PLC5 Buffer Overflow. Too Many Edits

So I was making some program changes to a PLC5/80 E-2000/Files Extended Rev F controller the other day and I got knocked offline with the following message. My memory usage is 55067 and free memory is 47333.

Buffer Overflow. Too Many Edits.

That's it. No error code no nothing. I was forced to do an Upload and Merge to get back online. I have never had this happen before but it hit me about a dozen times that day. Has anyone else had this issue? What is the cause?

I have contacted tech support and they are stumped. they actually have no record of this message anywhere and they are referring it to their engineers to get more info. They think it may be an issue of memory fragmentation and I may need to download the program again but have not committed to this answer as of yet. I will update with more info if it becomes available.

Kraken Fan #69

I do not remember the error code, but I have been kicked off line when 3 people were on the same PLC doing edits.

how many rungs were you editing?
by that i mean how many differengs were in edit mode when this happened?

is it always a good practice to save your work every 5 rung edits or so to help prevent this.

regards,
james

I had copied 7 rungs from an offline program and pasted them into the online program
and was accepting them one at a time. later it would do it if I edited one rung to add a branch around an alarm trigger to test the alarming on the HMI. So I guess it varied. I was the only person online.

Kraken Fan #69

I know that it's true of Modicon Quantum processors (because I've seen it recently), and I think it's also true of PLC5s, that making a large number of online changes can fragment memory usage in much the same way that a hard disk drive can become fragmented.

With the Modicon, you should run an optimization of your program and then download it to free up memory for compiling online changes. With the PLC5, if this is a problem, then you may simply need to do a download. I know that with the Modicon, simply downloading without optimizing has allowed online changes again. Unfortunately, you have to stop the processor, either way.

Rockwell sent the issue to thier engineers and they say there is an Edit Transaction Buffer (don't quote me on these names) that keeps track of online changes and something in there must have become corrupted. They suggest saving the file as a ProgramName.PC5 (which will basically be a text file) and powering down, removing the battery wait 2 min (give or take) and import the file back into the controller. This should clear it all out and fix the issue.

Kraken Fan #69

Sounds like a plan. It will nudge you to check your battery and give you a fresh download, if nothing else, huh?