FC's FB's and other step7

hello,



please correct me,



1.OB for example calls FB which calls FC, and DB is made for variables used by all or any FB's FC's???



2.and SFB and SFC are biult in blcoks that you can use in your application??



3.and what is exactly the varaible table for if you have DB's??



4.where can i get the list of syntax of all functions such as: s5T#2s



thank you

1) In principle yes, although you can also call FCs directly from OB1. DBs can either be "Global" - available for general access, or "Instance", belonging to a specific FB. However, these "Instance DBs" can also be accessed by other FBs / FCs (preferably read only though!).

2) Yes.

3) The Variable Tables (VATs) are only avaliable offline and are primarily used for testing. With them you can observe the state of all memory variables, not just DBs.

4) You can find this at the Siemens support web-site. Unfortunately, I'm not in the office at present, so I don't have the address handy. If nobody else has posted it before I'm back in the office tomorrow, I'll post it then.

Hope I've covered what you wanted, if not come back and post the questions again, perhaps slightly differently phrased.

Hello,

To follow RMA's well-rounded answer, here is a link to Siemens' support website. Use the Search utility to look for documents. I recommend "Programming with step 7", "Ladder with Step 7", "Standard and system functions" to get direct answers to your original questions.
http://www4.ad.siemens.de/-snm-0135030360-1078737597-0000010179-0000000017-1079359750-enm-WW/llisapi.dll?func=cslib.csinfo&changelang=true&aktprim=0&siteid=cseus&lang=en

By the way, if you are working with a computer that has Step 7 installed, those documents and others have been made available to you already (Start--> Programs-->Simatic-->Documentation).

Hope this helps,
Daniel Chartier

Press F1 on the command you have problem in the software will try to find a propper answer