QUAD - RTL mode - RCOU.C1 and RCOU.C2 diverging


my copter is Quad
so ESC are connected to my PX4 v3 running copterV3.5.3.
Last November 1st, my copter crashed.

Having a look to Logs 30.BIN , i see that RCOU.C1 and RCOU.C2 are suddenly diverging few secs before it crashed. For some unknown reasons PWM for RCOU.C1 dropec and PWM for RCOU.C2 jumped. So quad starts to flipp over .and crash …
i do not understand why? flightMode was RTL…

Any help would be highly appreciate.


according to esc numbering, i should say that pwm values for RCOU.C1 and RCOU.C2 should be aroud the same. as well as RCOU.C3 and RCOU.C4). My quad is for photos not accro …

RC OUT 2 is motor 2. It failed.
Are you using Bullet connectors.?

Yes i am using bullet connectort to connect motors to esc.
Why ? Any issues witth bullet connectors?

In my previous message
RCOU.C1 is for motor 1
RCOU.C2 is for motor 2
RCOU.C3 is for motor 3
RCOU.C4 is for motor 4

How do you understand that motor2 failed is pwm value from RCOU.C2 is getting higher…?

Hi, I am not an expert., but bullet connectors can fail.(once happened to me).
when a motor looses power that side will go down and FC will increase PWM to keep it level. opposite motor will be lowered.
After checking motor rotation direction, it is better to direct solder the motor-esc connection.

It could just be that the battery is dead. Try graphing CURR.Volt. The voltage is way down at 11V (and it’s a 4S battery) at the time of the crash.

@rmackay9 Hi Randy, in quad copter RCOU.C1,RCOU.C2,RCOU.C3,RCOU.C4, are the pwms of four motors? And where can I find it in the code?

@FireFly The RCOU fields are all of the PWM signals that the Pixhawk outputs. In copters, the first 4, 6, or 8 outputs (quad, hex, octocopters) are motor outputs by default. They can be changed with SERVOx_FUNCTION parameters.

Here is where the Dataflash logger creates the RCOU packet in the code. It reads each servo PWM output for channels 1 to 14, which correspond to each of the SERVOx_ parameters. For example, if your SERVO1_FUNCTION = 33, then RCOU.C1 will be the PWM that is being sent to motor 1.

The RCIN fields are the PWM input signals that the Pixhawk is receiving, and the first four channels usually correspond to roll, pitch, throttle, and yaw from your RC transmitter.


@Anubis Tks so much!