Using a Raspberry Pi for monitoring a Kamstrup Omnipower Electricity Meter. A RPi3 will not work so go with a RPi4 or RPi0W.
The key electricity data we are looking for is Meter status (as seen on the display) and actual total power consumption plus consumption for each phase. Data from the Meter must be converted to readable raw data so it can be used directly by other applications and simply shared with other devices like Home Assistant via UDP or as plain csv files etc.
First of all Push messages need to be enabled from the meter even though the documentation indicates that this is done by default. So contact your power supplier and request push messages and also two keys as the information is encrypted. You will then get a mail from Kamstrup with the keys. It comes in a tabulated setup which will probably be distorted in the mail.
So the message may look like this
| Key | Type | Generation Key |
|---|---|---|
| 64 | 1 | 0x34706890A462483973431E01C8914E21 |
| 65 | 1 | 0x946F0B5C495176089391783F32C4E33A |
The Generation Key is wrong and should be splitted to
| Key | Type | 0x | Generation Key |
|---|---|---|---|
| 64 | 1 | 0x | 34706890A462483973431E01C8914E21 |
| 65 | 1 | 0x | 946F0B5C495176089391783F32C4E33A |
Use the Generation Key for these two keys:
64 = gpk60 = encryption_key
65 = gpk61 = authentication_key
Now connect your RPi serial port to the CCC connector at the Meter like this:
| CCC | RPipin | GPIO | Function (RPi) |
|---|---|---|---|
| 6 | 6 | 6 | GND |
| 2 | 8 | 14 | Data from RPi (Tx) |
| 5 | 10 | 15 | Data from Meter (Rx) |
For a RPi4 the above serial port to use is called ttyS0 when listening to the Meter. GPIO14 is not necessary in this setup but can be used for other applications that makes queries for the Meter.
For listening to the Meter Gurux has a good library that can be installed from https://github.com/Gurux/Gurux.DLMS.Python and they also have an excellent support so sign up at the forum if you have troubles.
When ready you can make a test drive in order to see if the Meter is pushing messages which it should do every 10 sec. Connect to the RPi with SSH and Putty and at the command prompt first change directory to the Gurux listener script:
cd /home/pi/Gurux.DLMS.Python/Gurux.DLMS.Push.Listener.Example.python
Then run the main.py so you can see the options:
python main.py
Now try main.py with addition of the serial port:
python main.py -S ‘/dev/ttyS0:2400:8None1’
Please notice 2400 bps is important. The above should give some initial readings (encrypted) to confirm that the connection is working.
Finally run the application with the encryption keys.
python main.py -S ‘/dev/ttyS0:2400:8None1’ -B 34706890A462483973431E01C8914E21 -A 946F0B5C495176089391783F32C4E33A
You might need to swop -A and -B as encryption_key and authentication_key can be mixed up probably by Kamstrup. You will then see readings presented in different formats. Each Data Object has its own ID as can be seen at page 4 in this list: https://radiuselnet.dk/wp-content/uploads/DLMS-COSEM.pdf
Meter status (as seen on the display) and actual power consumption are all represented by number 14 in the list. You need to convert each number to hex and use space instead of dot. Also leave a space at end, so 1.1.1.8.0.255 gives "01 01 01 08 00 FF " when using it as a condition in Python.
The python script uploaded here (meter.py) is developed thanks to Gurux (see installation notes at end of code)
As the RPi (hopefully) now broadcasts messages at the same network as your HA, you can create a sensor that listens to UDP. As UDP is not supported as a standard HA-component, this can be done instead by creating a sensor that calls a python-script every second. sensor. See configuration.yaml
Then copy content from powernowudp.py etc to HA and make shure the path is correct in configuration.yaml. It's a simple version only showing with current power consumption but you can expand for listening to other attributes in the UDP-string.