Configuring Pulse Width Modulation (Pwm) Operating Mode - Siemens SIMATIC S7-1500 System Manual

Configuring
7.9 Configuration of digital inputs/outputs (X142)
Further information
You can find more information on the Event/period measurement operating mode in
Assignment of the control interface (Page 131) and Assignment of the feedback interface
(Page 132).
7.9.8

Configuring Pulse width modulation (PWM) operating mode

Areas of application
You can use pulse width modulation (PWM) to generate periodic pulses with a constant
rated voltage and a variable pulse duration.
Possible applications for pulse width modulation (PWM):
● Control of proportional valves and directional valves
– Energy savings as a result of a reduction in holding current or for controlling the valve
● Heating control, for example, via an external additional power unit
Principle of operation
With pulse width modulation, a signal with defined time period and variable pulse duration is
output at the digital output. You use pulse width modulation to vary the mean value of the
output voltage. This allows you to control the load current or the power in line with the
connected load. The pulse duration can be between 0 (no pulse, always off) and full-scale
deflection (no pulse, always on).
①
②
Pulse width modulation (PWM) is based on the specification of a base frequency of 1, 2, 4, 8
or 16 kHz. You can alter the base frequency in terms of period and pulse-pause ratio over
the control interface (32-bit value). The bit pattern is shown in each base period. The base
period is defined on the basis of the base frequency. A "0" is LOW and a "1" is HIGH.
128
position
Period
Pulse duration
SIMATIC Drive Controller
System Manual, 11/2019, A5E46600094-AA