# Thruster PWM parameters **URL:** \ **Category:** Blue Robotics Software\ **Created:** [April 11, 2019, 3:16pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826 "2019-04-11T15:16:01Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![SatyamAmbast](https://avatars.discourse-cdn.com/v4/letter/s/838e76/32.png) [@SatyamAmbast](https://discuss.bluerobotics.com/u/SatyamAmbast)\ **Post date:** [April 11, 2019, 3:16pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/1 "2019-04-11T15:16:01Z")
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. Thanks! ---
**Author:** ![patrickelectric](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/patrickelectric/32/2162_2.png) [@patrickelectric](https://discuss.bluerobotics.com/u/patrickelectric)\ **Post date:** [April 11, 2019, 3:20pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/2 "2019-04-11T15:20:21Z")
Hi, There is a parameter list with descriptions in [our website](https://www.ardusub.com/operators-manual/full-parameter-list.html). Check MOT\_PWM\_MAX and MOT\_PWM\_MIN, probably that’s what you are looking for. ---
**Author:** ![jwalser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/jwalser/32/2234_2.png) [@jwalser](https://discuss.bluerobotics.com/u/jwalser)\ **Post date:** [April 11, 2019, 6:17pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/3 "2019-04-11T18:17:52Z")
@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](https://github.com/ArduPilot/ardupilot/issues/10488) ---
**Author:** ![jwalser](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/jwalser/32/2234_2.png) [@jwalser](https://discuss.bluerobotics.com/u/jwalser)\ **Post date:** [April 11, 2019, 6:18pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/4 "2019-04-11T18:18:40Z")
@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. ---
**Author:** ![SatyamAmbast](https://avatars.discourse-cdn.com/v4/letter/s/838e76/32.png) [@SatyamAmbast](https://discuss.bluerobotics.com/u/SatyamAmbast)\ **Post date:** [April 11, 2019, 7:43pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/5 "2019-04-11T19:43:37Z")
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. ---
**Author:** ![williangalvani](https://avatars.discourse-cdn.com/v4/letter/w/6f9a4e/32.png) [@williangalvani](https://discuss.bluerobotics.com/u/williangalvani)\ **Post date:** [April 12, 2019, 12:32pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/6 "2019-04-12T12:32:31Z")
Hi, 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. ---
**Author:** ![eirikaso](https://avatars.discourse-cdn.com/v4/letter/e/a8b319/32.png) [@eirikaso](https://discuss.bluerobotics.com/u/eirikaso)\ **Post date:** [June 6, 2019, 10:18am UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/7 "2019-06-06T10:18:56Z")
@SatyamAmbast Did you find any solution that works OK? Having the same issue with thrusters drawing down the voltage and killing the companion computer ---
**Author:** ![D-Eng](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.bluerobotics.com/d-eng/32/7951_2.png) [@D-Eng](https://discuss.bluerobotics.com/u/D-Eng)\ **Post date:** [July 30, 2020, 11:39pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/8 "2020-07-30T23:39:37Z")
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? ---
**Author:** ![SatyamAmbast](https://avatars.discourse-cdn.com/v4/letter/s/838e76/32.png) [@SatyamAmbast](https://discuss.bluerobotics.com/u/SatyamAmbast)\ **Post date:** [July 31, 2020, 5:55pm UTC](https://discuss.bluerobotics.com/t/thruster-pwm-parameters/4826/9 "2020-07-31T17:55:36Z")
@D-Eng 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.