What SCS is
SCS (Simplified Cabling System) is the two-wire bus on which BTicino's MyHOME system (Legrand group) is based. The same two wires carry both data and power for the devices. It is used for lighting, blinds, heating control, scenes and video door entry. It is a proprietary system, not an open standard like KNX. Devices are compatible within the maker's range.
Cable
The bus is a twisted pair without polarity: the two wires can be connected in either order. The bus is powered at about 27 V DC from a dedicated power supply. Topology is free: star, tree or bus, with no terminators needed. This simplifies repairs and changes, but the length and total consumption of a line have limits stated in the maker's documentation.
Addressing with configurators
Devices are not programmed with software as in KNX. Each gets its role and address through configurators: small plugs in sockets on the device. They set the room (A), the point number (PL) and the operating mode. Two devices with matching configurators work together, for example a switch and a lighting actuator.
What is controlled
- Lighting: on/off, dimming, groups and scenes.
- Blinds and roller shutters.
- Heating control: zones, probes, control unit.
- Video door entry and sound distribution.
Connecting external systems
For control from a smartphone, an automation server or another system, a gateway (for example a MyHOME web server) translates the bus to the IP network. The protocol is called OpenWebNet. It is text-based: commands are strings with asterisks and hash signs, for example to switch a lighting point on. Home Assistant and other systems can control MyHOME through it. Gateways accept TCP connections and access is protected with a password. The exact parameters (port, authentication format) come from the documentation of the specific gateway.
When it fits
- Homes where MyHOME is already installed.
- Sites that need quick installation without software configuration.
The limitations are dependence on one maker and less flexibility than open systems.
