Domoticz module that manages up to 4 energy meters. Also, it has 2 relays, 1 AC input and 2 I/Os

Creasol DomBus34 - Din rail module supporting up to 4 energy meters, 2 relay outputs, 1 AC input, 2 inputs

Energy monitor module with 2 relay outputs, 1 AC input and 2 I/OsDomBus34 is a DIN-RAIL module, 54mm wide, designed to interface up to 4 power/energy meters, type DDS 238-2 ZN/S (Modbus), to measure power and energy (both imported and exported), voltage frequency and power factor.
It implements 2 relay outputs 250V 5A SPST with overvoltage protection, 1 AC input 110-240Vac, and 2 low-voltage inputs that can be connected to pushbuttons and switches, double pushbuttons and counters.

It's designed to activate loads based on power availability, for example when photovoltaic or wind system is producing, and to display nice charts with statistics about energy production/usage with comparisons in a year-by-year basis.

Load switching can be achieved using DCMD commands, but as it works with Domoticz home automation system, it's also easy to make visual and text scripts to do even complex automations.

As other DomBus modules, all ports can be configured in many different ways, and also this module supports DCMD, commands sent to the same or other modules to perform simple actions, that permit to achieve high reliability (DCMD commands work even if domotic controller is not operational) and easy programming (don't need to create automations in the domotic controller, just configure DomBus ports to perform actions on events). Last, but not least, as other DomBus modules, it's optimized to get low power consumption, less than 10mW normally (0.75mA @13.6V) and less than 150mW when all relays are ON (10mA @13.6V).

Domoticz module designed to measure power/energy and switch loads based on power availability


  • 1x RS485 bus to communicate with domotic controller and other DomBus modules
  • 1x RS485 bus to communicate with up to 4 power/energy meters DDS 238-2 ZN/S (Modbus)
  • 2 relay outputs, SPST 250Vac 5A max, with overvoltage protection (varistors)
  • 1 AC input, 110-240Vac, to monitor voltage on loads and detect power outage
  • 2 programmable low-voltage inputs
  • supports DCMD commands, that are used to set outputs on events independetly by the domotic controller
  • 8-25Vdc power supply
  • 10mW power consumption
  • 150mW max power consumption, with both relays ON
  • 52x89x65mm

How to manage one or more energy meters

DDS238-2 ZN/S energy meters are factory programmed with Modbus address = 1. Everytime a new energy meter is connected to the Modbus, its default address should be changed as 2, 3, 4 or 5, by selecting the device M1 Addr and writing in the device Description  ADDR=2 , for example: in this way the energy meter with Modbus addr=1 will be programmed with the new selected address.
Anytime a new energy meter is added, a new set of device will be enabled, displaying the current import and export power/energy, voltage, power factor and frequency.

DCMD commands

*Please check the page in English to get the correct values of commands!

While it's possible to do any automations using the domotic controller features, essential automations can be performed using the DCMD commands that are executed directly by the DomBus module. DCMD commands should be specified in the device description, work even in case that domotic controller is offline and can be sent to the same module itself or to other DomBus modules connected to the same bus.

The syntax is DCMD(Event:ValueLow:ValueHigh)=ModuleAddress.ModulePort:Command:Value

where ValueLow, ValueHigh, Value are optional parameters.

Event Description Example
OFF This even occurs when input (IO1, IO2 or INAC) goes OFF

DCMD(OFF)=3401.1:OFF When input goes off, turns OFF also port 1 of module 3401

DCMD(OFF)=3102.1:OFF When input goes off, turns OFF also port 1 of module 3102

ON This even occurs when input (IO1, IO2 or INAC) goes ON

DCMD(ON)=3401.1:ON:90s When input goes on, turns ON port 1 of module 3401 for 90s

DCMD(ON)=3102.1:ON When input goes on, turns ON port 1 of module 3102

PULSE Input is pulsed ON for less than 0.5s DCMD(Pulse)=13.3:TOGGLE
When input is pulsed shortly, send command to module 13 port 3 to toggle it's output OFF->ON or vice versa
PULSE1 Input is pulsed ON for about 1s

When input is pulsed for 1s, turns ON port 3 of module 13

PULSE2 Input is pulsed ON for about 2s

When input is pulsed for 2s, turns OFF port 3 of module 13

PULSE4 Input is pulsed ON for about 4s

When input is pulsed for 4s, turns ON port 4 of module 13 for 2 hours

VALUE Sensor value is ≥ ValueLow and < ValueHigh
Command is repeated every 30s if the comparison matches.

Turns ON port 31.8 if exported power (from photovoltaic?) is ≥ 1400W, and disable when the exported power falls below 100W

Turns ON port 34.2 if voltage is >= 252V, and turn it OFF if voltage falls below 248V

A possible application of DCMD commands is to enable a load when there is enough exported energy (from solar photovoltaic), and disable it when solar production disappears, or disconnect a photovoltaic string when inverter AC output is too high, and enable it when AC output is normal.

Assuming that the DomBus34 module has address 3401, selecting the Grid Import Energy device and writing in the description field


it's possible to configure the device to automatically enable relay1 when the export power is greater or equal to 1800W (for example to activate a boiler or another load).

Writing the following command on the Grid Import Energy


the DomBus34 module will be configured to disable relay1 when the imported power is greater than 500W. This behaviour is managed internally by the DomBus34 module, and domotic controller will be informed about the state of the Relay1 output.

Similarly, writing the following commands to the the Grid Voltage device

DCMD(Value:252:280)=3401.2:ON, DCMD(Value:0:248)=3401.2:OFF
it's possible to activate relay2 output when the voltage raises to 252V or above, disabling relay2 when voltage falls below 248V: this can be useful during the Summer to avoid inverter disconnections (overvoltage protection) by enabling a load or disconneting a photovoltaic string.

If the output to enable/disable is in another DomBus module, just specify it's address (e.g. 0001.8) and that output will be enabled/disabled based on the current power or voltage value.

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