You can use one or more of the IO's as an Input in order to trigger any sequence or event in Neets Project Designer. It might be an external button or switch which enables an event in the controller, like combining two rooms and locking buttons on the slave room.
An input can trigger in two different ways, high or low.
In the schematic below, you can see that the controller accepts voltages up to 24 volts and a short to ground.
The schematic above is the inside and outside of the input circuitry, in many cases you will need a pull-up resistor in order to not have a floating pin (input) because a floating pin is susceptible for electromagnetic influence and therefore you might get unwanted behaviour on the input.
Watch this wikipedia article if you wish to know more about using a pull-up resistor
In the Systems page of Project Designer you assign one of the IO's as an Input as shown below:
Then go to the Feedback section and give the input a function as shown here: