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DomBus modules use RS485 serial bus to communicate: with a 4 wires shielded cable it's possible to carry both data and 12-24Vdc power supply. RS485 can work with up to 1km of cable, using the terminating 100-150 Ohm resistors on the ends of the bus (the resistor in DomBus module should be enabled, using the PCB jumper, in the two furthest modules).

DomBus modules are really low power consumption, less than 10mW with no outputs active, so it's possible to supply dozens of modules with no problem. Also, DomBus31 module that has 8 relays, consumes only less than 500mW when all relays are ON.

How to design the domotic system

  1. Choose a reliable power supply for the bus: we suggest to use a 13.5V power supply with UPS function (connected to a lead-acid battery). Power supply should be strong enough to supply bus, network switches and routers, IPCams and NVR, ... , so the whole system can work even in case of power outage.
  2. Choose a reliable power supply for the Raspberry PI, if used: the best solution is a a DC/DC converter with Type-C or MicroUSB connector, supplied by the 13.5V power source, so the domotic controller is protected from blackout.
  3. Connect the domotic bus data to a RS485/USB adapter, and supply wires to the 13.5V power supply through a fuse. Use RS485 cables or, alternatively, common alarm shielded cables: 2x0.22mm² for data and 2x0.5mm² for Vbus supply. Connect the shield to GND only on one side.
  4. In any room where you have to measure temperature and humidity, place a DomBusTH module: it is very compact and can be mounted on a blank cover with a 3-4mm hole in the center. It also has red/green leds (that can be used for notifications, like alarm on/off, import/export power, ...), white led (that can be used for notifications and as blackout emergency light), 1x analog input (connected by default to Vbus, to monitor the supply voltage, but can be connected to other voltage up to 30V), 4x I/Os (that can be connected to switches, pushbuttons, dual buttons, buzzer, energy/gas/water meters with pulsed output, alarm sensors, ...) and 2x open-drain outputs (that can be connected to the DomRelay2 module to get 2 relay outputs to command lights, roller shutter motors, appliances, ...).
  5. If you need to interface a gate or garage door, you can use DomBus23 module, that has 2x relay outputs (to send open/close/pedestrian commands), 2x low voltage optoisolated inputs (to be connected to photocell power supply or 12/24V light indicating the gate state), 1x 115/230V optoisolated input (to be connected to 230V flash lamp, if needed to get status from this output, or can be used to monitor power outages). Also, DomBus23 has 1x 12-24V 10A mosfet output (can be used to supply a 12/24V led stripe, with dimming function), 2x analog outputs 0-10V (can be used to regulate the heat pump power, valve, or other appliances with 0-10V input, as like as other led dimming modules), and 2x I/Os.
  6. If you need several inputs for alarm sensors (magnetic contact sensors and PIRs), you can use the compact DomBus12 module that has 7x I/Os (configured as digital inputs, analog inputs, twinbuttons, counters, buzzer outputs, ...) + 2x open-drain outputs (that can be connected to external DomRelay2 module to get 2 relay outputs, or can be configured as digital inputs through PCB jumpers).
  7. If you need several relay outputs, you can use DomBus31 module that has 6x relays with 5A 250V SPST capability and 2x relays with 10A 250V SPDT capability (terminal block with both normally-open and normally-closed outputs).
  8. Any energy, gas or water meter with pulsed output can be connected to DomBus12, DomBus23 or DomBusTH I/Os.
  9. Electric car charging using most energy from photovoltaic? You can use the DomBusTH module with DomRelay2 module to get a very cheap and easy solution to charge the car using the standard EVSE cable (fixed power) that is enabled in a smart way: a script for Domoticz is provided to get a min and max threshold. When battery state of charge is below the min threshold, charge the car anyway (if there is enough power from the grid). Between min and max threshold, use most energy from photovoltaic. Also, it shows on RED/GREEN leds the current imported/exported power from the grid, and on WHITE led the charging power. Also, use a energy meter interfaced to the same DomBusTH module to measure the charging power and energy.

For any questions please contact us by DomBus Telegram group , or by email to This email address is being protected from spambots. You need JavaScript enabled to view it. : your questions and suggestions are really important and let us improve the documentation!

Some application notes

How to supply a domotic system


DomBusTH module used in a bedroom


Domotic system using DomBus23 connected to a garage door or gate Domotic system using DomBus23 to interface 2 to 3 led strips


Domotic system with alarm sensors (PIRs, magnetic contact sensors, ...)


How to control heat pump and ventilation by Domoticz or Home Assistant and DomBus modules


Schema to control heat pump, ventilation, energy meter, temperature and humidity sensors, and much more


Electric vehicle smart charging using Domoticz

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