What is purpose of log data check box when creating tags?

[unclebump]

I have an .scf file with over 4000 tags in it. Only 100 of them are checked to log data. I verified this by reading the tag properties for all tags and counting only the ones that had logging turned on. When I start the tag engine and create a historical data file in MAX, I am seeing 4000 traces available before I even try writing new data to the tags. The file size is over 17Meg. Shouldn't the historical data log file only have traces for items that are checked to log data??

[andreoliveira 47]

Hi,

You should see as many traces available as the number of traces you have in the .scf file, when you check the box defining not to log the data all you are doing is telling Citadel not to stamp the value of that specific tag, however in the Database structure you are supposed to have all the traces defined in the .scf file, even though you might not have data for some of them.

Best Regards

Andre Oliveira
Applications Engineer
National Instruments

[unclebump]

What started this question is a problem that I am having reading historical data out of the CITADEL database. I have a vi that reads 8 tags of historical data, inside a for loop, using the read historical trend function. When I run this data with no other vi's open it will work fine. If I run this vi at the same time my data collection vi is running, it will not return data for most of the traces. It is showing an error code that I have listed as another discussion topic item. It seems like maybe I have a resource conflict when the tag engine and everything else is running.