Powering of modules

Most of the types. e.g. M4xx, M200, M560 a M710 have the signal part separated from the power part by a DC/DC converter and optotransistors. This means that the signal ground is completely separated from the power part and it is possible to connect the signal ground to power supply ground, and use three-wire connection.

As some modules are able to process low voltage (relays, 230 V AC inputs), the communication part is separated as well to increase safety.

(The thick grey line represents internal galvanical separation of the module parts.)


Some analogue input (M500) and output (M6xx) modules have also the power and signal parts separated. Communication is not separated from the power part. However, it is possible to use three-wire connection here as well.


The MCIO2, MMIO and MXIO compact modules have all internal parts (power – analogue inputs – analogue outputs – binary inputs – binary outputs – communication) separated from each other. Note that if active sensors are connected with 0…10 V output, the AIGND ground must be connected to the G0 (24 V AC ground) so that the sensor output signal has a reference potential. The same applies for analogue outputs: when the valves and damper actuators use three-wire connection (G, Y, G0) the AOGND terminal must be connected to G0.

In general, it is recommended to use a separate transformer for supplying of the peripherials at larger installations.