Sending NMEA to Trimble

I have an CNH FM-1000 (Trimble FMX) which I still use for isobus control of a fert spreader. Its internal gps receiver seems to have failed and it just doesn’t see any satellites now.

Has anyone used an external on one of these? What would be involved in sending NMEA to it from the agopen system?

I’m still using a v2 board and separate ardusimple 2B f9p connected via usb to the laptop. My limited understanding is that I could program the f9p to output NMEA from the a UART and wire that direct to the Trimble display?

Trimble generally accepts external NMEA only for section/rate control and mapping, not for autosteer.

For autosteer you would need external TSIP (which hasn’t been fleshed out by the DIY community), and not every monitor is capable of that (the FMX is capable).

Your understanding of F9P outputting NMEA to the Trimble for ISOBUS control of a fert spreader matches mine. You’ll probably need a level converter from ttl to RS232.