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Diagnostics for a Polled Connection

IP.com Disclosure Number: IPCOM000086636D
Original Publication Date: 1976-Oct-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 22K

Publishing Venue

IBM

Related People

Edstrom, GH: AUTHOR [+2]

Abstract

A polled or daisy-chain connection usually consists of tag or control lines that control the timing of the various controlling and controlled units, as well as data lines for transferring data signals between the various units. In one arrangement, a set of lines (data out) transfer data signals from the controlling unit to any one of the addressed controlled units, while a similar set of lines (data in) transfer data signals from any of the addressed controlled units to the controlling unit during power-up sequencing and diagnostic procedures. Each controlled unit is assigned a bit position on the data-in lines. Accordingly, signals on a given data-in line signify that a given control unit is active and responding to control signals from the controlling unit.

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Diagnostics for a Polled Connection

A polled or daisy-chain connection usually consists of tag or control lines that control the timing of the various controlling and controlled units, as well as data lines for transferring data signals between the various units. In one arrangement, a set of lines (data out) transfer data signals from the controlling unit to any one of the addressed controlled units, while a similar set of lines (data in) transfer data signals from any of the addressed controlled units to the controlling unit during power-up sequencing and diagnostic procedures. Each controlled unit is assigned a bit position on the data-in lines. Accordingly, signals on a given data- in line signify that a given control unit is active and responding to control signals from the controlling unit. Further, each such assigned line-bit position is used to transfer status signals from the respective controlled unit to the controlling unit. In this manner, difficulties in the various respective controlled units can be easily identified.

During an initialization period, the controlling unit supplies all binary 1's on the data-out lines during a given control state condition. The controlled units each detect all binary 1's and then supply an appropriate status signal on their assigned respective bus-in line. Alternatively, the received binary 1's can be transferred by all of the controlled units to their bus-in lines, such that a logical OR function is performed. Then, i...