Hello Fred
First, set your radio for low speed data operation per page 9-17 of the Advanced Instructions manual.
The GPS functions should be off.
Set DV DATA TX to AUTO.
Next, create a radio connection in D-RATS.
Menu>File>Preferences>Radio>Add
Name = Radio
Type = Serial
COM Port = where your radio is connected
Speed = 4800 or 9600
Click Add
Click Save
Use the Drop-down arrow at the bottom, left of the window to select the radio connection.
Good luck and 73
Patrick (N3TSZ)
Patrick Connor