Switch Instructions: The HS/MS CAN switch direction (when looking at the front side of the scanner):

Toggle Switch Up : HS CAN
Toggle Switch Down: MS CAN

You will know if its set to HS or MS when it's connected to the software and if the vehicle connected requires HS/MS CAN to communicate. 

When FORScan establishes a vehicle connection, it analyses the vehicle configuration. If MS CAN modules are expected, FORScan will ask user about HS/MS CAN switch and ask you to confirm. If it's in the normal (off position), it will just ask you to turn it on.

If no question is asked, it means FORScan doesn't expect a presence of MS CAN and is not going to look for it. If user confirms the MS/HS switch presence, FORScan will ask user to move the switch position