The software version can be found on the main blue screen when you first boot the control. It can also be found by pressing "Machine Setup" --> "Access" --> "Service".

It will be in yellow letters at the top of the screen.

The software version will always follow the format of "X.X mod X"  Example "3.1 mod 5A" "2.0 mod 8" 

There are some special cases where custom software has been issued for the control... "2.0 mod 8 Special"