Ed,
What kind of "data logging" are you looking for?
The EMS streams all the values out of the back of the unit on a serial port. You can capture this into a text file and display it in Excel, assuming you have a laptop plugged in. Or you could write a program to do this, as all of the data protocol is in the uder's guide. We do the same thing on the EFIS.
If you want internal data logging, that is something we would like to do in the future, but we don't have a date for you. It's a complex problem, involving memory inside the EMS, a user interface to set up the datalogging, a way to download it to a PC, and a PC program to display it. Not easy, unfortunatley.