Ruby Modbus
Constructs modbus standard datagrams that make it easy to communicate with devices on modbus networks. It does not implement the transport layer so you can use it with native ruby, eventmachine, celluloid or the like.
You'll need a gateway that supports TCP/IP.
Install the gem
Install it with RubyGems
gem install modbus
or add this to your Gemfile if you use Bundler:
gem 'modbus'
Usage
require 'modbus'
modbus = Modbus.new
# Reading input obtained from the network
# The class instance performs buffering and yields complete ADUs
modbus.read(byte_string) do |adu|
adu.header.transaction_identifier # => 32
# Response PDU returned
if adu.exception?
# Get error message
puts adu.value
# Error code
puts adu.pdu.exception_code
else
case adu.function_name
when :read_coils
# raw response data
puts adu.pdu.get.data.bytes
# or values
puts adu.value # => [true, false, true, false, false, false, false, false]
when :read_input_registers
# Grab the 16 bit values
puts adu.value # => [1234, 8822]
end
end
end
# You can generate requests like so (writing multipe coils starting from 123)
request = modbus.write_coils(123, true, true, false)
byte_string = request.to_binary_s
# Read 4 coils starting from address 123
request = modbus.read_coils(123, 4)
byte_string = request.to_binary_s
# Send byte_string to the modbus gateway to execute the requestLicense and copyright
MIT