Compatibility | Power meters with M-bus signal |
Power meter interface |
|
Connection | Wi-Fi 2.4GHz b/g/n |
Power | Powered from the meter during operations. Powered from USB while upgrading firmware. |
Weight | 40 g |
Size | 70 x 39 x 24 mm |
Input voltage | M-bus up to 36V |
Operating power | 0,5 W |
Data encryption | Supported |
MQTT | Internal and external, including SSL |
Home Assistant auto discovery | Yes |
Protection class | IP20 (not waterproof) |
Temperature range | -20°C to +70°C |
Humidity | Non-condensing |
There are (as far as we know!) two different physical interfaces on power meters in Europe that deliver M-bus signal: RJ45 and RJ12.
The M-bus signal is delivered on pins 1 and 2 of an RJ45 socket. The remaining 6 pins are not used.
Base voltage is 24V, dropping to 12V when data bits are transmitted.
Used in Norway, Sweden and Finland(?), this interface is often referred to as HAN-NVE.
The M-bus signal is delivered on pins 3 and 4 of an RJ12 socket. The remaining 4 pins are not used.
Base voltage is around 34V, dropping to 22V when data bits are transmitted.
Used in several Mid-European countries, this interface is often referred to as P1.
Pow-U boards have DIP switch selectors that must be set to ON position when used on Mid-European “P1” power meters:
There are two buttons:
The multicolour LED gives the following indications:
Unlike Pow-K and Pow-P1, the Pow-U does not have pads laid out for easy installation of a temperature sensor.
However, users can install a temperature sensor by exploiting the available GPIO5 that is exposed to a surface pad on the back side of the PCB. Pads delivering 3,3V and GND are also available:
We recommend installing a digital temperature sensor, type Dallas DS18B20, as code supporting this sensor is included in the firmware.
A 4700 ohm resistor is also required.
The sensor should be installed like this:
To activate the temperature sensor, user must change the hardware setting: