Thruster PWM parameters

I want to change the parameter file to set the min and max pwm for thrusters connected to main output(1-6) of pixhawk. I couldn’t find this problem posted here and it’s just a simple issue but I couldn’t fully understand the documentation. It’s be really helpful if someone could provide an insight to it.


There is a parameter list with descriptions in our website.
Check MOT_PWM_MAX and MOT_PWM_MIN, probably that’s what you are looking for.

@patrickelectric unfortunately… there is a bug with your suggestion: Sub: SERVOn_MAX and MOT_PWM_MAX have no apparent effect. · Issue #10488 · ArduPilot/ardupilot · GitHub

@SatyamAmbast Why do you want to limit the outputs?

You can try to decrease the pilot gain input with the joystick buttons, or set a current limit as a workaround.

We are working with limited current and need to make it so that the thrusters don’t drain too much current. It’d be preferable if maximum pwm can be limited by software. So I assume the gain_inc and gain_dec buttons are what you’re talking about. How can setting the gain to 25% affect the pwm applied at full throttle.

A 25% gain will scale down all pilot inputs to 25%. You can still get some higher outputs in stabilize or depth hold mode depending on the circumstances.

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Did you find any solution that works OK? Having the same issue with thrusters drawing down the voltage and killing the companion computer

Hi, I have a similar need to modify the pwm trim and upper and lower bounds for the motor outputs on pixhawk chanels 1-6. The output is not responding to the MOT_PWM_MAX parameter or the RC3_MAX indicated to override it. In my case, I need to expand the range rather than constrain it. Has anyone found a workaround in the year since this was last discussed?

So as Mr. Jacob discussed above there is a bug because of which MOT_PWM_MAX and MOT_PWM_MIN have no effect on the PWM that is fed into the Thrusters. I’m unsure if the issue has been fixed by now because I haven’t been up to date with the current state of the ardusub firmware. The workaround we used was to simply limit the pilot gain to 50%, such that at full throttle the pwm output was 1700 or 1300. Obviously this isn’t the most elegant or customizable solution but this worked for us. I hope this is helpful in some way.