Connecting the Gateway to the boiler¶
Connecting a Gateway to the boiler varies slightly between Gateway editions. There is a difference between the latest Gateway Premium II and all other Gateways.
Each Gateway has the same three connectors:
(left to right)
- EMS bus screw terminal
- 3,5mm EMS service jack connector
- JST connector
Connecting to the boiler (all other Gateways)¶
Main method - service jack¶
With the supplied jack cable you can plug in the gateway to the service jack of the boiler. This is usually located on the front. Then stick the gateway to the metal side of the boiler. The underside of the case is magnetic. The entire device including the Wemos is powered via this service jack. So no additional power supply needed. Just the jack cable is all you need. It’s important that you first plug in the cable to the gateway and then into the boiler. Otherwise you momentarily shortcut the bus when inserting the cable into the jack of the gateway.
Alternative method - 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 screw terminal to connect to the two EMS bus wires. This can be in parallel with the thermostat or from inside the boiler. In this case you can’t use the buck voltage converter. You need to power the device by plugging in a USB power supply directly to the Wemos.
If you have a Premium Gateway with a Lolin Wemos V3, you need to remove the plastic tabs on the bottom side of the Wemos so the USB connector of the Wemos will be accessible from the side with the top case attached. If you have a Gateway Regular, the USB connector on the Wemos V2 is already accessible. So you don’t have to remove the tabs.
First boot -> Check the LED¶
If you plug the gateway into the boiler, the on-board LED of the Wemos will start blinking fast for the first few seconds. Then it will start to blink slow as a sign its looking for the EMS bus. As soons as it has discovered the EMS bus, it will light up solid. If the Gateway has already been configured before, the LED will light up solid really quickly after boot.