Buses, Protocols and Systems for Home and Building Automation

- Very complex cabling
SMI tries to find solutions for these problems.
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Fig. 3.2.6.2: A basic SMI concept (58)
Standard Motor Interface is a typical monomaster-multislave system where one master is
able to control up to 16 slaves (drives). Slaves can be addressed individually or together
(group addressing or broadcast messages) – the allocation of one address per one drive is
possible, but is not necessary if all the drives are to be controlled together.
There are two types of commands transferred through SMI – standard commands and
manufacturer-specific commands. Commands offer, besides basic actions (e.g. move up,
move down), more complicated and complex actions, for example precise movement to
intermediate position or request for diagnostic/feedback messages (possible responses: a
motor is rotating, direction of the rotation, a motor defect, an actual position). Diagnostic
response is also possible to be read during the drive rotation.
SMI Applications
SMI is specialized only in the intelligent digital operation of drives in buildings. The typical
applications are:
- roller shutters
- sun protection systems
- venetian blind drives
- awning
- solar-operated systems
- swimming pool covers
- winter gardens
- smoke and fire protection
- …
SMI drives can be operated by control units, which can be completely stand-alone (Fig.
3.2.6.3) or are connected to higher building automation systems like KNX or LON for
example (Fig. 3.2.6.4).
Ondřej Nývlt - Buses, Protocols and Systems for Home and Building Automation 39