I was able to turn on and off the relay output with pins 54 with radio control .
I would like to control a second realy output , pins 55 , with radio control but it does not seems possible.
http://discuss.ardupilot.org/t/pixhawk-relay-2-output/6245
Seems that even if you can have a 4 relays configuration with your Pixhawk via BRD_PWM_COUNT, only one relay can be controlled by the radio the other relays can be controlled only with waypoint mission commands.
Releases of ArduCopter 3.3 and below do not have code to implement multiple relays. I implemented changes that enabled AUX3-6 to be used as relay outputs and submitted a a PULL request for the changes to be integrated into the base release of ArduCopter 3.4.
Since we don’t use Pixhawk anymore, I don’t know if the code made it into the ArduCopter 3.4 or not. Good luck.
Thanks for your reply and confirmation oldmogy .
A pity that multiple relays by radio control are not supported by current releases hope in next ones they will.
Btw what platform are you using now ?
We have moved our attention back to fixed wing aircraft of various sizes, using both Piccolo and customer flight controllers. They are not hobbyist aircraft though. If we find a use for the multi-rotor aircraft again, then I’m guessing we will stick with Pixhawk as it has been quite good and it’s nice to be able to modify the firmware if required and contribute something back to the community. My personal aircraft are all at the other end of the scale - ie 250 miniquads and smaller. They are quite a contrast to my everyday work aircraft lol …