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Browse Prior Art Database

Transmit to Receive Turnaround Detection

IP.com Disclosure Number: IPCOM000084520D
Original Publication Date: 1975-Nov-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Brodd, WD: AUTHOR [+2]

Abstract

Described is a transmit to receive turnaround detection scheme suitable for use in a serial-loop transmission system, in which the latent delay of the transmission network is equal to or exceeds the minimum message length which may be transmitted to the devices connected within the system.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 78% of the total text.

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Transmit to Receive Turnaround Detection

Described is a transmit to receive turnaround detection scheme suitable for use in a serial-loop transmission system, in which the latent delay of the transmission network is equal to or exceeds the minimum message length which may be transmitted to the devices connected within the system.

A central controller is usually provided for managing the flow of messages within the system. The controller will generally transmit messages for subsidiary stations on the network. When all of the outstanding messages have been transmitted or upon some arbitrary cycle, the controller will attempt to receive messages from the terminals or remote devices on the loop by turning the loop around. This may be accomplished in many ways. Preferably, however, the controller will issue some type of authorization signal which is accepted by the devices connected on the loop.

If no special provisions are made, the controller may receive and accept a message which it originated and directed to one of the attached terminals, and interpret that message as one originating from that terminal.

This problem may be overcome by transmitting from the controller a unique bit sequence hereinafter referred to as a turnaround sequence, immediately prior to transmitting a go-ahead sequence to the connected terminal. After switching to the receive mode, the controller ignores all messages or partial messages until it has detected the turnaround sequence previously...