Hello Dan
(i suppose you are using a DB-9 to 8 minidin cable)
I've a QY70 and somewhat of experience with "to host" cables and issues
have you checked the speed of the serial port?
remember it must be at 38400 bps
this setting is not set automatic by the installer, it has rather to be se manually
on the control panel->system->ports->COM1
hope this helps