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Alarm buttons, door sensors, etc.
Alarm buttons, door sensors, ignition, etc. return two states: high or low voltage. Digital inputs
are used to read this information. Figure below shows how to connect alarm button, door sensor, etc.
Figure 10. Panic button connection
In cases when sensor output signal is negative, an additional relay has to be installed to convert
negative signal to positive.
Figure 11. Inverting relay connection
