Maintaining a spare Logix L81E module's program

[glennz]

Scenario: client has a non-redundant L81E controller with one Ethernet connected remote chassis. Several spare slots are available. By contract, they were also supplied a spare L81E that sits on the shelf in case the production module dies. We are responsible for maintaining a current program in that spare, and that situation arose this week when I was on-site making edits on the production controller.

I had no spare chassis with me. I was about to plug the spare into an open slot in the remote chassis so I could download the revised program via USB, but I stopped myself over concern that the production program might fault due to a second nearly identical program causing conflict over ownership of output modules, even if left in Program mode.

What to do? Are my concerns unfounded? Suggestions on how to take care of this? I have remote access to the system so I don't necessarily need to make another road trip for this.

 

[Operaghost]

Taking ownership shouldn't happen, but it is possible if there is a brief loss of communications between the CPU and the I/O module. When communications are reestablished, both CPUs will try to take ownership. Whichever one gets there first would become the owner. So it shouldn't happen, but it certainly could.

I usually suggest the SD Card for this. Whenever they need to swap processors, they also pull the SD card from the failed CPU and plug that in to the new CPU. I have the SD card configured so it will load during powerup if there is no program loaded in the CPU. The downside is that the SD card would need to be updated whenever their are changes that must be saved. And that requires switching the CPU to Program mode. That just isn't always an option.

I'm not sure if AssetCentre can load a program into the controller. I know it can upload, but I'm not familiar enough with it to know if it can download too. Maybe someone knows or has a better solution.

OG

 

[alan_505]

The processor needs to be in the slot assigned to it in the program so if it is in slot 0 you will need to put it in slot 0 to be able to download the program to it.

That is what I have found.