AB - Unscheduled Programs / Phases

Let me start by asking my question and then explaining it: In RSLogix 5000, are the logic and devices written within Tasks that reside in the “Unscheduled Programs / Phases” section of the controller completely ignored or are we subject to “Double Coil” issues and similar problems when duplicate logic exists?

I’m working on a program where the upcoming modifications will be done in a couple of phases and I’m wanting to pre-program for the second phase but keep it inactive by way placing future Tasks in the “Unscheduled Programs / Phases” section of the controller. The way I have it planned, one particular Task is used in the first phase and will be replaced by an expanded version upon implementation of the second phase. Because I want to “finish” the code rather than cut & paste and modify during the future implementation, I would like to have duplicate coils other counting logic in both Tasks. Obviously I don’t want the processor confused by double-coils, etc.

Can anyone tell me how the processor truly handles Tasks stored in the Unscheduled Programs section?

Steve

I don't know much detail of how it works, probably a conversation with Rockwell Tech support, but according to the help file the program won't run at all. I've done similar with what you are looking at doing and have not had issues that I was aware of. Keeping your new logic unscheduled and re-scheduling at a later date should be seamless less the actual logic changes.

That's excellent. I believe I'll give it a try.

Programs within a project that are not scheduled by any task; they do not execute. Programs may be left unscheduled until needed (to add futute functionality or for troubleshooting).

Out of my Logix5000 System Glossary

To be clear, there is a hierachy in the tree:
Tasks > Programs or Equipment Phases > Routines.

Only Programs can be moved to the Unscheduled Programs or Phases (where the logic wil not be executed).

If you are just affecting a Routine within a program, then you can simply remove or block the JSR to that routine and the logic will not execute. This can be handy when implementing new changes because you can import a new version of Routine_1 as Routine_1A and simply toggle a bit to JSR to the new or old version.

Steve,

I do that all the time. I keep a program called TestBed on many PLCs. The program is usually unscheduled and it does not execute. If it does not execute it does not modify anything anywhere in memory. When I want to test something I add the code I need, schedule TestBed in some existing task (A task can have multiple programs scheduled in it) and when I'm done testing I unschedule TestBed.