed that some Blocks are out of OB1 and marked with a cross.

So, I asked about them. Thank you! Just have a 'bad' habit. Everything keep cheсking.

@#dp, The PLC wasn't used before. It was brand new and virgin hardware. My idea is pretty close to yours and sounds like: 'a template project was uploaded to the PLC where was adapted to concrete configuration while commissioning of the machine/line. So some  blocks turmed out to be beyond the OB1.'

P.S. as concerned Step7 Classic, I already stated somewhere, that we are still permitted to use TIA. We have that installed onto 'laboratory' laptop.

Msorich

 Hello there,

I prefer to follow that proverb: 'If it ain't broke, don't fix it'.

Anyway you all extended my knowledge with pure theoretical advices, cautions and so forth.

FYI: Most of blocks are called indirectly, some blocks sit at OB1 and some aren't being called at all, so to speak unused ones.

@fritz, that's cool setup to use loop for blocks calling. It seems my OEM doesn't do such cr*p. Just leaves regularly lots of rubbish behind.

Thank you!

Msorich