Siemens Step 7 Help, Noobie here

gerberz said:

Hello everyone I am new to Siemens Step 7 and having some issues


I was going to add the a FC to OB1 (Network 28 In Image 1)
But it was asking for this “RET_VAL:=”

I found that I was intending to use a temp bit but ended up making a interface return bit. (see Image 2 for reference)

The issue I am having is I seem to not be able to delete the return bit. I will be using the temp bit instead.
How do I delete this?


Also a second question.

What are the purpose of these “NOP 0” after the “Call FC ##” in OB1?
(Image 1 for Example)



Thanks all!

I'm the only Controls Engineer on my shift. I have 4 years experience with AB and RSlogix but Im new to Siemens. SOO probably gonna be here a lot!

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gerberz said:

Also a second question.

What are the purpose of these “NOP 0” after the “Call FC ##” in OB1?
(Image 1 for Example)

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mk42 said:

Try making the return datatype VOID, or something therebouts.

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RVaughan said:

As mk42 suggests, you should be able change the Ret_val data type back to the default to make it no longer required (black instead of red).
Create a new FC and see what is in its Return section, make your data type match.

NOP is an instruction for the compiler to show instructions in Ladder language. It effectively does nothing during the cycle.

If you're in doubt about an instruction, place the cursor on it and press F1. Every Siemens instruction has its own help file, including System blocks and all the blocks in the standard library.

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gerberz said:

We use NOP in Rslogix also but i dont get why they would use it after each FC call

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gerberz said:

This made it so was not require but was still not able to delete it

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L D[AR2 said:

Modify your FC so return value is type VOID
Save your FC

Delete the call to your FC in OB1
Save OB1
Insert the call to your FC again
save OB1

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