Pixhawk only sending input to one servo on Y Splitter cable?


I have a Dragon Link transmitter receiving inputs from a Taranis FrSky, with the dragonlink sending inputs to RC IN on my Pixhawk using SBUS. My ailerons have two servos which are designed to be connected together on one input via a Y Splitter cable. I can confirm that connecting directly to the receiver on my plane enables the aileron servos to turn in coordination together. However, when I connect the servos to my Pixhawk, if both servos are connected on the Y splitter cable, only one servo moves when I give aileron input. If I switch the cable around, or unplug one, the still-plugged-in servo moves the other aileron which was not moving before.

Am I missing something about my servos being somehow individually addressable? My understanding is they are simple PWM outputs from the Pixhawk. Is this some type of voltage issue on the Pixhawk with my splitter cable? I’ve searched around for this but haven’t seen anything on it.

To update, I tested out the splitter/servos by bypassing the pixhawk and plugging directly into my receiver. They both worked fine there. So must be some issue with the pixhawk (which really sucks, I took forever troubleshooting and hooking everything up). Has anyone heard of this? Is there some voltage drop issue I am causing by using a y splitter?

Just to update for anyone coming across this in the future, the QGroundControl Radio Configuration page allows you to passthrough input on the AUX 1 & 2 Channels of the Pixhawk board. I chose to pass through the Aileron and Flaps channels through these two, removed my splitters, and connected the second aileron and flaps servos to the Aux 1 & 2 servo channels on the Pixhawk board. This is very much not ideal, so if anyone has other ideas for me to try, would appreciate it. Thanks!!

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Check with the Pixhawk schematics:

Voltage levels could be different between receiver and Pixhawk.

You should be able to configure the TX so both channels work off the same stick, there by emulating the splitter.


Were you able to improve on this Aux channel setup for trigeering other devices