RModBus

RModBus - free implementation of ModBus protocol in pure Ruby.

Features

Ruby 2.5+ and JRuby (without serial ModBus RTU)
TCP, RTU, RTU over TCP protocols
Client(master) and server(slave)
16, 32-bit and floating point registers

Supported functions

Read Coils (0x01)
Read Discrete Inputs (0x02)
Read Holding Registers (0x03)
Read Input Registers (0x04)
Write Single Coil (0x05)
Write Single Register (0x06)
Write Multiple Coils (0x0F)
Write Multiple Registers (0x10)
Mask Write register (0x16)

Installation

Download and install RModBus with the following:

gem install rmodbus

Or if you are using bundler, add to your Gemfile:

gem 'rmodbus'

If you want to use ModBus over serial, you will also need to install the 'ccutrer-serialport' gem. If you are using bundler, add to your Gemfile:

gem 'ccutrer-serialport'

If you want to use ModBus::TCPServer or ModBus::RTUViaTCPServer, you will also need to install the 'gserver' gem. If you are using bundler, add to your Gemfile:

gem 'gserver'

Please note that GServer is deprecated, and I'm looking for a better solution. Contributions are welcome!

Example

  require 'rmodbus'

  ModBus::TCPClient.new('127.0.0.1', 8502) do |cl|
    cl.with_slave(1) do |slave|
      # Read a single holding register at address 16
      slave.holding_registers[16]

      # Write a single holding register at address 16
      slave.holding_registers[16] = 123

      # Read holding registers 16 through 20
      slave.holding_registers[16..20]

      # Write holding registers 16 through 20 with some values
      slave.holding_registers[16..20] = [1, 2, 3, 4, 5]
    end
  end

Versioning

This project will follow http://semver.org/

Given a version number MAJOR.MINOR.PATCH, increment the:

MAJOR version when you make incompatible API changes,
MINOR version when you add functionality in a backwards-compatible manner, and
PATCH version when you make backwards-compatible bug fixes.