Connecting a Gateway E32 (ESP32 Ethernet edition)

Gateway connectors

The Gateway E32 has four connectors:

  • RJ45 Ethernet jack

  • 3,5mm EMS service jack connector

  • DC barrel jack connector (5.5/2.1mm)

  • JST connector (3-pin JST 1.5mm ZH)

  • 2022 model: Green screw terminal plug

EMS Bus Gateway E32 connectors

Preferred order of connection

In short this is the best order in which you should try to connect the Gateway:

  • Service jack (If your boiler/heat pump has one).

  • If you have a solar or mixer module with a bus OUT: EMS bus wires on EMS OUT terminal of the module.

  • If you don’t have an external module use the same EMS bus terminal as to which the thermostat is connected or should be connected to.

The service jack provides enough power for the Gateway. In case you use the screw terminal also plug in the DC adapter. You do not need to use the DC adapter when you are using the service jack cable.

Service jack

EMS Bus Gateway on boiler

With the supplied jack cable you can plug in the Gateway to the service jack of the boiler. The entire device is powered via this service jack. So no additional power supply needed. Just the jack cable is all you need. Switch off the boiler or heat pump. First plug in the cable to the Gateway and then into the boiler or heat pump. Press the plug firmly in the connector or both sides. Turn on the boiler or heat pump. If the Gateway is plugged in correctly, it will start blinking slowly to indicate it’s working and looking for the EMS bus and WiFi network.


If you plug in or unplug the jack cable from the Gateway first instead of the boiler side, you may momentarily shortcut the boiler. It will then reboot, which can cause some clicking noises. Nothing to worry about but just unplug the boiler side first.

EMS/thermostat wires

If your boiler does not have a service jack or it does but you want to mount the EMS Bus Gateway elsewhere you can use the additional screw terminal plug to connect to the two EMS bus wires. This can be in parallel with the thermostat or from inside the boiler. You have to use the DC adapter when you are using the screw terminal.

The 2021 model has an external screw termimal plug. First connect the screw terminal plug to the jack cable and then insert it into the Gateway.

Gateway screw connector plug

You need to connect the EMS wires to the left two terminal pins on the terminal plug.

For newer models there is a 2-pin green terminal block on which you can add the ESM bus wires.

On almost all boilers it does not matter which EMS wire you connect to which of these two terminal pins, as the Gateway has an internal correction circuit. However a few boilers and f.i. if you have an RC310 installed the orientation does matter. If installed the wrong way, the display of the thermostat will not show anything. If this is the case, just switch both EMS wires on the Gateway.

You can see here how to locate the correct EMS bus terminals on your boiler: Connecting the Gateway to the boiler side.

Ethernet or WiFi

The Gateway E32 has a RJ45 Ethernet port. You can use it to connect the Gateway to your router with a cable. When Ethernet is active at boot, the WiFi of the Gateway will be turned off. If no Ethernet is found, the AP will turn on.

First boot -> Check the LED

If you plug the Gateway into the boiler or you connect the power plug, the blue LED will start to blink as a sign it has booted and looking for the EMS bus. As soons as it has discovered the EMS bus and your Wi-Fi network, it will light up solid. If the Gateway has already been configured before, the LED will light up solid really quickly after boot, or it will blink slowly. But if it’s new and not connected to your WiFi network yet, it will continue to blink.

If the light is blinking, then go to Connecting the Gateway to your home network. If you don’t see any LED go to Troubleshooting.

During the power-on sequence you’ll see a sequence of LED flashes:

  • 1 flash means the EMS bus is not connected

  • 2 flashes means the network (wifi or ethernet) is not connected

  • 3 flashes means both EMS bus and network are failing. This is a critical error!

A steady light indicates a good connection and EMS data is flowing in. A slow pulse can mean either the WiFi or the EMS bus are not connected yet. A very fast pulse is when the system is booting up and configuring itself which can typically takes a few seconds.