Lighting control system configuration
In the lighting control system, every device hangs on a single RS485 line. The modules in the dimmer panel, the switches in each room, input modules that receive sensors, the setup PC and HA (home automation) all exchange ASCII commands on the same line. This page explains, with a diagram per circuit, how each module and switch is connected.
Overall configuration diagram
Inside the dimmer panel the modules are connected by RS485, and that line leaves the panel and extends to switches and sensors, the setup PC / HA and other dimmer panels. Select a circuit to highlight only its wiring and show its description.
Communication specification
Since all communication is RS485, the system is best understood as an “RS485 platform”. The protocol is ASCII without handshaking. Most HA equipment supports external RS485 devices, so it can be connected to the line as is and send commands.
| Standard | EIA RS-485 |
|---|---|
| Circuit type | 2-wire, half-duplex (transmit and receive switch on the same pair) |
| Topology | 1:N multi-master (any node can transmit) |
| Synchronization | Asynchronous (start-stop) |
| Communication parameters | 9600bps / data length 8bit / parity none / stop bits 1 |
| Nodes | Up to 32 RS485 transceivers per line. Split with a router if exceeded |
| Collision avoidance | Before transmitting, check the receive buffer; if another node is transmitting, wait 5 ms + a random 0–10 ms and retry. No special protocol is required on the HA side |
| Cable | FCPEV-S 0.6 mm or 0.9 mm, 2P (between panels) / 3P (switch circuit). Always pair A and B on one twisted pair |
Cables and terminals
Each circuit uses a specific cable. Only the switch circuit carries, in addition to the RS485 signals, the DC 12 V that powers the switches on the same cable.
FCPEV-S 3P
Daisy-chain wiring panel → switch → switch → input module. Signals A and B, signal ground (SG) and DC 12 V power are each assigned one pair. Grounding the shield is recommended.
FCPEV-S 2P
Between dimmer panels, and to the HA and setup PC. No power is sent between panels, so only signals A and B, SG and the shield.
FCPEV-S 1P
Between the input module and sensors / relays. The module's 3.3 V passes through a dry a-contact and returns to an Input terminal.
KIV 0.5 or larger (red / blue)
From the dimmer panel to the remote-control relays in an external panel. Blue is the common wire permanently connected to the remote-control transformer; current on red switches each relay.
VVF / Canare
From the terminal blocks at the top of the dimmer panel to the lighting fixtures. VVF for the power of phase-dimming, ON/OFF and PWM fixtures; FCPEV 1P for the PWM dimming signal; Canare DMX cable for DMX.
Terminals: 3.5 mm pitch, push-in type (spring cage), solid wire 0.5–1.0 mm², mating at 45° to the board. The IN and OUT sides are connected on the board, so the daisy-chain wiring continues directly to the next switch.
| Terminal label | Signal | Wire color |
|---|---|---|
+ / − | DC 12 V for switches (switch circuit terminal block only) | Yellow / white |
A | RS485 signal A | Blue |
B | RS485 signal B | White (blue pair) |
G | Signal ground (SG) | Green / white |
E | Shield (drain wire) | — |
The panel terminal blocks are separated by circuit (inter-panel communication ABGE ABGE, HA communication ABG, switch communication +−ABGGE, etc.). Keep yellow/white, blue/white and green/white as pairs, and always connect the shield drain wire to E.
Switch configuration
A switch is a plate with a row of rotary encoder knobs that can be turned and pushed. Each plate has an address (plate number), and each knob has a button number and a group number; a knob operates the lighting circuits with the same group number.
3 knobs = main board only, 5 knobs = 1 extension, 7 knobs = 2 extensions. Extension boards connect by FFC (16-pole, 0.5 mm pitch, 35–40 mm, top contacts on both ends).
