modbus4mqtt 0.1.3

A YAML-defined bidirectional Modbus to MQTT interface

Modbus4MQTT

https://github.com/tjhowse/modbus4mqtt

This is a gateway that translates between modbus TCP/IP and MQTT.

There are already a few things that do this, but didn't quite have the features I wanted.

The mapping of modbus registers to MQTT topics is in a simple YAML file.

YAML definition

Look at the Sungrow SH5k-20 configuration YAML for a working example.

Modbus device settings

ip: 192.168.1.89
port: 502
update_rate: 1

This is the address of the Modbus device to be polled. Presently only Modbus TCP/IP is supported. The update rate is in seconds. This defines how frequently the registers are polled for changes.

registers:
  - pub_topic: "forced_charge/mode"
    set_topic: "forced_charge/mode/set"
    retain: true
    pub_only_on_change: false
    table: 'holding'
    address: 13140
    value_map:
      enabled: 170
      disabled: 85
  - pub_topic: "forced_charge/period_1/start_hours"
    set_topic: "forced_charge/period_1/start_hours/set"
    pub_only_on_change: true
    table: 'holding'
    address: 13142

This section of the YAML lists all the modbus registers that you consider interesting.

pub_topic (Optional) This is the topic to which the value of this register will be published.

set_topic (Optional) Values published to this topic will be written to the Modbus device.

retain (Optional) Controls whether the value of this register will be published with the retain bit set.

pub_only_on_change (Optional) Controls whether this register will only be published if its value changed from the previous poll.

table (Required) The Modbus table to read from the device. Must be 'holding' or 'input'.

address (Required) The address to read from the device.

value_map (Optional) A list of human-readable and raw values for the setting. This will be used to translate between human-readable values via MQTT to raw values via Modbus.