Siemens SIMATIC S7-1500 Manual page 15

Product overview
2.2 Functions
How it works
In the pulse width modulation mode, the two outputs (channels 0 and 4) provide one pulse
width modulated output signal.
Pulse width modulation is characterized by its time period (frequency) and its duty factor
(also referred to as ON period or Duty Cycle ). The duty factor describes the relation
between pulse duration and time period.
The pulse duration is derived from the time period and the duty factor: Pulse duration = duty
factor x time period.
Example for duty factor of 50% and time period of 10 ms:
Pulse duration 0.5 x 10 ms = 5 ms
You define the duty factor for channels 0 and 4 in the user program using the output value
(0 ... 1000) in the process image output; see section Address space operating mode pulse-
width modulation (Page 29).
The output signal is a square wave signal (pulse sequence of on and off pulses).
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Figure 2-2
Minimum pulse duration
The minimum pulse duration is 300 μs due to the hardware. The duty factor can be adjusted
from 0.0 to 100.0%. The time period can be adjusted from 2 to 100 ms.
Example: If you configure a time period of 2 ms and set a duty factor of 10% for the output,
this results in a pulse duration of 200 μs. In fact, the output works with a minimum pulse
duration of 300 μs.
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Time period T (2 to 100 ms); Frequency of the pulse width modulation: f = 1/T (10 to 500 Hz)
Pulse duration (duty factor x time period)
How pulse width modulation works
DQ 8x24VDC/2A HF Digital Output Module (6ES7522-1BF00-0AB0)
Manual, 06/2018, A5E03485650-AF