Axpert Python Log Script

This is a set of functions for logging the Axpert inverter measured data to a text file format.

This data can then be analyzed off-line.

Installation

The following steps must be followed in order to install the functions:

The installation is tested on a Raspberry Pi with Raspbian, but should work with some other Linux flavours as well.

• clone the the following repository in a home folder:

  git clone https://github.com/Interster/AxpertInverterLogScriptPython.git

• install crcmod for python3

  sudo pip3 install crcmod

• create rules for the Axpert/Voltronic inverter

  echo 'ATTRS{idVendor}=="0665", ATTRS{idProduct}=="5161", SUBSYSTEMS=="usb", ACTION=="add", MODE="0666", GROUP="root", SYMLINK+="hidVoltronic"' > /etc/udev/rules.d/35-voltronic.rules

• add a time for the logging to begin automatically by editing the cron table and by typing the following in a terminal

  crontab -e

  Then add the following line to the crontable (This starts logging a 24 hour cycle at 00:00 at night):

  0 0 * * * python3 /home/AxpertInverterLogScript/AxpertInverterLogScriptPython/LogAxpert.py

  Remember to make sure that your path is correct.

This is a Hassio addon to monitor voltronic axpert inverters through USB and publish the data as JSON to an MQTT broker. It publishes the data to 2 topics:

• 'power/axpert' for the parallel data (some of these values seem to be only for the connected inverter even though they are returned by the parallel data command)
• 'power/axpert{sn}' for the data from the connected inverter (configurable, {sn} is replaced with the serial number of the inverter)

You can then configure the sensors in Home Assistant like this:

sensors:
  - platform: mqtt
    name: "Power"
    state_topic: "power/axpert"
    unit_of_measurement: 'W'
    value_template: "{{ value_json.TotalAcOutputActivePower }}"
    expire_after: 60

The values published on 'power/axpert' are:

• SerialNumber # of the first inverter in the parallel setup
• TotalAcOutputActivePower
• TotalAcOutputApparentPower
• TotalAcOutputPercentage
• BatteryChargingCurrent
• BatteryDischargeCurrent
• TotalChargingCurrent
• GridVoltage
• GridFrequency
• OutputVoltage
• OutputFrequency
• OutputAparentPower
• OutputActivePower
• LoadPercentage
• BatteryVoltage
• BatteryCapacity
• PvInputVoltage
• OutputMode
• ChargerSourcePriority
• MaxChargeCurrent
• MaxChargerRange
• MaxAcChargerCurrent
• PvInputCurrentForBattery
• Gridmode
• Solarmode

The values published on 'power/axpert{sn}' are:

• BusVoltage
• InverterHeatsinkTemperature
• BatteryVoltageFromScc
• PvInputCurrent
• PvInputVoltage
• PvInputPower
• BatteryChargingCurrent
• BatteryDischargeCurrent
• DeviceStatus

I have 3 inverters in parallel and a raspberry connected to 1 of them with a USB cable . Linux doesn't seem to recognize it as a USB to Serial device and it only shows up as /dev/hidraw0.

A description of the serial communication protocol can be found here

Rules for the HIDRAW device

Devices from Voltronic are shipped with 4 possible hardware interfaces: RS232, USB, Bluetooth & RS485

All the interfaces share the same underlying communication protocol

The Axpert is an HIDRAW device. It requires the following rule to set up in order to give the active user to access the device:

echo 'ATTRS{idVendor}=="0665", ATTRS{idProduct}=="5161", SUBSYSTEMS=="usb", ACTION=="add", MODE="0666", GROUP="root", SYMLINK+="hidVoltronic"' > /etc/udev/rules.d/35-voltronic.rules

This command requires root access. On a raspberry pi use the command:

sudo su

and then echo the contents to the udev rule file.

Simultaneous communication across multiple interfaces

During testing it was found that simultaneous communication across USB & RS232 for example would result in device lockup. The device keeps operating, but the device will no longer respond to input or produce output.

As such it is advised to pick an interface and use it exclusively.

An example of this is trying to communicate simultaneously to a Pylontech battery and an Axpert inverter. Lockup will occur and then neither device will respond.

Protocol

This section is heavily borrowed from

https://github.com/jvandervyver/libvoltronic

Communication protocol

The communication protocol consists of the following format:

Overall the protocol has the following format:

{bytes}{CRC16}{end of input character}

• bytes the actual bytes being sent to the device, generally speaking this is the "command"
• CRC16 common CRC protocol with many implementations online
• end of input character character signaling the end of input

Reserved characters

These characters are reserved

• \r (0x0d) End of input character
• ( (0x28) Seems to indicate start of input
• \n (0x0a) No material importance but still reserved

Bytes

The bytes being sent to the device appear to be simply ASCII in the form of a command

Multiple documents exist listing possible commands

• Axpert
• Infini Solar

CRC

The CRC is used is the CRC16 XMODEM variation

Background

Multiple methods exist to generate CRC.

CRC16 as the name implies contains 16 bits or 2 bytes of data. It is commonly written as hexadecimal for readability reason, ie> 0x17AD

Two hexadecimal character represent a single byte so given the example above. 0x part simply indicates hexadecimal 0x17 is the first byte 0xAD is the second byte

Exception

The Reserved characters are not allowed in the CRC. It appears the device simply expects them to be incremented by 1

So 0x28 becomes 0x29, 0x0d becomes 0x0e, etc.

End of input character

The \r character signals to the device end of input

Regardless of what the device received up to that point \r signals to the device end of current input

Once this character is received all input up to that point is taken as the command to the device

Gebruik van MQTTT

Geleidelike ontwikkeling het getoon dat MQTT heel moontlik die beste rigting is om die Axpert log sagteware te benut.

Hier volg die beskrywing die installasie van 'n broker (die diens) en kliënt van Mosquitto MQT

Verder word die gebruik binne die kode ook beskryf.

Installasie van MQTT op raspberry pi

Hierdie beskrywing leen baie uit die volgende webbladsy:

http://www.steves-internet-guide.com/install-mosquitto-linux/

Installeer Mosquitto MQTT op die raspberry pi met die volgende opdrag:

sudo apt-get install mosquitto

Begin die diens of "broker" met die volgende opdrag:

stop die broker met die volgende opdrag

sudo service mosquitto stop

en begin dit met die volgende opdrag:

sudo service mosquitto start

Die volgende opdrag kry die weergawe van mosquitto, maar jy moet die broker eers staak voor jy dit uitvoer:

mosquitto -v

Toets of die installasie werk deur die volgende opdrag te gebruik:

netstat -at	

Jy behoort die Mosquitto broker te sien loop op port 1883:

Maak ook seker dat die paho-mqtt client installeer is op die raspberry pi met die volgende opdrag:

sudo pip3 install paho-mqtt