Microswitches are used to indicate the machine's "home" position.

During startup, the machine moves all 3 axis upwards until the switches are triggered. Triggering this switch tells the machine its initial starting position.

Note the terminal labels:

C (Common)

NO (Normally Open)

NC (Normally Closed)

We wire our end stop cabling to Common and Normally Closed. This means the switch will conduct electricity between these two terminals until the button is pressed. This way, broken wires will show up as a triggered switch press, thus signalling a fault.