I have issues connecting RM to live NMEA data using a virtual port on my PC.

Whereas if I use Visual GPS View or Serial Port Monitor (both trialware), I can see the live NMEA strings.

I've tried using separate ports for Position and Depth. I've also tried RM1.

Here's an attached sample of the NMEA strings. Note I'm using virtual com ports (app is called Virtual Serial Port Driver Pro) to receive the NMEA data & another for RM to read it.

Hi Darren,
Could you please describe your configuration in more detail. Where is the GPS data coming from originally, and how do you have your virtual COM port utility configured? Are you splitting the port, or piping data from one port to a virtual port? It would be good to get to the bottom of this, as I know some other users have had trouble with virtual COM ports in the past, but we have not been able to reproduce the problem here.

Hi Matt,

Mission Planner (if you're not familiar is ground control software for Ardupilot autopilot boards) will stream NMEA to a port on your pc. The autopilot board has an external GPS antenna.

I created a bundle of serial ports (COM20 & COM21), effectively piping data from one port to the other as you say. For example I use Mission Planner and select COM20 to receive the NMEA data. In RM I select COM21 as the NMEA input port.

Looking at the Ardupilot forum, Mission Planner writes time as hhmmss.fff and not as hhmmss, hence there's a decimal component which is not the NMEA standard as I understand. I was pointed to this file which stipulates how Mission Planner writes the NMEA strings. github.com/ArduPilot/MissionPlanner/blob.../SerialOutputNMEA.cs . I've made my own version of the same without the decimal time stamp values, removed writing the RPY string and added a DPT. A colleague at work will be able to help me implement this change on Mission Planner and I'll post an update on how it goes. Cheers!