Topcon AGI4 - No NMEA output?

Hardware Autosteer
1

Hi all,

i’m in the process of building a RTK bridge, which works really well. To test it i’ve installed it into a Fendt with TOPCON AGI4 RTK installed. Problem is that i don’t get any NMEA output on Port B (black connector), while the settings in my vario terminal is set to send out the GGA NMEA data.
Did i miss something? Or do i need to connect with it over serial to setup the receiver?

Thanks.

2

I think the nmea data comes out the grey connector to the d-sub 9 connector in the roof. The black port will be the one to send rtcm data into the agi4.

3

You are correct, i got a USB to RS232 converter and plugged it into the SUBD 9 pins connector in the
roof. In my terminal screen i immediatly saw the NMEA messages.

I could also connect to the receiver with the TRU program, i’m trying to find out if i can output the NMEA
to Port B too, not sure so far havent found it.

4

Did some futher testing :slight_smile:

i could set port D (the black connector) to output NMEA messages but :

  • i was unable to read them in my serial monitor, both devices were set at 115200 baud , and i tried
    different baudrates nothing worked, all the data that came in was scrambled.

  • The settings weren’t saved in the GPS, i did ‘Ok’ when i set the Port D to output NMEA data, but when i
    powered the device off and back on, it had reset all it’s port settings. Could the tractor reset these settings?

5

And more info :

After all the scrambled data was a software bug, i fixed it an now i’m able to read it.

But the second problem persists. Whenever the tractor is started, the Topcon reciever gets
a reset of it’s port settings after a few seconds. Not sure why but i guess it’s a way of security.

I’ll need to find the TX somewhere else in the cable loom , and create a second serial port to read
that data.

6

Yes I expect the receiver software had some default settings and resets the port settings on startup, I have found this on an agco agi4 too.
Take the tx from Porta to the ntrip client rx and the ntrip tx to portb rx. This way you get the nmea gga and send the rtcm to the agi4 as it expects.

7

Yes, that’s exactly what i’ve done. I ran into some problems with scrambled data again, but my ESP32 had a spare hardware serial port , so now i use 2 different serial ports with Rx on the one (Tx unused) and Tx on the other (Rx unused).

Works like it should now, thanks.