Faulty Herelink Joystick or MG90 Tower Pro Servo -

I am placing this video link below to let me have your feedback as to what could be wrong here. Is it the servo or the Herelink right joystick ! The servos are acting for the pitch of a V-tail plane . I have switched the pwm_main channels and tested . The result is the same on the left joystick .


To verify if the joystick have problem, go to RC calibration page to verify the sbus input. Then turn on the tuning screen in Mission Planner, select chXin and chXout and see if they are consistent.

To verify if the servo have problem, Connect it to PWM out 5 or beyond. Then go to Servo/Relay tab in Mission Planner and trigger them one-by-one.

You may also have incorrectly setup the servo function parameter
The v-tail setup is slightly different from standard planes

I am using Px4 stack with QGC. Can i test the functions based on your comments .

The link for the Main servo output for Px4 is here

The directions for a V-Tail is as explained in this youtube

The Ardupilot link indicating the positions of the control surfaces may be a typo error. Can you be sure these are correct movements for a V-Tail

For the servo test, you can do this here:

For RC in and out:

Good Day

When I use the motor slider tool, the respective servo channel is moving the servo but also the throttle is actively starting the Channel 5 as well. Is this correct ?
On each channel, I have the motor work momentarily along with the respective servo !!
Also I am not seeing the respective servo moving back to its original location after the slider automatically moves to its zero position !!


Can you please request the Ardupilot forum regarding the link ( https://ardupilot.org/plane/docs/guide-vtail-plane.html) which you provided to correct their basic concept of the V-Tail configuration. It is described incorrectly.

thank you

This sounds strange. You may check if there are more than 1 RC_MAP parameter being assigned with a common channel.

Test a different servo to verify if that single one is malfunctioning.

We do not manage the Ardupilot wiki. Please raise an issue on the wiki’s github or report this on Ardupilot forum.

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Ardupilot forum has been resolved…they told me that is related to stabilized mode and nothing to do with commands send by the remote controller…

" Test a different servo to verify if that single one is malfunctioning." -
The issue remained same with all servos. They don’t return back to the original position while the slider returns back to zero. It is also very unlikely all my servos are faulty !!

You may check if there are more than 1 RC_MAP parameter being assigned with a common channel.
No channel overlapping is seen .

Also in stabilized mode with throttle, I am seeing more confidence in flying as on the ground with throttle, everything works as it should automatically !!


Do you have any idea regarding the following parameters

a) RC_map_Stab_Sw . What does this do ? It is kept as " Unassigned" although in
Herelink under flight modes, i have assigned the stabilized mode to channel 5.

b) RC_map_Param1 - What does this do ?

c) RC_Map_ PosctL-SW - What does this do ?

d0 RC_map_Mode_sw - What does this do ? it is currently unassigned

Please check the PX4 wiki

Actually this is the problem. I already went thro’ this section and there is no explanation on the subject. Is there any other technical reference on these values !

This question is about PX4, you should ask this on PX4 forum as they should explain this more detailly.

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OK. Will do that . thank you

I have two more queries down here .

  1. It is showing " parameter cache CRC match failed "

  2. " Critical not enough Bandwidth to enable log streaming "


I was able to remove the above queries by unchecking the parameters within the " CONSOLE" menu settings for logs