Control & Measurement EUPP Modules - PWM Board The Pulse wave modulated (PWM) function is provided on the main board, but the PWM signal is not isolated. If full isolation is required the PWM board can be used, this module takes the PWM signal from the main board. Full isolation is provided with on board opto-isolation and an on board power supply, which develops control voltages from a plant side DC supply (7V to 30V).