SLC500: odd problem

I have run into a problem with a SLC500 and I would appreciate any help that might give me some insight into why this problem occurred. Also, bear with me since I am still rather inexperienced with the product having only recently started working at my company.

Background information:
The PLC is wired into our network and we are able to ping it. the system is also running in remote run mode. I went into the program and was able to go online this morning without any problems. The location is active on RSLinx as well.

This afternoon, my colleague mentioned that he was unable to go online with it, but was able to ping the device and it was still running. Following the normal "who's online" path, matched the file to the plc and tried to go online, it returned a "no matching file found".

We have made no changes to the file and the plc memory has plenty of space still available. We were able to upload a file and are using that for now, but losing hundreds of descriptive tags isn't exactly the best thing to happen. We compared live to "problem" files and found no inconsistencies, and browser location matches too.

Has anyone else run into this problem before? And if so, how were you able to rectify it?

Welcome to the forum.

Before uploading make a backup of copy of the PLC program. Then when RSLogix indicates that no matching file is found click the browse button and browse to the folder where the PLC program is kept. Then click the Upload Use File button and RSLoigx500 will then use the existing comments from the existing file. Hopefully you haven't saved over the original file. If you have then RSLogix keeps a few backups so you will need to revert to one of those that still has the comments in it.