Digital Input wiring, Electrical Considerations

General installation notes for digital input channels

Digital inputs are activated by making a connection from the input channel to system ground (0V DC):

In practice, several inputs are integrated into one module. The 24V DC supply is used for the internal electronics, and may also be used to power input devices.
An active signal from an Input device must always switch to 0V.
If electronic input devices are used, e.g. inductive sensors, they must be of NPN type.

Digital inputs channels on base module BM 005

A BM 005 is normally used for input functions, because 0V DC is supplied at the terminals.