Sti in RSLogix

OK Since I am working on a SLC 5/01 I don't have STI available.
Now LAD 5 comes out of the box named STI_INT.

Can I rename LAD 5 and use it like any other subroutine file?
I think I can.
Would this be bad practice?
I appreciate any and all of your oppinions.
Thanks

I think that only the Micrologix-1000 has routine five pre-named as STI_INT. Click on controller properties in your project tree and make sure your processor is set correctly.

The answer to your question however is yes. You can rename it and use it normally.

I think that only the Micrologix-1000 has routine five pre-named as STI_INT.

Click to expand...

You're right.
That's what I get for trying to work from an existing Ladder file.
I had already changed the processor Type: in Controller properties, but that didn't rename the files.
Thank-you

Greetings gbradley,



first let me see if I’ve got this right ... please correct me if I’m wrong ...



you have an existing program which was originally written for something like a MicroLogix1000 ... this program made use of Ladder File #5 as an STI ...



now you want to adapt that program to run in an SLC-5/01 ... the SLC-5/01 doesn’t support the STI feature ...



so you want to know if you can use the rungs in Ladder File #5 by simply “calling” that file with a JSR ...



if all of that is correct, then as my distinguished colleague Alaric says, the simple answer is “yes” ...



but going just a little bit deeper ...



I just have one question ... why were those particular rungs programmed in an STI in the first place? ... if the answer is “for no particular reason” then you’re probably ok ... but ... suppose that the answer is “those rungs are required to execute at a highly predictable time-critical rate” ... then you might (just MIGHT!) be painting yourself into a corner ... keep in mind that simply calling Ladder File #5 with a JSR will not duplicate the “time-critical” execution of an STI ...



obviously a lot of this has to do with your particular application (scan time, etc.) ... and also, I have a tendency to “overkill” even the simplest problems ... sorry if I’m needlessly complicating this, but I’m just wondering why was the STI used in the first place? ... and if using an STI is the only way to make the program work correctly, then maybe an SLC-5/01 is not the way to go ...



or maybe (probably?) I’m just misunderstanding your question? ...

Ron, I think he was just refering to it coming "out of the box" that way, I dont know that there was actually any existing code in Lad 5. Maybe gbradley will clarify.


Gbradley, I wonder why you are "stepping backwards" by going from an app written for the ML1000 to the SLC5/01 when the 5/01 is a lot more expensive than a ML1000, unless more IO is needed. But then why not use a ML1200? Its a lot less money as well.

also, I have a tendency to “overkill” even the simplest problems

Click to expand...

Me too. Big time. Reminds me of a recent emberassment when I was training the maintenace guys on a program I wrote and one asked me "why didn't you just...."

No The STI rung did not have any ladder rungs in it.
I just started my Ladder by modifying a file that was originally written for the ML1000.
There was no STI code ever.
I have a SLC 5/01 that I am writing brand new ladder files for, and I thought that I would start by using an existing ladder file that I had previously written for a ML 1000.
When I said out of the box that was because I had not created or named the LAD 5 - STI_INT file.
I see now that if I start from scratch and pick the correct processor, I only get LAD 2 and I can add ladders from there.


Speaking of STI...

Ron maybe you can explain this.
OK I know I can't do this with a 5/01, but let's say that I have a ML100 and I want to use the STI.
Well the rungs that I want to scan are put into that Lad 5
So I have to put 5 into S:31 so that the processor knows which is the STI file number.
How com I can't see that setting in the structured format?
I have to switch to Decimal or binary view of the S bits.

In the ML1000 the STI is locked to Lad 5. Changing the value in S:31 doesn't seem to have any effect. I have a ML1K sittng on my desk right now. I put

XIO O:0/11 OTE O:0/11

as the sole rung in Lad 5 and set the STI setpoint in S:30 at 200. Then I put

XIO O:0/10 OTE O:0/10

as the sole rung in Lad 11 and changed S:31 to 11.

The only output flashing on/off at two seconds is O/11, meaning that no matter what is in S:31, Lad 5 is the default STI in the ML1K. I wonder why they did that?

Interesting...
So this means that If I was working on a Micrologix 1000, and I write a conditional subroutine and put in Lad 5, it may still get scanned even if I don't explicitly call for it.

Currently I am working on a SLC5/01 so I don't think LAD 5 has any significant importance here.

gbradley said:

Interesting...
So this means that If I was working on a Micrologix 1000, and I write a conditional subroutine and put in Lad 5, it may still get scanned even if I don't explicitly call for it.

Click to expand...

As long as S:30 is set to 0, the STI is inactive. But if you put anything else in S:30, then it becomes an active STI. Like I said, I wonder why they did that, especially since the ML1K is limited to ladders 2 - 15. You could unconditionally execute the STD instruction in Lad 2 to keep an STI from occuring if something accidentally gets put in S:30 if you must use the routine.

Currently I am working on a SLC5/01 so I don't think LAD 5 has any significant importance here.

Click to expand...

Correct. In SLC5/03/04/05 you can set which routine is the STI.

I also noticed that the ML1K would not let me toggle the S:2/1 bit (STI enable).