SCS is an acronym for "Sistema Cablaggio Semplificato" ("Simplified Wiring System"). It uses a fieldbus network protocol and has applications in the field of home automation and building automation. It is used mainly in bTicino and Legrand installations.
An SCS bus is based on a sheathed twisted pair formed of two flexible conductors; these are braided and unshielded with isolation 300/500V, SELV as double isolation is required – according to the rules adopted by CEI (Italian Electrotechnical Committee). The bus is unpolarized, devices are required to support the DC power supply in both polarity.
Two kind of wiring are possible:
- Free cabling were a mix of bus and star topology are present, better for old houses
- Star wiring were all devices are connected to the switch rack, better for new houses
Across the SCS bus four different types of signals are transmitted in frequency modulation:
- Electricity supply via 27 Vdc
- Data with a frequency clock of 9600 Hz
The transmission protocol is the CSMA/CA.
Through the SCS bus you have the following functions:
- Light control
- Sound diffusion
- Energy management
- Video intercom
- Alarm system
All the listed functions share the same technology and the same procedures for configuration / installation.
All devices connected to SCS bus must be manually configured, no autolearn is possible, apart Alarm system and extenders. Configuration assign an address and an operating mode. Two kind of configurations are possible:
- Physical - using numbered jumpers with different values resistor
- Virtual - using a configuration software connected with an ethernet gateway. In this case the address and operating mode are written in a non volatile memory in every device. Applying a physical jumper override the virtual configuration wiping the memory.
Device addressing use three different 'digits' A|PL|GR. The A mean the room, the PL is the Point of Load in the room, and GR is the group. Group join loads in same or different rooms in a logical manner. Not all devices has group addressing. All devices must answer to room broadcast called AMB. All devices must answer to general broadcast called GEN. Physical and Virtual addressing has different limitations:
|A||1-9||0-10||11 rooms max in a single SCS domain|
|PL||1-9||0-15||A=0,PL=0 is forbidden, so 175 loads are addressable in a single SCS domain|
In big houses and buildings, SCS address extension is possible, were different address domains are connected via some bridges. Only some kind of messages can cross a bridge. Here the values of physical configuration jumpers:
|<empty>||---||infinite||---||default to virtual|
|GEN||blue||? kOhm||3501/GEN||general broadcast|
|GR||blue||? kOhm||3501/GR||group broadcast|
|AMB||blue||? kOhm||3501/AMB||room broadcast|
|AUX||blue||? kOhm||3501/AUX||auxiliary channel|
|ON||blue||? kOhm||3501/ON||send ON command|
|OFF||blue||? kOhm||3501/OFF||send OFF command|
|0/1||blue||? kOhm||3501/01||send toggle command|
|PUL||blue||? kOhm||3501/PUL||button command monostable|
|SLA||blue||? kOhm||3501/SLA||slave of another control|
|CEN||blue||? kOhm||3501/CEN||advanced scenarios mode|
|↑↓||blue||? kOhm||3501/T||up/down for shutters|
|↑↓M||blue||? kOhm||3501/TM||up/down for shutters monostable|
Devices connected to the SCS bus are IMQ-certified and comply with these product standards (International Electrotechnical Commission (IEC) EN 50428 - IEC EN 60669-1/A1 - IEC EN 60669-2-1 - IEC EN 50090-2-2 - IEC EN 50090-2-3 ).
These gateways are bidirectional; they translate SCS frames into OpenWebNet frames, and the other way round. The open protocol OpenWebNet shared by MyOpen community, let everybody to build software that iteract with SCS devices. SCS protocol is a proprietary bTicino protocol. Interaction with other field bus must happen only writing software that use OpenWebNet.