From: Robert Klemme <shortcutter@...>
Date: 2011-02-21T23:54:22+09:00
Subject: Re: Using Ruby to connect with multiple IP Input output interface, Netiom.

On Mon, Feb 21, 2011 at 3:15 PM, Nick Jackson <nick.jackson25@gmail.com> wrote:
> I am trying to create an application written in ruby which communicates
> with multiple input/output interfaces over TCP/IP. The IO interface I am
> using is called a NETIOM. The interface has 16 digital inputs and 16
> digital outputs.

For us it is more important to know the protocol that this device
speaks (I mean the _network_ protocol which you are trying to
utilize).

> This code works for one Netiom device and is also able to detect inputs
> being pressed but the code exits after a little while. I have been
> experimenting with classes and arrays but not getting anywhere.
>
> require 'socket'
> server = TCPServer.open(3012)
> @socket = server.accept
> @socket.puts "SEND\r\n"

This should be @socket.write "SEND\r\n".

> while line = @socket.gets

If your line terminator is "\r\n" then you probably also want to use

TERM = "\r\n".freeze

while line = @socket.gets TERM

>  puts line.chop

I'd rather use

line.chomp! TERM

> end
>
> this code returns:
>
> Digital inputs 1-8 : 11111111
> Digital inputs 9-16: 11111111
> Digital outputs 1-8 : 00000000
> Digital outputs 9-16: 00000000
>
>
> It would be great if I can have some help with the following:
>   > handling multiple interfaces

Not sure what that means.  Do you want multiple clients to connect?

>   > being able to send a message to a single interface and then see its
> response

You may want to look at IO#expect ("ri19 IO#expect").

>   > 'doing something' when an input is triggered and being able to
> identify which input and interface it was triggered on.
>
> Take a look at this for more info.
> http://stackoverflow.com/questions/5066943

I'd start by creating a handler class per connection.  This could look
like this:

require 'socket'

class DeviceHandler
  TERM = "\r\n".freeze

  def initialize(socket)
    @socket = socket
    @thread = Thread.new do
       @socket.each_line TERM do |line|
         data = parse(line)
       end
    end
  end

  # more methods...

private
  def send(...)
    @socket.write(... + TERM)
  end
end

server = TCPServer.open(3012)
handlers = []

while (client = server.accept)
  handlers << DeviceHandler.new(client)
end

But how this is really set up (and especially if you need to start a
thread in the constructor) hugely depends on the protocol spoken by
the device and what you want to do with it.

Cheers

robert


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