Variable Range in PLC program

[iannicholson]

I'm using a range of P-variables to store positions (P800..899). I can issue the following online command to zero out all of the P-variables in the range:

 

P800..899=0

 

This doesn't seem to work in PLC or motion programs, however (it gives a syntax error in PEWIN32Pro). I have tried the following instead:

 

CMD"P800..899=0"

 

This does not give a syntax error, but I'm not confident that it is having the intended effect (I have a customer running the code, so I don't have direct access to PMAC from my shop currently). Is this valid?

 

I assume that I could write a While loop and incrementally write 0 to each variable, but this seems inefficient.

 

What is the recommended method to write a single value to a large range of variables when in a PLC or motion program?

[steve.milici]

This is valid. You will need a one-time while loop to force the execution at that point as in the following:

 

Cmd”P800..899=0”

P900=1

While(P900=1)

P900=0

Endwhile

 

A Cmd”” is not executed until the end of this PLC’s current scan. The while loop acts as a “current scan”.

[bradp]

I would change this to be

 

Cmd”P800..899=0”

P899=1

While(P899=1)

P899=0

Endwhile

[steve.milici]

Save a P-variable, save some electrons and promote global power reduction. Good work.

[iannicholson]

Great suggestion. And sarcasm ;)

 

I was aware that some functions don't process until the next scan of the PLC, but I wasn't really sure which ones they were. This explains what might be going on here.