According to quad delta platform, aux 3 is used for connecting throttle. how can i change it from this to another aux ch?
You would need to change the mixer
I see but how to define the output channel.
See http://dev.px4.io/concept-mixing.html. In each output channel, the mixer file should declare
M:
O: <-ve scale> <+ve scale>
S: <-ve scale> <+ve scale>
Count the number of M: and Z: defined so far.
If you need to pad it (skipping Aux 3 for example), simply define a NULL mixer using
Z: