PWM OUTPUT (PWM)

PWM (Pulse Width Modulation) Output

The solid state digital and PWM outputs are only available on controllers with a DC voltage supply indicated by S XX VDC. The output units which supply a PWM signal (O1 - O4 for types 12 and O1 - O6 for types 20) can also supply a solid state digital type signal (DO). The selection is made by the programmer, who can place one of the two symbols accessible in the OUT tab of the function bar on the unit.

The input (internal controller input) of the PWM output is an integer value. The value of an integer at the output of an FBD function block can be between -32767 and +32767. The PWM only takes into account values between 0 and 255: this means that all input values less than 0 are reset to 0 and that all values greater than 255 are reset to 255. This value between 0 and 255 is used in the PWM to vary the cyclic ratio of a digital clock. For example:

The maximum supply voltage of the PWM output is 30 Volts.

In Simulation and Monitoring modes, the digital value at the input of the PWM output is displayed.

The frequency of the digital clock which controls all the PWM outputs on one controller can be selected by clicking on the PROGRAM box above the background of the edit window.

The frequency can be selected from one of 16 possible values between 113 Hz and 1807 Hz. The default PWM pilot frequency is 1807 Hz.

Parameterisation box/Comments tab

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