The Application of Pulse Width Modulation in SIMATICS7-200CPU22X Series PLC

The SIMATICS7-200CPU22X Series PLC has two PTO/PWM generators that create either a high-speed pulse.The maximal frequency of high-speed pulse is amount to 20 kHz.The Pulse Output(PLS) instruction is used to control the Pulse Train Output(PTO,50% duty cycle) and Pulse Width Modulation(PWM,variable of the cycle time and the pulse width).The PWM generator has a control byte (8 bits) that is used to provides a continuous,variable duty cycle output with user control of the cycle time and the pulse width.In the initialization routine,setting up these special memory bit locations is a key element.There is likely to lead the pulse having no output if the control byte is error.