Electrical Considerations

General installation notes for output channels (current sink output):

Digital outputs are designed for 24VDC operation. The basic function of a digital output can be compared to that of a relay:

In practice, several outputs are integrated into one module. The 24V DC supply is used for the internal electronics as well as the supply of the connected devices.

Each channel has its own overload protection circuit. The module has to be protected by an external fuse in the supply wire.

Digital output channels on base module BM 006 with 6 outputs

A BM 006 is normally used for output functions, because 24V DC is supplied at the terminals.

If external 0V DC connections are made, channels 1 to 4 could also be used as inputs.

General installationnotes 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.

If external 24V DC connections are made, channels 1 to 4 could also be used as outputs.

Using a PD 621 on base module BM 004 with 2 x relay outputs and 4 inputs

The two internal relays are connected to channels 5 and 6, which must be configured as outputs.

Channels 1 to 4 are normally used as inputs, because 0V terminals are available. If external 24V DC connections are made, channels 1 to 4 could also be used as outputs. (Please refer to drawings for using mixed inputs / outputs on BM 005 / BM 006 base modules)