Turn on the Midas DL154 using the power switch on the rear panel. Once the unit has booted up, you can find the software version by pressing and holding the 'Menu' button. The software will then drop into a numbered Menu. Using the Up or Down arrows, scroll round to option 5 - S/W Version.Press the 'Enter' button and the software version the unit is running will be displayed. Pressing the 'Menu' button twice will drop you back to the normal operating page.