Basic properties

All modules are powered by 24 V AC, unless stated otherwise. As the module power supply contains a 2-way rectifier (Graetz bridge), the microprocessor will also work at 24 V DC, however, some outputs (e.g. triacs) require alternating current. It is thus better to keep the same power voltage across the system. The power terminals are marked Gand G0. Module consumption is about 1 VA depending on module type and status of the relays, maximum consumptions for power supply dimensioning are stated in the module data sheets.

The bus communication is connected to terminals K+and K-. The RS485 is a 2-wire bus, polarity must be kept. Communication baudrate is selectable in the range of 1200 to 115200 bps, the higher value may be lower at older module types. Default factory setting is 9600 bps, which is also the recommended baudrate for normal usage.


To connect all the signals and power, removable screw terminals are used. This makes installation and service easy. The modules are snapped on a DIN rail. Most of the modules have width of 4 or 6 DIN units, see data sheets for detailed dimension description.

At the front side of the module there is a label with module name and indication LEDs. All modules have two LEDs indicating power and bus communication (transmitting), more LEDs are on modules with binary inputs and outputs to indicate states of the datapoints.

Close to the communication terminals there are switches for bus termination and initialisation. Most of the I/O modules can be addressed either using DIP switches, or software – a free program ModComTool.