Browse Prior Art Database

In-House Data Bus

IP.com Disclosure Number: IPCOM000048206D
Original Publication Date: 1981-Dec-01
Included in the Prior Art Database: 2005-Feb-08
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Gergaud, C: AUTHOR

Abstract

In a system in which a high speed data bus is used to connect several low cost terminals to a cluster controller, means are provided here for enabling full duplex operations of the multi-drop connected terminals.

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In-House Data Bus

In a system in which a high speed data bus is used to connect several low cost terminals to a cluster controller, means are provided here for enabling full duplex operations of the multi-drop connected terminals.

As shown in the figure, the terminals are connected to a multi-drop full duplex line (one input line, one output line) attached to the cluster controller. Each terminal is connected to a number of input devices (e.g., contact sense devices) providing status information forwarding to the cluster controller. Each terminal is also connected to a number of output device (i.e., contact drive devices) to be controlled by the cluster controller.

Each of these non-intelligent terminals has been provided with an input message register and an output message register, respectively, intended for storing contact sense statuses and contact drive controls. The cluster controller sends output messages having the following format: Flag (F): 8-bit SDLC (Synchronous Data Link Control) stuffing

technique

Terminal address (A) or device address within the terminal

Data: 1 bit per output device line to be controlled

Check (C) byte

Flag (F)

When a terminal is selected by being addressed, it registers output message data bits and uses these bits to control the corresponding output device (e.g., contact drive). In addition, the selected terminal uses the received address information to control the terminal input message register and send back to the cluster cont...