Explain M303 parameters?

[handyandy]

In the M303 command used for PID tuning it uses parameters Hnnn for the heater to be tested, Pnnn for the PWM to be used (usually 1.0) and Snnn for the target temperature.
I can understand the H and S parameters but what is the P used for, and when would you use it?

[bearer]

I use P0.7 for my heater as it used to be a 19V supply, and now with 25V it would be "too powerfull" so I use the P parameter to limit it to 70% duty cycle and end up with seemingly the same power as before.

[deckingman]

@handyandy This should help https://duet3d.dozuki.com/Wiki/Tuning_the_heater_temperature_control

[handyandy]

Thanks for that.