Question about calling FC's in S7

[uptown47]

Hi all

I've translated an S5 program into S7 but unfortunately it doesn't work.

I've even used the S5 converter to check my conversion and it seems fine.

Within the S5 there are several calls to the same block, FC 83, which is a S5-S7 Block 16bit Multiplier.

My question is this...

Could it cause a problem calling this block several times from within the one block and sending different parameters to it?

Or is it perfectly acceptable to call these blocks as many times as you want and just send different values each time??

If it was an FB I would put different Instance DB's with every call but with it being an FC I don't have that option...

Can anyone clarify this for me

Many thanks in advance

 

[PeterW]

An FC can be called as many times as you want, one after the other if you want.

The rules with an FC, internally is simply, if the parameter is an IN, then do not write to it in the block, if its an OUT, then ensure that you condition it in the block prior to using it.

If you need to update an IN or remember an OUT, then it has to be IN_OUT.

Providing the above is adhered to you should be fine.

Regarding the data passed in and out, ensure the same addresses are not being used which can cause errors.

 

[uptown47]

Thanks for clearing that up for me Peter.


Much appreciated

 

[L D[AR2P#0.0]]

Can you be more specific about what is not working ?

(e.g. I've just built a nuclear power station and it's not working - can anyone help)

 

[uptown47]

Simon

I've expanded on my 'brief' statement

Please read the full details here:

http://www.plctalk.net/qanda/showthread.php?t=39547

Many thanks