Stumped By B3:x OTE

Infantry Dave · Feb 6, 2015

Good Morning Everybody,
I'm using RSLogix500 and programming a Micrologix 1100.
I define all my outputs using B3 data file and reference those bits as outputs through out the program.

However, when I provide an OTE for these bits, (most are in subroutines, JSR'd from the main file, with no conditions for the jump), the program will not write a 1 to that slot and subsequently no output when the conditions are true.

I currently have no latching or unlatching function related to these bits, and checked the code line by line.

Am I missing a property or setting some where. Also, some B3 bits do work.

I'm stumped.

MATT116 · Feb 6, 2015

Infantry Dave said:
Good Morning Everybody,
I'm using RSLogix500 and programming a Micrologix 1100.
I define all my outputs using B3 data file and reference those bits as outputs through out the program.

However, when I provide an OTE for these bits, (most are in subroutines, JSR'd from the main file, with no conditions for the jump), the program will not write a 1 to that slot and subsequently no output when the conditions are true.

I currently have no latching or unlatching function related to these bits, and checked the code line by line.

Am I missing a property or setting some where. Also, some B3 bits do work.

I'm stumped.

This is probably your problem
reference those bits as outputs through out the program.
You should only have one OTE per bit through out your program.
The last instance in the scan will "win"

the_msp · Feb 6, 2015

If you want B3:1 to turn on output 1, but also later in the program have a separate function turn on output 1, then have B3:2 turn on the same one.

At the end of the program, have the outputs addressed as an OTE, called by XIO B3:1 OR B3:2.

Search the forum for "double coil syndrome"

MATT116 · Feb 6, 2015

the_msp got it "double coil syndrome"

Infantry Dave · Feb 6, 2015

Thanks guys,

I'll take in your advice. I've gotten away with this logic before, but maybe I didn't have double coil syndrome going on in those programs.

Patrick, I actually XIO those bits at the beginning of the program. Maybe bad form.

Thanks again

the_msp · Feb 6, 2015

It's personal preference. I organise my code that is all contained in one routine (e.g. processors that don't have sub routines) as:

Inputs at the top (Input map real IO to flags, in AB B3:x)
Process in the middle (sequencers etc, input flags request output flags here)
Output at end (Here output flags trigger real IO outputs)

I find it easier to follow. Most PLC's scan top to bottom, left to right. If you were doing time critical applications, in your method it would take 1 extra scan time to complete. Negligible in most cases.

Stumped By B3:x OTE

Infantry Dave

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MATT116

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the_msp

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MATT116

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Infantry Dave

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the_msp

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