Pixhawk 2 and TL65B44 landing gear

Can I connect TL65B44 landing gear direct to AUX port on pixhawk or a I have to connect only signal line to pixhawk and power from anoher source ( directct from PDB forexample) ?

They pull way too much power. You need to power them separately.

Can I power servo rail by 6v BEC ?

The output rail is not designed to be a power bus. If you have low power servos you can probably get away with it but it is not good practice.

I thought the servo rail was expressly designed to be a power rail?

  • Servo rail high-power (max. 10V) and high-current (10A+) ready

No it is an output rail. It was expressly disconnected from internal power so it could not power anything especially from internal power. It is not uncommon for people to connect a BEC to it and they can get away with it for low power applications but anytime you connect something like servos or retracts they can produce power spikes on the bus that could cause problems to the flight controller. I don’t want my flight controller, that keeps my aircraft flying, subjected to anything that could interfere with it’s primary job.

With the Pixhawk 2 a custom carrier might easily be designed to be a power distribution bus on the output.

If that’s the case then a big fat warning should be put in the docs and on the wiki page, as yes it’s a major risk to the flight controller. But the wiki page and the product docs say it’s a high current servo rail:

Servo rail high-power (7 V) and high-current ready

I’ve certainly powered landing gear off it with no problem, but would like to know if that’s wrong. @proficnc?

Anytime you pull high current spikes near a microprocessor you need to be careful. You can get impedance spikes that travel down the ground lines and disrupt the ability to evaluate a one vs a zero.

I can’t see any issues having a landing gear servo on the servo rail.

The rail is not used to power the flight controller,