With Graupner HoTT radios you can use fully digital, single-line SUMD protocol. For the connection only normal servo cable is required.
Connect the cable according the photo. In the unit the cable is in the RUD port. In the receiver it is always the last channel. For GR-12/GR-12L it is output with label "6".
If you have not connected a power supply, you can connect the BEC cable or 1-2S LiPol now (even without a servos).
2 Spirit Settings
After initialization of the unit you can start the software. To allow the connection set the Receiver type to SRXL/SUMD in the General tab.
Now save the settings (CTRL+S) or in the Backup tab/Unit - Save.
3 Receiver configuration
By default SUMD transmission is disabled in the HoTT receivers.
It is necessary to enable it in the (F) Function/Telemetry/Setting & Data View menu (HoTT MZ series).
Change SUMD at CH6 to YES.
Now you can restart the unit. After the initialization the SUMD connection will work. Reverse of some channels might be necessary depending on the radio model - please check the Diagnostic tab.
The transmission is able to carry all the channels. Usually SUMDOF12 option (if available) is fine.