GRAUPNER MZ24 PRO & GR 18 Receiver (SUMD) and Pixhawk 4 Problem

I have problems with RC connection, I am using MZ24 Pro transmitter & GR18+3xG+3A+Vario Hott Receiver for Radio System . This model uses SUMD protocol, I try to connect SUMD signal channel ( Channel 6 ) to PPM and DSM / Sbus ports on Pixhawk 4 but RC data does not work properly ( for DSM / Sbus port) or I am not getting signal on Qgroundstation ( for PPM port). Does PX4 software and Pixhawk 4 support SUMD signal or Am I doing something wrong? I found some forum topics about this issue but most of them are related with Ardupilot projects and Pixhawk 1. Also I can not find any info about SUMD on documentation pages ( Pixhawk 4 Radio Control & Radio Systems ) . Thanks for your help

1 Like


I think you need to update the hott to the newest version, and that supports serial

For instance the GR-12L has SBUS

The GR-18 does not

Thanks for help, I will try this.

You are welcome, I think the pixhawk does not support SUMD BUS only SBUS, another solution could be (I have no tried yet) to use a PPM module

I don’t understand , PX4 project has codes for SUMD signal type
( here --> & )
Using a PPM module is one of the solution,you are right, but I don’t want to use a PPM module for this PRO Radio System :slight_smile: Thanks for helps .


Neither do I. well, I have the GR-12L HoTT and the only thing it supported was SUMD. I did not work at all, I was quite frustrated. However, when it was upgraded to the newest version that supports SBUS it worked quite well. So I suggest you can use a GR-Hott receiver which version supports SBUS. Cheers :slight_smile:

However, you can also contact the central Graupner group for a more professional help :slight_smile:

I have pixhawk mini and GR-12L HoTT and RC MZ-12

I contacted with The message is here;

“SUMO have only an GR 12 , Gr 16 , GR 24 or GR 32. The Gyro Reciever have only SUMD her you can change nothing.”

I think I will use PPM encoder :stuck_out_tongue:

Well, At least you know the problem now and how to solve it :slight_smile: and I wish you all the good in that issue :slight_smile: