The communication to the drive is with com cable through the COM port of the computer. The communication can get lost if the com port of your computer has changed. You can find the com port numbers under Device manager of your computer. If there are more than one you have the try them one by one.
Once you determine the com port number in the computer you need to define it in the test file. See below. Below screen is under Options > Hardware of RM6 software.
Define the com port, hit apply and save the file. Then Scan your drive again. If you get the same error, try the other com port if there is any.
Should you have any further questions, please open a ticket by clicking "New Support Ticket".
Geocomp Support Team