This device is very usable for diagnose of serial (RS232 or COM) port in PC. If you are servicing mobile phones, you may face problems with connection (cable not working or software is not sending transmission to phone) you can check if software is working correctly, once the transmission is ok, you will see the proper LED`s shining.
This device is totally transparent for the signal. It does not couse any errors/noises to the transmited signal.
