First Pass implementation on RSLogix 5000

How can we implement the First Pass S:1/15 of RSlogix 500 into the S:FS (system tag) of the RSLogix 5000? Kind of new on this one. Thanks

The S:FS bit works the same in Logix the way the S:1/15 First Pass bit works in SLC-500. It is only true the first program scan after the controller transitions to RUN mode, either from powerup, keyswitch, or RSLogix control.

S:FS is one of the few "pre-defined status tags" in Logix; Everything else is accessed with GSV instructions.

I have only used the S:FS bit in the Continuous Task of a Logix controller; I'm not sure if it works the same for the first execution of a program in a Periodic Task.

Science Project, anyone ?

Just looked through several programs, including one done by the boys in Mequon, and found several instances of it being used in Periodic tasks.

Each program has its own S:FS bit. Routines in each program do not appear to have individual S:FS bits, but multiple programs under each task do appear to have their own S:FS bits.

There is also a write up on it at the AB knowledge base under technote 34980.

thanks, Alaric ... I had posted a preliminary experiment - but then deleted it after I decided to dig deeper ... the link you provided will help ...

Ron Beaufort said:

thanks, Alaric ... I had posted a preliminary experiment - but then deleted it after I decided to dig deeper ... the link you provided will help ...

Click to expand...

I wondered what happened to your post.

I thought it was a very good demonstration of how it doesn't matter whether the program runs right away, or several seconds later, how the S:FS bit will still work for it.


edit: In the event you can't access the KB technote, I have attached the file from the KB. It has a good example in it. And, if you are astute, it will show you what can be a pitfall if you don't plan for it. (I'll bet Ron could dream up a demonstration of the pitfall for one of his classes that would turn a few faces pale)

I think that I got the basic "rules" correct ... but some of the language that I used MIGHT have been a little bit ambiguous ... I'll try to rewrite it tomorrow and then repost the results ...