Undef started showing for part of my tags

I have historical logging configured for 24 tags. They are divided up to two groups and each use a different topic on the same IO Server. The only difference is the poll rate for Topic A is 10000 MS and Topic B is 1000 MS. I have a script exporting the historical data every hour. This has been working fine for several days then this morning the group A tags started showing as undefined in the exported files (see attached). Nothing was changed on the flexy or PLC and all the tags still have values under Tags:Values. I was wondering what caused this to happen and how to fix and prevent it from happening again.


Can you provide a backup with support files of the affected unit?

I will review this information, and see where the problem might be.

I think we may have figured it out based on my limited flexy knowledge. See if this makes sense. The tags were set to logging deadband only and the machine had not been ran in several days. There is another group of tags that are logged on deadband and interval. I’m thinking that maybe the history file (ircall.bin I think) got full and the records for the tags in question were dumped since they were the oldest records. This caused them to show up as undefined in the export. I have added an interval to a couple of tags and they are working.

I have attached a backup with support files in case the above is does not make sense.



Hi Scott,

Yes, when the log is full it will remove the oldest data first so this is probably what you were running into.