I would like to use the built-in Data Logging feature. There is the "Log at Completion" option, but is there a way to programmatically make a new log record while running? I looked around in VI server and couldn't find any methods that would do that. Currently, I am grabbing all of the front panel control references using VI Server and if there are any changes, the changed values are written to a log file along with a date/time stamp. I'm mostly dealing with buttons, which simply change from 0 to 1 or 1 to 0, so it's not too hard to visualize what was pressed. It works okay for reconstructing what happened, but it would be much nicer to use the built-in fe ature because you can "replay" directly onto the front panel and actually see what the changes were. However, without being able to programmatically make a new log, it won't work for me.
I would suggest using your own code for datalogging. The datalogging you are referring to is primarily for debug, and one shot datalogs of front panel indicators (and controls?), not including graphs, etc.
If you go to the file functions, you will see a menu for datalogging. These functions will allow you to save your data, as you need it, simply, and in a compact format.
I recommend opening the datalog file, doing all your file operations, and closing the file before the program is complete. There are several examples of this in the examples database.