Consolidated Eastron (SDM630,120,72) modbus meter device for Cerbo GX from several sources. See also:
https://community.victronenergy.com/idea/114716/power-meter-lib-for-modbus-rtu-based-meters-from-a.html
No guarantees whatsoever - use at your own risk. If you dare to do so:
.) connect your meter properly via TCP/Modbus or RTU (RS485/Modbus)
.) extract the file venus-data.tgz to the root directory of an USB stick
.) put the USB stick into your Cerbo and do a reboot
.) if you use an USB/RS485 adapter, it may not work the first time (for me it was some default GPS service)
.) in this case you have to run this via a ssh terminal:
# /opt/victronenergy/serial-starter/stop-tty.sh ttyUSB0
# cd /opt/victronenergy/dbus-modbus-client/
# ./dbus-modbus-client.py -s ttyUSB0
then it should detect and set up the meter - wait a bit, then press Ctrl-C to stop the script and run:
# reboot
.) in case of problems, it is easy to roll-back to your previous setup, just
   remove the line "import eastron" (or comment it by preceding a #) from this file:
   /opt/victronenergy/dbus-modbus-client/dbus-modbus-client.py
.) it autodetects RTU/TCP, 9600/19200/38400 Baud, ID 1/2 (otherwise you need adapt
   /opt/victronenergy/dbus-modbus-client/eastron.py for other settings)
.) tested on Rpi 2Z and Cerbo GX with an SDM630 MODBUS v3 (19200 Baud, ID 1) and a Waveshare Industrial USB/RS485 stick