I own the APM 2 since 2 months build in a MPX Cularis, the plane is ready for fhe first flight, and short time before I updated to 2.60.

I use CH 5 for the second aileron and CH 6 and 7 for flaps in manual (RC6,7_FUNCTION 1).

But with 2.60 my CH 6 Servo is not working anymore, allthough RC6OUT shows the right values.

I can change RC6_FUNCTION to 0 and back to 1 but nothing happens on the servo

The only workaround that works, is changing the value to 2 or 3 and then back to 1. After this,the servo works.

But when I reset or power off, function of CH 6 would be lost, allthough RC6OUT values are still ok.

I openend issue 725, within this other people have similar issues to CH 5 or CH 7, but CH5 and CH7 is working fine for me.

Strange ....

I already updated PPM Encoder to 2.2.68 but the issue still persists.

I am not sure, if I should make my first flights with 2.60 this weekend, maybe other issues could occur.

Maybe someone could help?



PS: Sorry for my poor english

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I'm not an arduplane expert but i have a little experience with the channel-aux stuff which is what you're struggling with.


When you say RC6_OUT doesn't work you're looking in the mission planner's status screen where it shows all kinds of information from the APM?


Of course after changing the FUNCTION of the various servos through the mission planner you're pushing the "write parameters" button?

I have seen a similar issue on my plane, where it appears the [Aux] channels ( 5-7) are not being initialised properly on powerup.    changing any of the RCX_FUNCTION values to something different, then writing the settings to the plane, and then changing it back ( to where I want it) and writing the settings again, seems to cause the aux channels to initialise properly. ( untill the unit is powered down again).     It doesn't always do it on all channels, but the channels it does do it on are consistent, even if relocated.  eg if I have a gimbal on 5&6, and 5 is giving me the problem, then relocating the hardware ( servo lead ) to channel 7 and changing hte software to use channel 7 instead does NOT fix the problem.

When RC6OUT does not work, the Servo did not work, The status in Mission planner shows the right output values. I am sure that I write the changed values every time to the APM. The MP log shows the writing of the parameter also correctly

When I changed the value to 0 and back to 1 the servo did not work. Tested it several times, and I am very sure that I write the values every time to the APM.

Only if I change the function to a value above 1, and the back to 1, the servo will work. But only till reset or power off the APM2.

Earlier I did some tests with self builded FW. The issue seems to persist long time before 2.60.

In 2.50 I did not have this issue (but other).

Did some further tests:

set CH 6 and CH 7 to manual (RCX_FUNCTION=1): Servo 6 is dead, Servo 7 works.

Set CH 7 to flap (2) servo 6 and 7 do not work.

Set CH 7 to flap_auto (3) servo 6 and servo 7 work.

Very strange behavior. First I thought that two aux channels could not have the same function (1) but that was not (CH 6=1, CH 7=2 did not work)

I think there is more than one bug in RC_Channel_Aux and RC_FUNCTION.

I could be mistaken but I swear I remember that the RCX_FUNCTION should be changed to "4" to enable the output channel. Take a look at "Optional Additions" in the Wiki, then Multiple Aileron Channels. Also, you did say that the Config Screen in the MP is behaving appropriately, right? Double check function in Manual, RTL and Stabilize.



I think the issue should be fixed in REV acc021c81993

I will do some tests in the evening.

Yes, I think you may be right.  I just found that little bug in RC_Channel_aux while trying to sort out an arducopter camera mount problem.  It was very mysterious, "why won't the #$% roll servo move?!" until I found a little typo in the lib.


My test was not successful. The issue is still exactly the same :-(. Maybe you can talk to Andrew Trigdell who wants to test it (issue 725).


I have a similar issue with APM2.6 with ArduPlane V2.78b (f0615253) firmware. 

Missionplanner doesn't show any changes for channels 5,6 or 7 when I flip the switches. Signal is ok. Tested with servos and by connencting the m to APM inputs 1-4. Mode select on input 8 works also.

Also tried all kinds of RCX_FUNCTION values. No help.

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