It does indeed work over the USB cable. We have a D-Rats group weekly and have a member with a 9700 who has it working. D-Rats just uses a serial connection. I am not absolutely familiar with how te 9700 works, but do have a serial to D-Rats connection on both bluetooth (5100) and USB (7100). Usually either creates 2 comm ports, the first one is for CI V, the second is for serial data. Use the second.
