Magnum 2 MQTT

A tool for monitoring a Magnum inverter using Python3 and a RS-485 to serial converter, then publishing that data to an MQTT broker.

Credits

Prior work in this arena from:

• Chris (aka user cpfl) Midnightsolar forum.
• Paul Alting van Geusau
• Liam O'Brien

Backstory

Code from earlier versions of the repostiory based heavily on work by Liam O'Brien and others noted above.

This version is a complete rewrite:

• Now uses a protocol definition file and interpreter model.
• Changed the Serial data collection to provide better synchronization to the on-the-wire protocol
• Moved the Serial collection a separate thread.
• Added better 'junk' packet rejection.

Known issues

• For the PT-100, the documented mode and regulation ( Accessory segment 0xC1, byte 2 ) does not follow observed data.
• ACLD Remote packet ( remote 0xD0 ) is not documented in the spec PDF file I have, thus not provided for in the spec file.

Usage

• Copy files from /etc and /usr to system with an RS-485 serial converter.
• Reload the systemd daemon:

  # systemctl daemon-reload
  

• Modify options in /etc/default/magpi for MQTT broker and rentention based on command line options:

  # ./magpi.v3.py  --help
  usage: magpi.v3.py [-h] [-b BROKER] [-d {0,1,2}] [-i INTERVAL] [-p PORT] [-r]
                     [-s SPECFILE] [-t TOPIC]
  
  optional arguments:
    -h, --help            show this help message and exit
    -b BROKER, --broker BROKER
                          MQTT Broker to publish to
    -d {0,1,2}, --debug {0,1,2}
                          debug data
    -i INTERVAL, --interval INTERVAL
                          MQTT update interval ( default 1 second )
    -p PORT, --port PORT  commuications port descriptor, e.g /dev/ttyUSB0 or
                          COM1
    -r, --retain          MQTT Retain?
    -s SPECFILE, --specfile SPECFILE
                          Magnum Protocol Spec File
    -t TOPIC, --topic TOPIC
                          MQTT topic prefix
  

• Enable & Start the service, specifying the proper RS-485 serial device ( e.g. ttyUSB0 )

  # systemctl enable --now magpi@ttyUSB0
  

Inverter Remote / Network port pinout:

Holding a 6 Pin RJ-11 connector with the tab facing away from you, cable dropping out of that connector toward you, here is the pin-out from left to right:

• 1 = NC
• 2 = (A+ 0-5V)
• 3 = (GND)
• 4 = NC
• 5 = (B- 7-12V)
• 6 = (14V w/respect to 3 as GND)

NOTE: Magnum cautions that Pin 6 voltage should NOT be used to power any accessories.