I got the Scan XL Standard software free with the purchase. (They say it's a clearance deal.) So I only have to pay for the GM Enhanced add on. Look at the other hardware purchases. I believe those packages make one purchase the Scan XL Standard software for $79 or so.
For example, look at this page...
http://www.scantool.net/scan-tools/obdlink-mx.html
Then look at this page...
http://www.scantool.net/scan-tools/obdlink.html
I mean the Scan XL software is required to run the GM enhanced add-on. And they are giving the Scan XL software away on clearance with the OBDLink model.
The GM add-on looks like some good stuff!
I am going to have to install 'hyperterminal' on this win 8 pro x64 laptop. And see what commands respond to query?
The protocol looks similar to the "Hayes protocol." Used to program old modems.