Open Source Access Control Messaging Standard

Draft Messaging Standard for Open Source Access Control

Low-level Signaling

Message format should be adaptable to the following mediums

• Serial
  • RS-485
    • Up to 32 devices per chain
    • 9600-57600BPS
    • Half-Duplex
  • RS-232

• Ethernet
• REST style API(http POST/GET API)
• SMS/Cellular
  • <140 characters or less per message

Desired Features

• Polling, and unique identification of nodes in the system
• Collision-handling and/or retry protocol
• CRC protocol for message integrity
• Encrypted/authenticated and cleartext messagig support
• Ability to interoperate if other protocols are on the same bus
  • Can ignore messages in wrong format
  • Graceful recovery/retry of messages
  • Ethernet-style back-off in case of collisions?
• Need s rich library of polling, sending and control messages

Existing Protocols

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• Royce Pipkins Access Control Project

//Copyright Royce Pipkins 2010 //May be used under the terms of the GPL V3 or higher. http://www.gnu.org/licenses/gpl.html /*

• ASCIIProtocol.h
• Created on: Mar 28, 2010
• Author: Royce Pipkins
• ASCII protocol driver
• Address and Type will be encoded as ascii-hex in the
• first four bytes after STX. The body string will follow
• as-is and will include the zero terminator. The next
• four bytes will be the 16 bit check sum of the everything
• past the STX up to the checksum expressed as ascii-hex
• [STX][ADDRESS][TYPE][BODYSTR][\0][CHECKSUM][ETX]
• The body string mustn't contain an STX or ETX or the receiver
• will reject the packet.
• /

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