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Full Duplex Transport Layer Specification Page 1 of 5

ZonePRO Full Duplex Network and Data Link Layer Specification

Author:

John Lee

Creation Date:

January 7, 2004

Revision:

1.0

Last Edit Date:

April 27, 2004

Description:

Data Link and Network Layer specification for full duplex point-to-point

communication

1. Overview

This document outlines the Harman International data link and network layers for full duplex 232 or 485

point to point links .

2. Physical Layer (PHY)

This section defines the physical layer specification, including signaling, terminations, DC biasing, and

ground isolation.

2.1. Encoding

Data is transmitted NRZ encoded, LSB first as is shown below:

We refer to a logic 1 as a mark, a logic 0 as a space to conform with the RS-232 specification.

A stop bit is provided after each transmitted byte of data and is used for guarantee a falling edge on the

next start bit. A stop condition is mark for one bit interval and will be present after each framing bit.

Bits 7 through 0 represent the transmitted data.

The falling edge of the start bit is used to sync the UART to the beginning of the transmitted byte.

2.2. Baud Rate

The following baud rates can be supported by the DriveRack RS-232 and RS-485 full duplex data link

layers: 1200, 2400, 4800, 9600, 19200, 38400, 57600, and 115200.

2.3. Breaks and Line Faults

Breaks are considered a violation of the protocol and should force a resync if received.

2.4. Flags

Flags may be passed between the stations to mark layer events. A flag is a single byte sent between

frames. The following flags are defined:

Flags

Flag Value Function

ACK A5h Sent on positive receipt of a frame send via guaranteed

delivery.

NAK DAh Sent on negative receipt of a frame send via guaranteed

delivery.

Ping 8Ch Send by station if no activity is present. Used to detect loss of

link.

Resync Request FFh Send by a receiving station if it believes its out of sync with the

sending station.

Resync Acknowledgement F0h Send by a station after receiving a Resync Request flag.

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Full Duplex Transport Layer Specification Page 1 of 5 ZonePRO Full Duplex Network and Data Link Layer Specification Author: John Lee Creation Date

Pagina 2 - ± 3V into an

Full Duplex Transport Layer Specification Page 2 of 5 2.5. Ping To detect a loss of communication between host and DriveRack, each unit will issue

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Full Duplex Transport Layer Specification Page 3 of 5 will be performed optically for the RS-485 interface. Ground isolation for the RS-232 inter

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Full Duplex Transport Layer Specification Page 4 of 5 the received frame or if the receiving stations receive queue is full, the station should res

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Full Duplex Transport Layer Specification Page 5 of 5 CRC 8 bit calculation – 8 bit Bcc(new char) = Network_CCITT_8_Table[(UCHAR)(bcc ^ (new_char)

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