I have Topcon receiver G3 160T. I connect receiver to COM1 with serial cable. I used sample program come with commapi package to retrieve any data from serial port but fail (no data display). I also try MATLAB simple code. Same result. I ran the program come with Topcon CD without any issue. Do I miss anything such as handshaking or init etc? If no idea, any suggest device that I can easily use to get the GPS ephemeris data either using USB or Serail port.