SMI technology

The SMI interface defines a standard and robust link between roller shutter/venetian blind drives and control units. Low cost but effective interface circuits are built into the SMI drive and the SMI control unit. These match up to the building’s demanding requirements.

SMI drives have 5-core leads. Three cores are for the power supply and the earthing (L, N and PE) and two cores are for the data transfer. The data transfer is so robust that no special types of leads are required. In addition the power supply and the data transfer (I+ and I-) can coexist in the same lead.

The data signal leads are protected against any polarity reversal so that no incorrect connection can destroy a drive. The input circuit is protected against overvoltage so that no destruction is possible if high interference voltages occur.

Thanks to the ingenious SMI circuit interface, lead lengths of up to 350 m can be accommodated. This means there are virtually no limitations that have to be taken into account during the planning.

Data signal transfers take place at 2,400 bits per second. Together with the very efficient standard commands this ensures fast response times.

A parallel connection of up to 16 drives to the same motor control unit is possible. Thanks to a global addressing it is possible to have just one start-up in a wired system.

The drives can be addressed together or individually, i.e. the allocation of one address per drive is possible, but is not necessary if all the drives are to be controlled together.