| Plate number | Address of each switch. Specified in commands as b001… |
|---|---|
| Button number | Numbers 1–7 for the knobs on the plate (from the top) |
| Group number | One of 000–999 for each knob. Each lighting circuit stores the groups it belongs to and is operated by knobs with the same number |
| Rotate | Right for UP, left for DOWN. Stops at the module's upper and lower limits; turning does not switch off |
| Push | ON/OFF. The dimming % at OFF is saved in the module's EEPROM and restored at the next ON (kept through power failures) |
| Operating mode | onof(ON/OFF toggle) / scns (scene recall) / na__ (no action). For a knob used as a scene button, turn its encoder OFF |
| Setup | Connect a PC to the RS485 line and set up with commands in terminal software (Excel is not supported). Initial settings: number of buttons bxxxwvol, encoder ON/OFF bxxxency, mode bxxxmode |
| Hardware | ARM SoC (firmware updatable), isolated RS485 driver, DC 12 V input, LEDs showing knob status |
Example: put all lighting circuits of the living room in group 005 and set a knob's group to 005 as well; that single knob then operates UP/DOWN/ON/OFF for the whole living room. The reference board is ROTARY03 + ROTARY02N.
Input module
Monitors dry a-contacts such as occupancy sensors, elevator arrival signals and light sensors (EE switches), and sends contact changes as commands to RS485. It is daisy-chained on the same circuit as the switches and also takes its power from the communication cable.
When the voltage from 3.3V Out returns to Input through the external relay contact, it is detected as “on”. The input stage is isolated by optoisolators.
| Terminal | Description |
|---|---|
3.3V Out ×2 | Voltage output for dry a-contacts. Returned to Input through a relay |
Input1–4 | Input of the voltage returned from the contact (4 channels) |
RS485 A ISO / B ISO | Isolated RS485 terminals |
0V ISO | Signal GND (SG) of the isolated RS485 |
Earth | Shield |
DC12V / POWER GND | Plus / minus of DC 12 V received from the switch circuit |
| Daisy-chain wiring | Branch with a joint fitting outside the terminal block, or joint at the terminal block |
| Location | Near the sensor. Depending on the building, in the attic space etc. |
| Setup | No setup over RS485; the behavior is fixed in the firmware (direct connection to HA is also possible) |
Mechanical relays are standard. When using an occupancy sensor for 100 VAC loads, insert an AC relay with a 100 VAC coil as a buffer. Solid-state relays only if matching tests can be performed.
Command flow
A switch sends only “which group, and what to do”. Every module receives the command and acts only if its circuit belongs to that group. This is why area-by-area operation is possible with a single cable.
Turn the knob one notch to the right
Turn the knob assigned to group 005.
Transmit to RS485
v005up__ These 8 characters travel over the whole line.
All modules receive
Each circuit checks its group table.
Only matching circuits act
Only the circuits of group 005 raise their brightness one step (up to the upper limit).
| Command | Example | Length | Action |
|---|---|---|---|
| UP | v001up__ | 8 | Brighten the circuits of group 001 by one step. Sent when the knob is turned one notch right |
| DOWN | v001down | 8 | Dim the circuits of group 001 by one step (stops at the lower limit). Knob turned one notch left |
| ON | v001on__ | 8 | Turn on at the dimming % saved last |
| OFF | v001off_ | 8 | Save the current dimming % and turn off |
| Scene call | g001sccc0005 | 12 | Recall the dimming % of scene 5 in the scene table for each circuit of group 001 |
| Fade | g001fade0010 | 12 | Set the fade time for scene calls to 1.0 s (kept in EEPROM). Sent just before a scene call |
Sensors, input modules and HA send the same commands. The 8-character “v command” is a short message intended for continuous transmission from rotary encoders; at 9600 bps it takes about 7 ms, and a 12-character command about 10 ms.
Wiring notes
Most causes of unstable communication are in the wiring. Check the following points during installation.
- Wire as a daisy chain. Connect switches and sensors from the panel with a single daisy-chained cable; do not branch in a star.
- Always put A and B on one twisted pair. It is balanced transmission, so splitting them across different pairs loses the RS485 characteristics.
- Do not bundle with power lines. Routing together with power lines such as 100 VAC, or routing outdoors, causes noise.
- Ground the shield. The shield has no effect unless the drain wire is connected to terminal E.
- Use a router beyond 32 devices. One line supports up to 32 transceivers. Also add a router to split the line when inter-panel communication is unstable.
- Allow margin for inrush current on task circuits. Remote-control relays handle up to 20 A, but allow capacity margin for the inrush current of LED fixtures.
Source: Lighting control system specification Rev03 (Ch. 1 System, Ch. 5 Switches, Ch. 6 Input module, Ch. 7 Drawings). The specification lists the ON/OFF module as RELAYX4; the current reference board is RELAYX8.