FrSky telemetry

hello everybody
I try to build VTOL plane. I use the latest plane firmware, a Mateksys H743-MINI and a FrSky RX6R (ACCESS). For Telemetry I connect the receivers SPort to TX7, which is SERIAL1 in the firmware.
The first problem is that only protocol Nr 4 is working. Protocol Nr 10 as suggested here does not. I try different options as suggested, but I never saw telemetry working.
Second problem: With protocol Nr 4, I see a couple of values, but some of them seems to be dead (always zero). It seems that for example Vspd, Temp1, Hdg, VFAS is living, but Alt is not. Is there any known problem why Alt is not living? In the Mission-Planer I see a correct “Alt” value!, but it seems it does not find its way to the receiver, at least not with protocol Nr 4. And protocol Nr 10 is not working. :unamused:
thanks for any feedback, Gerd

Both SERIALx_PROTOCOL 4 or 10 work …

For S.Port telemetry you need a signal inverter. With your FC it works directly with


For SERIAL_PROTOCOL = 10 you have to install the Yaapu script to see the telemetry data.

thank you Reinhard for your quick response.
So I understand, that the LUA script is mandatory for pass-through (= proto 10). I thought it is optional.
But protocol 4 should work out of the box, right? There is still no valid number for “Alt”. It is always zero, although mission planner shows right values, and while other data work, as I wrote. Is there any idea what could help for this case?
regards, Gerd

Maybe this will be helpful, in older versions of FrSky RC link( DJT module + ER9X firmware in 9X), the alt value was on screen where was GPS coordinates, then it was able to “trim” alt in radio.
Maybe You can do same in You’re radio?