Please can you advise on best practice or on how you view the following:-

In the attached screenshot I have two Function Blocks written in STL. Both blocks have Inputs and Outputs assigned. My question is how best to link the output of one into an input of the other. This can be simple boolean outputs or even real values.

This is my first venture into the S7-1200 and it made sense to me to reference the required output from the associated Data Block as in the screen shot. However is it better to assign a local temp variable from the output of a FB and then feed this temp tag into the input of the other FB?

E.g. In the screenshot, output 'Boom_Raise' from FB 'Boom Control' is fed into the input of FB 'Basic Proportional Valve Control' 'Joy_A' as "Boom Control_DB".Boom_Raise.

It just looks strange to leave the outputs unconnected?

I am very interested in your replies.

 Hi Hdhosseini,

Thank you for clearing this up for me, I'm glad I was on the right track. I had never looked at CFC before, I think I will stick to the method you suggested below. I have previous experience of a Beckhoff system and although you could interconnect everything it would sometimes turn into a mess. The Data Block system makes sense to me for now.

If I am writing an SCL FB should I provide an "input" for everything I wish to work with or is it OK to reference the data in the SCL code directly? I'm guessing that referencing a DB directly in the SCL code does not make a very portable or reusable FB.

hdhosseini

Hello,

In CFC is possible to interconnect variables of  blocks graphically. For LAD, I suggest calling each block in an individual network.Leave the outputs of FB alone and you don't need to use temp variables to copy the
 content. In FBs, all  inputs/outputs/static/inouts are saved in global IDBs and they are valid in your entire program, you use them like "DB_NUMBER"."Name_of_parameter".It is normal to use outputs of an FB that is processed earlier as inputs of FBs in next networks.


I hope this helps,
hdhosseini

Hello again,

I suggest reading the following thread on a similar discussion.Despite the fact that it is about calling FBs in SCL for STEP 7 classic, but I think the ideas are still applicable in TIA Portal:

How to call a Function or Function block in an Organization block in SCL.

I hope this helps,

hdhosseini