Problem uploading tag values, fault on system.

Hello,

Last Friday I uploaded the program on the Rslogix 5000 and saved it, when I saved it, it asked me to save the tag values and I clicked yes. I edited the program offline since I need to create produce and consume tags. When I downloaded the program, after the edits, all the tag values (set points) changed and it caused a problem for production and they couldn't run since they didn't have the recipes. What could have happened? I created a backup before doing the edits and downloaded that program and it still came up without my previous tag values. I still need to edit the program but don't want to run in to those problems. Any advice?

What version of 5000? Is there code in the processor that resets tag values when the PLC is restarted? Any kind of nonvolatile memory being loaded?

What tags or set points tags exactly? Current step times/step numbers?

The likely scenario is that the program you uploaded on Friday recorded certain recipe, step numbers/timers, etc. for the sequence that was running AT THE CURRENT TIME last Friday.

Now if you come back a week later, and download this same program back into the PLC with a few small edits, whatever current processes, steps or tag values that were running will now be changed back to the state they were in when you did the upload LAST FRIDAY. See the problem here?

One of the things I learned very early in my PLC career (the hard way I might add) is that it is always better to work online with the PLC if possible. Failing this, what I will do is take an upload of the PLC program, then work on the program offline. When I am ready to implement the changes to the system, I will then go back on-site and take ANOTHER upload of the program with all current tag values, then I will copy/paste the changes from the program I've been working on offline into the 'fresh' upload before downloading to the PLC. This way there is minimal chance of encountering the issues above.

I would always get the client to put the system or process into a 'paused' or 'resting' state while you do the fresh upload, copy the changes in, then download. I would never do it while they are in the middle of a normal process or production step.

Ok, this is the second similar case I've come across this week. It pays to learn the auxiliary tools available to you...

If you are working with systems where it is critical to preserve the current tag data to within a relatively short period of performing a download then you should use the Data Preserve Download Tool. It saves the tag data out to a CSV file and once the project download is complete it then downloads the tag data back into the controller. You use this tool just before performing a download so the tag data is as current as possible...

54946 - RSLogix 5000 Data Preserve Download Tool
Access Level: Everyone

Regards,
George