In the case where the driver is not working, you can always troubleshoot with HyperTerminal.

Using TeraTerm or HyperTerm, you can send commands to the serial port and see the responses coming back. Connect to the system controller's serial port using terminal program of choice. Press Ctrl +  j to send an LF character and the controller should respond with an E indicating that the command was in error since there was no actual command.

Using the checksumcalc.exe program, enter a command in the command box. Press Calc Checksum, and press Copy to Clipboard. Switch to terminal program and paste the command, and press <Enter>. This will only work if you have the terminal program set to send a CR LF pair when enter is pressed. If this is not the case, then you can press Ctrl +  m and then Ctrl +  j to send the CR LF pair.