Choosing between products

BBQKees Electronics offers two types of 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 around 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 three Gateways model are available:

Although the hardware is a bit different, all models have the identical feature set in the firmware.
The S3 is the basic EMS Gateway.|
The S3-LR is the same device as the S3, but it has an external antenna for locations where the WiFi reception may be poor.
The E32 V2 has, aside from WiFi, an Ethernet/LAN port for wired networking.

All three models are based on the ESP32 range from Espressif. All three have a large 8MB of PSRAM and 16MB of Flash.
The Gateway S3 and S3-LR are based on the ESP32-S3 microcontroller. The E32 V2 has the ‘regular’ ESP32 because that version still supports hardware Ethernet interfaces. This was stripped out of the ESP32-S3.

All three perform similarly. And all three have the exact same EMS bus connection options.

If you have LAN near the boiler or heat pump the E32 V2 would be the best choice.

If you don’t have LAN available near the boiler or heat pump, but good WiFi, the S3 is a good fit, but the E32 V2 also has the same WiFi performance as the S3. Furthermore the S3-LR will also perform well here because of it’s external antenna.

If you don’t have LAN available near the boiler or heat pump, but only poor WiFi the S3-LR could be a good choice. However, you need to check with f.i. your smartphone if there is any WiFi reception at all. If there is no reception, the S3-LR won’t magically find any networks. Only when you have f.i. only one bar of reception on your smartphone the high gain antenna of the S3-LR will help improve the connection over the regular internal antenna of the S3.

Another consideration is the size of the Gateway. The E32 V2 is double the size of the S3 and S3-LR. If you don’t have a lot of room the E32 V2 may be a bit large.

Feature comparison

Below a comparison of the key features and the differences.

FeatureS3S3-LRE32 V2
WiFI 2.4 GHzYesYes (with high gain antenna)Yes
EMS bus service jackYesYesYes
EMS bus screw terminalYesYesYes
USB-C programming portYesYesYes
External power supply 12V DCYesYesYes
Optional DS18B20 sensorsYesYesYes
Wall mountableYes with optional wall mountYes with optional wall mountYes, screw holes on the rear side
Processor architectureESP32-S3ESP32-S3ESP32
RAM memory8MB PSRAM8MB PSRAM8MB PSRAM (firmware uses currently 4MB, but hardware has 8MB).
Flash memory storage16MB16MB16MB
CE certifiedYesYesYes
Dimensions (excluding external connectors)L: 90 mm
W: 50 mm
H: 24 mm
L: 90 mm
W: 50 mm
H: 24 mm
L: 125 mm
W: 85 mm
H: 27 mm
Enclosure constructionVery strong grey ABS plastic with UL 94 V-0 fire retardant classVery strong grey ABS plastic with UL 94 V-0 fire retardant classVery strong white ABS plastic with UL 94 V-0 fire retardant class