Change Name of Duty Cycle to PWM

[oakbarn]

On the Process page, change the name of Duty Cycle to PWM, which it is and refered to elsewhere in the wiki.

[JonW]

On the Process page, change the name of Duty Cycle to PWM, which it is and refered to elsewhere in the wiki.

No, the duty cycle and PWM are different.

[brahn]

Both Duty Cycle and PID modes use PWM, so I think it would be confusing to label only Duty Cycle as PWM.

[crane]

If you want to get all text book on this topic, PWM (pulse width modulation) mimics an analog output by varying the on/off time (duty cycle) over a fixed period. So a PWM output with a duty cycle of 25% and a period of 1 second would correspond to a digital output being on for 1/4 of a second and off for 3/4 of a second, repeating over and over. So duty cycle is one of the 2 variables that makes up a PWM type output. Now PID is a closed loop control algorithm that varies the output to control a process based on feed back of measuring the thing it is trying to control. In our brewing application the PID loops use PWM to control the process, and they do that by varying the duty cycle with a fixed period. So technically speaking PID uses both duty cycle and PWM.

In the brewing world when we refer to PWM and/or duty cycle we are really just referring to "open loop" control. To further complicate the terminology some PIDs refer to automatic mode for PID closed loop control and manual mode for open loop control with no feedback from the thing we are trying to control. So in the end it really doesn't matter if you call open loop non-feedback control PWM or duty cycle.