Copyright (c) 2011-2012, Leif Bruder <leifbruder@googlemail.com>

Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.

THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.


Beckhoff PLC driver for Java 0.1
================================
This package provides a simple way to access Beckhoff PLCs via the AMS/ADS
protocol from pure Java. Variables on the PLC can be read and written,
and notifications can be used to have the PLC inform the Java program
of changes asynchronously. Symbol information is read from a TPY file
as provided by the Beckhoff system.

This code is by no means complete. It started as an experiment, when I
had to create a similar library for my employer, but could not implement
some of the ideas I had in mind. This stuff was written in my spare
time and has NO connection to the code I wrote at work -- this is a
Pure-Java project, whereas the code written for my employer was a Scheme
library. Having read "Clean Code" a while ago, I wanted to try some of
the principles detailed there, and this code base is my playground. Still
trying to get into the Test First mentality...

This code is based on the freely accessible Beckhoff Information System
only.  I go to great lengths to keep it free from any commercial claims,
especially by my employer. I don't have a Beckhoff PLC or a Windows PC
for that matter, so I can NOT test the code, as testing at work would make
it my employer's property. So I have to rely on unit tests at the moment.
Do not except this code to work 100% correctly.


Help wanted
================================
What I could use at this point:

- TPY files provided without copyright or IP claims
- Beta testers!
- Ideas for additional functionality :)

Please keep in mind that I want to keep this project under the ISC
license, so I can not accept anything with a questionable IP background.


TODO for version 0.2
================================
- Complete Toolbox tests, esp. double/float conversion (see TestToolbox.java)
- Unit tests in general
- Support ENUM data type in TPY files, map to integer
- Implement notification handling
=> First version that is actually useful


TODO for version 0.3
================================
- Add support for two-dimensional arrays
- Read/Write multiple variables with a single AMS roundtrip
- Notifications on variable blocks (= multiple variables observed
  with a single notification)


TODO for version 0.4
================================
- Retrieve TPY file from FTP server on the PLC
- TPY watchdog: TPY file matches project? If not, disconnect immediately
  to prevent damage due to writing to wrong addresses
- Connection watchdog to re-open connections if broken


TODO for version 0.5
================================
- Respect word aligning on BX... systems, endianness for REAL values etc.


TODO for version 1.0
================================
- Find someone and/or a PLC to test the system without IP attached
- Test, test, test.
- Fix bugs.