====== Advanced PWM Configuration for Thermal Control ======

**Pulse-Width Modulation (PWM)** is a fancy term for a simple concept: turning a switch ON and OFF really fast. By doing this, we can control "analog" things—like dimming an LED light, controlling the speed of a fan, or regulating the heat of an electric heater—using a digital switch.

===== 1. The "Group" Rule =====

<alert type="danger">**Important:** On many controllers, output terminals are organized into "Groups." Think of a Group like a power strip where every socket must blink at the same speed.</alert>

**The Rule:** You can choose *how long* each socket stays ON (brightness/heat), but they all must share the same *speed* (frequency).

**What this means for you:**
  * Do not plug a high-speed device (like a Fan) into the same Group as a low-speed device (like a Heater).
  * If you change the speed for the Fan, you might accidentally break the settings for the Heater.
  * Always check your manual to see which outputs belong to which Group.

===== 2. Setting the Parameters =====

You cannot set the frequency directly in your code. Instead, you configure the **PWM Cycle** and **PWM Prescale** in the Properties panel of the controller.

{{ en:tutorials:pwm_00-pwm-device-settings.png?600&direct | PWM Device Settings in Properties Panel }}

These settings determine the base frequency for the entire group of outputs.

===== 3. Preventing "Glitches" at Startup =====

When your controller first turns on, you don't want your heaters or fans to pulse randomly while the system wakes up. Follow this "Safe Start" order in your program:

  - **Step 1 (Safety First)**: Force the output to **OFF** initially.
  - **Step 2 (Set the Rules)**: Tell the system what speed and power level you want.
  - **Step 3 (Go)**: Only *after* the rules are set, switch the "PWM Enable" to **TRUE**.