This section provides recommendations on wire sizes and lengths for the SMI interface of the RP controller expansion SMI blind modules.
The recommendations are for guidance only. Other wire sizes and lengths may be used, depending on wiring rules and when appropriate.
The connecting cable is a 5-wire cable, which supplies both power and transmits data. The Blind outputs of the SMI high-voltage blind module have five terminals, labeled I+, I-, N, PE, and L, to which the cable is connected. The Blind outputs of the SMI low-voltage (SMI LoVo) blind module have four terminals, labeled I+, I-, 0 V, and 24 V, to which the cable is connected. The connector for SMI LoVo has a 5-pole frame, but only four poles are used in this application.
The maximum total cable length is 350 m, which means that distances of up to 350 m between the SMI blind module and the blind motor are possible.
Wire sizes (cross-sectional areas) from 0.75 mm² (18 AWG) to 2.5 mm² (14 AWG) can be used depending on the following factors:
Total cable length
Minimum voltage required by the blind motor
Rated motor current
Number of blind motors
Because up to 16 blind motors (drives) can be connected in parallel to one SMI blind module (with a maximum of four blind motors per Blind output), you must consider the number of blind motors connected to the SMI blind module when dimensioning the cables. For example, blind motors that operate from mains voltage (230 VAC) can typically handle a maximum voltage reduction of 10% (207 VAC). When several blind motors are connected in parallel to the SMI module, the cables must be dimensioned so that the voltage does not fall below 207 VAC at the last blind motor. For more information, see the SMI Standard Motor Interface website www.standard-motor-interface.com
Only copper wires should be used for the connecting cables.
The cable type should be of the type without screen.