NOTE: This project is no longer maintained. 

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The MIT License

Copyright (c) 2011 University of Nebraska, Omaha

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

This product will be used for good, not evil.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.

usbstack -  This module is based on the Honken USB Stack, which is released
            under the Creative Commons Share-Alike License.

dhcpc, uip  -   These modules are from uIP, and are released under the
                BSD license.

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INTRODUCTION

OpenPLC is designed to offer a cheap, open source alternative platform for
control when security and safety are not an issue.  The device uses similar
ladder logic and ModBus protocols as major PLC.  It also can produce and read
24V Hardware IO. Using these tools, this device is capable of performing
comparable work to that of a more expensive PLC.

The code is laid out as follows:
include - Global includes.
lib     - Global Libraries.
logic   - The Logic module: runs ladder logic and maintains virtual registers.
core    - The core PLC functions. main is here.
dhcpc   - The DHCP layer.
uip     - The open-source TCP-IP stack module
usb     - The usb module.
usbstack- The Honken USB stack
arch    - Architecture-specific functions (i.e. IO, Timers, etc.)

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INSTALLATION

There is currently a setup-deb.sh file in this folder.  Look it over, In the
event you are connected to the canonical repository, this should probably set
you up.

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MODULE OVERVIEW
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ARCH

The arch module contains the hardware-specific controls needed to interface
with the board.  It has subfolders containing the different supported
architectures for the system.

USBSTACK

The Usbstack module is based on the Honken USB Stack. Look at
DangerousPrototypes for more information. This has had to be severely
modified in order to make it compile for our system.