moat-modbus 0.6.2

Modular async modbus client and server

This is an anyio-enabled async frontend for pymodbus.

Usage

Check the example client and server for rudimentary usage.

Documentation patches gladly accepted.

Background

moat-modbus diverges from pymodbus in that it does not expose a “data store” context to the user. Instead, every bus value is a separate object, with arbitrary length and encapsulating its own encoding and decoding rules.

A Modbus server exposing writeable registers only needs to

• register the value in question

• wait for it to be written to

The rest happens behind the scenes.

Device Server

As some Modbus devices only allow ine server at a time, MoaT’s Modbus supports a simple bidirectional gateway.

How to get there:

• Write a generic device description. Put it in the modbus-data repository.

• Add an interface overlay that describes which topic to send the data to / which topic to read.

• Run moat modbus dev poll FILE.yaml. You can use a generic systemd service if you copy the file to /etc/moat/modbus.

The values can be modified (factor+offset); the gateway works in both directions (command/state).

TODO

• configurable codecs

• get/set attributes

• pack multiple values into a message

• read-after-write if no slot