This reposicoty contains the Venus OS system service to make the Peacefair PZEM-016 and PZEM-017 data available on Venus OS and VRM.

The primary use case is to monitor the Victron MultiPlus AC input and output to get energy consumption. newer MultiPlus have this built-in but older versions don't. This data is necessary to know how much you consumed energy from your solar panels or from the grid.

Secondary use case is to make use of the DC meter to monitor additional DC battery chargers on the system, such as a wind turbine charger. This part is not yet fully done.

• finish pzem service calculation MockMultiplus and put in separate service
• finish service to save energy timeseries
• service to display enery timeseries

The PZEM devices are set up on the system to monitor the MultiPlus AC input and AC output. They are connected to an RS-485 bus, which is connected to the master device, an RS-485 USB device that is made available on linux as a ttyUSB device. On top of RS-485, it's talking using the Modbus-RTU protocol.

For some reason, I could not make the device connect on the same bus, and I had to connect a single PZEM device to a single USB dongle.

On VenusOS, the serial-starter service monitors serial devices connected to the board, and spawn a pzem service per serial device. This is thanks to the configuration file in /data/conf/serial-starter.d/pzem-usb.conf.

The pzem service will talk to the PZEM devices using modbus-rtu and export the information to the dBus system bus. This is automatically recognized as a sensor and integrated in Venus/VRM.

It takes two PZEM-016 (AC meters), one is connected to AcIn1 and the other to AcOut ports of the MultiPlus. All the reports goes to:

• fr.mildred.pzemvictron2020.pzem016.tty*-*/Ac/Current
• fr.mildred.pzemvictron2020.pzem016.tty*-*/Ac/EnergyTotal
• fr.mildred.pzemvictron2020.pzem016.tty*-*/Ac/Power
• fr.mildred.pzemvictron2020.pzem016.tty*-*/Ac/Voltage
• fr.mildred.pzemvictron2020.pzem016.tty*-*/Ac/Frequency
• fr.mildred.pzemvictron2020.pzem016.tty*-*/Ac/PowerFactor
• fr.mildred.pzemvictron2020.pzem016.tty*-*/ErrorCode
• fr.mildred.pzemvictron2020.pzem016.tty*-*/ErrorMessage
• fr.mildred.pzemvictron2020.pzem016.tty*-*/DeviceAddress
• fr.mildred.pzemvictron2020.pzem016.tty*-*/DeviceModel

You need a BMV-700 too with:

• com.victronenergy.battery.*/History/ChargedEnergy
• com.victronenergy.battery.*/History/DischargedEnergy

It will measure energy and report a com.victronenergy.vebus bus name using:

• com.victronenergy.vebus.*/Energy/InverterToAcOut(t) = com.victronenergy.battery.*/History/DischargedEnergy(t)
• com.victronenergy.vebus.*/Energy/AcIn1ToAcOut(dt) = fr.mildred.pzemvictron2020.pzem016.ACOut/Ac/EnergyTotal(dt) - com.victronenergy.battery.*/History/DischargedEnergy(dt)
• com.victronenergy.vebus.*/Energy/AcIn1ToInverter(dt) = fr.mildred.pzemvictron2020.pzem016.ACIn1/Ac/EnergyTotal(dt) - com.victronenergy.vebus.*/Energy/AcIn1ToAcOut(dt)

Notation:

• metric(t): metric at time of computation
• metric(t-1): metric as it was last computation
• metric(dt) = metric(t) - metric(t-1)

It assumes that energy coming out of the battery is always going to AcOut through the inverter. In case the VenusOS is not working, metrics are lost for that time (unless the t-1 metrics are stored on disk).

Copy the data directory over the data directory on your VenusOS device, then run rcS.local to install the files not belonging to /data in the right place. See deploy.sh.

PZEM devices have in persistent memory a modbus address which is by default 1. You can use the tool in data/pzem/pzem-info.py to query that information and change this address. To have this working, a single device must be connected to the RS-485 bus at a time.

mapping from Modbus slave address and the sensor kind is done statically in data/pzem/pzem-dbus.py at the end of the file:

DbusPzemService(
    tty=opts.device,
    devices={
        10: "inverter0",
        20: "inverter",
    })

This means that device at address 10 is to be declared in Venus as the port 0 of an inverter (1st AC input of a MultiPlus). And the device at address 20 is to be declared as default port of an inverter (port 1, AC output of a MultiPlus).

Quick feedback loop:

• edit source code
• push your code: ./deploy.sh
• test your code on VenusOS: /data/pzem/pzem-dbus.py -d /dev/ttyUSBx

Useful commands:

• dBus introspection: dbus --system [BUS_NAME [OBJECT_PATH [METHOD]]]
• device introspection: udevadm info /dev/ttyUSB0 (to find the USB device that is not vendored by Victron, for me that's the RS485 adapter)
• service management: cd /service/.../
  • bring up: svc -u
  • bring down: svc -d

• PZEM-016 and PZEM-017 manuals are available as PDF scans here.
• Get root on Venus: https://www.victronenergy.com/live/ccgx:root_access
• Driver implem: https://github.com/victronenergy/venus/wiki/howto-add-a-driver-to-Venus
• Data structure: https://github.com/victronenergy/venus/wiki/dbus#vebus-systems-multis-quattros-inverters
  • com.victronenergy.grid
  • com.victronenergy.pvinverter
  • com.victronenergy.battery
  • com.victronenergy.vebus
• Get permission on tty for devloppment: sudo setfacl -R -m u:$USER:rwx /dev/ttyUSB*
• Nim: https://nim-lang.org/
• javascript charts: http://gionkunz.github.io/chartist-js
• timeseries logging:
  • http://discretelogics.com/doc/teafiles.py/teafiles.html
  • https://github.com/unicredit/nim-teafiles

• Python 2.7
• pyserial (pip2 install pyserial==3.4)
• pymodbus (pip2 install pymodbus==1.3.2)
• BMV-700 firmware at least 3.08: Fixed issue with Charged/Discharged Energy & Cumulative Ah (aka Total Ah Drawn) counters: the counters could get stuck at a certain value and become 'insensitive' for (small) changes