This logic group implements a pulse width modulation control function, which can be used for a heating system, for example. The control function can be activated and deactivated. The control parameters can be adjusted via separate inputs, the pulse width and ratio via communication object.

The necessary parameters are the "pulse width" and the "ratio".
The "Pulse width" value defines the total duration for one cycle in which the output is switched ON and OFF.
By means of a 0-100% value via the "Ratio" input, the ON and OFF time is determined. This percentage value indicates the time proportion (related to the pulse width) in which the output is switched ON. The remaining time of the pulse duration, the output is set to OFF.

The logic group is started by means of the "Enable" input (with value ON) and operates until Enable is set to OFF. In this case, the current cycle is interrupted and the output is set directly to OFF.
The logic group always starts with ON (value 1) when enabled and ends with OFF (value 0) after the cycle.
In addition, the output can be set permanently to ON with the value 100% for "ratio" and permanently to OFF with 0%. In these two cases, the two TOR elements ("Lock at 100%" and "Lock at 0%") prevent the output value from being changed.
The third TOR element ensures that when the logic group is deactivated, the output is set to OFF and is no longer changed.

Siegl Dominik
SD system integration
(229; 2022.09)