Passing a large INOUT to FC in S7-300

[MorphuisOGrady]

No. DB just contains 50 members of type udt.no arrays used

 

[L D[AR2P#0.0]]

Why did you not use the UDT as a declaration in the temp area of the FC ?

 

[KalleOlsen]

Here is an calling example of an AI block with a channel driver from an older PCS7 library from Siemens. The AI and the channel driver blocks are FB's, each instance has it's own DB (DI).
When I make the AI-blocks I normally integrate the channel driver.

Kalle

 

[MorphuisOGrady]

As opposed to cutting and pasting all the members into the local area?

Is it better to do this?

 

[L D[AR2P#0.0]]

Yes, once you have declared a UDT the idea is to use it when ever you need to refer to the data structure.

 

[metwally.mustafa]

hi L D[AR2,P#0.0] i admire this symbolic name so much it's really fantastic, I will be happy if you describe you shared program(inout) in details as there are some instruction which is unknown to me for instance
i know the meaning of the instruction SLD 3( shift lift double ) but i can not understand the program algorithm ,nevertheless the program is so good ragardless the degree of difficulty of the program ,honestly, i found dealing with pionter is difficult enough to understand , but if you had described the details of pointers , it would be a great job
or doyou have a short pdf file about pionters or indirect addressing for beginners ?

 

[L D[AR2P#0.0]]

Start another thread..

 

[MorphuisOGrady]

Hi LD,

Thanks for your input. I ll change the fc then. Is there anything else? Will this be ok?

 

[L D[AR2P#0.0]]

Please comment!!! If its bad please tell me, I havent done much S7.

Copying the DB to the temp area, performing the processing and copying it back again is a valid methodology. As you have already said, the temp area will have to accomodate your UDT, Eventually if the temp area gets too big the CPU will fault.

You are addressing the temp area absolutely - this may bite someone later if they decide to add another temp variable (outside the scope of your UDT) at the start of the temp area - the load/transfers will not copy all of the UDT data.

 

[MorphuisOGrady]

Yes that's true. But it's not a bad way to do it then?

That's great. Thanks for your help

 

[L D[AR2P#0.0]]

Your UDT appears to be 102 bytes long, not 100
There are various DBW references in your copy to/from temp/DB - I presume these are typos?

 

[L D[AR2P#0.0]]

Here's your FC recoded as an FB with my FC99 setting up the instance DB according to the AI number. For brevity, I've used a few M flags to pass the parameters to the FB. To make the FB entirely data driven, you could add the PIW address to the UDT. I've replaced your one second flasher with M100.0

 

[MorphuisOGrady]

Your UDT appears to be 102 bytes long, not 100
There are various DBW references in your copy to/from temp/DB - I presume these are typos?

Yes these are typos. I haven't tested it yet. Didn't spend too much time on it yet until I know its OK to do this.

 

[MorphuisOGrady]

Here's your FC recoded as an FB with my FC99 setting up the instance DB according to the AI number. For brevity, I've used a few M flags to pass the parameters to the FB. To make the FB entirely data driven, you could add the PIW address to the UDT. I've replaced your one second flasher with M100.0

Great. Thanks very much for this. I'd still prefer to use my method if its not going to be a problem. Keeps all my control modules consistent.