PixHawk3 and echosounder with NMEA output

Hi @rmackay9,

I seem to be having some issue with hooking up the SonarMite SM4/BTX to my Pixhawk2.1.
I updated the Pixhawk to the latest firmware. I purchased a RS232 to TTL Converter and wired it up as shown (I even did testing to make sure I had the correct cables from my sounder unit). Once all hooked up, I keep getting bad LiDAR Data in MP. I also notice that my unit isn’t logging data. I connected via bluetooth to my sonar unit with my pc and logged data in hyperterminal, which it then works. While this is logging no output goes to the RS232 port (I assume as no changes previously).

I got to a stage where the pixhawk didnt say bad lidar, only bad ahrs (not an issue) but then i switched wires while plugged in and it says bad lidar. Swap again and it goes away. All the while no data logging on the unit.

Not sure if I’ve got a dud RS232 to TTL Converter or whether I would need a RS442 Convertor? I didn’t think so, considering the unit can work via the serial cable to a Windows CE Data Collector for survey work).

Seems that the pixhawk isnt sending a ‘start’ command to the logger to start sending the data? And I assume NMEA 0183 data is all the same? It has 2 lots being DBT and DPT. (It auto reads what data it needs to send). Sort of a bit lost for ideas, I’ve checked all the serial parameters in MP and gone from 2400bps to 115kbps. It is currently plugged into TELEM2 on the pixhawk 2.1 also.

Any ideas would be greatly appreciated.
Thanks, Scott.