RSLogix: How to return/exit a AOI part way through function

jatz76 · Mar 5, 2012

Hi,
I'm converting some code from Unity DFB (in structured text) to RSLogix AOI (in structured text). The Unity code uses the RETURN instruction to exit the DFB at certain points. Is there an equivalent in RSLogix?
Return definition in Unity:
In a DFB, a RETURN instruction forces the return to the program which called the DFB. The rest of the DFB section containing the RETURN instruction is not executed. The next sections of the DFB are not executed.
Cheers,
Jacek

daba · Mar 5, 2012

In the logic for the AOI, put a conditional rung to execute a TND instruction. See pic from instruction help...

In ST language, it's TND();

jatz76 · Mar 5, 2012

Thanks heaps daba. I'm pretty experienced in logix but have never had to do this. I find the Logix Help useless unless you specifically know what to look for.
Cheers,
Jacek

daba · Mar 6, 2012

jatz76 said:
Thanks heaps daba. I'm pretty experienced in logix but have never had to do this. I find the Logix Help useless unless you specifically know what to look for.
Cheers,
Jacek

I find the help extremely good.

If you want help on an instruction in the code, just highlight the instruction name and hit F1.

Or, goto Help, Instruction Help, and click on "Alphebetical List" (about the second line), then choose the first letter of the instruction. You'll see how it works.

jatz76 · Mar 6, 2012

It is ok if you know the name of the instruction in the first place. Searching for Return or Exit etc doesn't get you to TND. Guess they could have a few extra key words that help describe the instruction.
Anyway, thanks for your help.

daba · Mar 6, 2012

jatz76 said:
It is ok if you know the name of the instruction in the first place. Searching for Return or Exit etc doesn't get you to TND.

Good call, and point taken. Because I know the machines, and their instruction sets quite well, it's pretty easy for me to find help. For instance I might "guess" an instruction does what I want, then I go check the help on it. I can see that I approach the help from a different angle....

RSLogix: How to return/exit a AOI part way through function

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