Choosing between products

I offer several products to interface with the EMS bus: Gateways and interface boards.

Interface boards are only a pure hardware board that translate the EMS bus signal to a UART serial port signal and vice versa. You need to connect a microcontroller to these boards and install or write your own software to interact with the EMS bus.

Gateways are a complete plug and play package that you can connect to the bus via just one cable or two wires and they provide an easy to use web, MQTT or HTTP interface to communicate with your home automation.

Choosing between a Gateway and an interface board

If you want to have all your boiler and thermostat data into your home automation like Home Assistant, Domoticz etc with only one cable and with only minimal configuration, then pick a Gateway. If you like to play around with electronics, solder stuff and mess arount with Dupont wires, or you want it a bit cheaper but less nice, you can choose one of the interface boards.

Like mentioned above the interface boards are just a piece of hardware. It comes with no microcontroller or software.

Choosing between Gateway models

At this moment there are two Gateway models available:

  • Gateway S32 (Standard edition) = WiFi
  • Gateway E32 (Ethernet version) = WiFi + Ethernet

The Gateway S32 is the next generation model based on the ESP32 microcontroller.
The E32 Ethernet edition has the same features as the S32 but with an additional Ethernet jack for wired networking.

Gateway S32 (Standard edition)

The Gateway S32 (S=Standard edition) is the latest Gateway model based on the ESP32 microcontroller.


  • EMS-ESP firmware version V3 and up
  • Plug-and-play connection to the EMS bus with one cable
  • Connects to the EMS bus via the service jack or the EMS/thermostat wires
  • 2.4GHz Wi-Fi connectivity
  • Complete responsive webinterface
  • Firmware updateable via the webinterface
  • Configured for Home Assistant
  • Supports the Home Assistant MQTT Discovery protocol
  • MQTT Discovery works now as well with recent beta versions of Domoticz.
  • MQTT and Restful API for other interfaces like OpenHAB and Loxone
  • Telnet console
  • Optional DS18B20 temperature sensors
  • Supports all EMS heating circuits
  • Support large EMS systems with many EMS devices simultaneously
  • Support for EMS, EMS+, Heatronic 3 etc.
  • Can be powered via the service jack or a 12V DC adapter.

The Gateway S32 has a lot of room for additional features, which are added regularly.

Gateway E32 (Ethernet edition)

The Gateway E32 has all the same features as the S32 but it has an additional Ethernet jack. So aside from WiFi, you can use the E32 with a wired network.
EMS-ESP is also slighty more responsive using Ethernet.

You can use it with either Ethernet or WiFi.
The E32 has no POE capabilities (as it’s 48V and long wires are dangerous when working with the 16V EMS bus), so it’s powered either via the jack or via a 12V DC power supply.