Help to understand EN/ENO mechanism

 I think ENO is an indication that block has been executed error free, i.e. ADD, SUB library blocks from Siemens, I.e overflow.

there is also another type of error, i.e. if you pass in a value into the block for processing, and you might want to write some code to check if it is a sensible value, i.e. within minimum range and maximum range, if outside the range you can choose to write some code to limit the value to minimum or maximum range or substitute a default fallback value, and additionally flag up an error, this error will be user programmed instead of ENO. 

Elux_Peter

Hi

I'm trying to understand when the output "ENO" goes high on a block/instruction. When reading the help text it says that if the processing of the instruction is okay the ENO goes high, does this mean that all of the instruction also is executed when ENO goes high?

When programing I sometime use the ENO as a indication that the instruction is done and that I can use that result in anotherinstruction (see attach picture), could that cause problems?

Thanks for the help
Peter

But Surprise!

I wanted to verify this behavior on an S7-1200. In this SAME project I only changed CPU. Code was the same (except instruction SAVE).

Over this CPU, ENO was enabled spite of I dindt use "SAVE" instruction!!

Why?? I cant understand why S7-1200 works in different way that 300.

Anyone has an explanation, please?

Thanks

Hello

Thanks for your answer.

I have tried to review F1-help but there are 599 entries when you look for "ENO" info and none of them talks about differences between 300 and 1200 specifyly..

Could you recommend me any help more specific or any pdf manual or similar?.

Thank you again