E classic GPS position selection logic

[lotharjt]

Hello, I have a dual E120 installation with a network switch, DSM300 and a S3G course computer pilot. It appears that the plotter is receiving GPS position data from the RS125 sensor via either Seatalk1 or view the NMEA 0183 output from the pilot. Short of tracing the wires, can I tell via the menu selections at the plotter?

I've also noted that the GPS sensor page at the plotter never shows any status info at all, all fields are blank. So I'm wondering what that means.


And now, I've recently added a third party Class B AIS. The AIS data is interfaced tot he NMEA port of the slave plotter. Everything is working fine in display of AIS data but I have noticed that with the AIS on, the plotter appears to be using the GPS position from the AIS, as that position data is also on the NMEA output from the AIS.

So, it appears the plotter will select in a priority scheme which input port it looks at for GPS position data, true? What is that scheme? The net results seems to be that I now have some redundancy built into my installation. The AIS position will be used if available and if that fails, then the RS125 data will be used.

Oh, I should also say that when the AIS is on, the GPS status page does show some data, HDOP, Fix status, Lat - Long position but no satellite status.

Thanks in advance.