Browse Prior Art Database

Incoming Scan Bus Inhibit

IP.com Disclosure Number: IPCOM000094382D
Original Publication Date: 1966-Oct-01
Included in the Prior Art Database: 2005-Mar-06
Document File: 2 page(s) / 54K

Publishing Venue

IBM

Related People

Lander, DH: AUTHOR [+2]

Abstract

Malfunctions causing permanent service requests among a plurality ºof input lines can be identified and isolated by circuitry. The latter sequentially examines each potential path and logically eliminates groups of lines containing the malfunctioning input.

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Incoming Scan Bus Inhibit

Malfunctions causing permanent service requests among a plurality ºof input lines can be identified and isolated by circuitry. The latter sequentially examines each potential path and logically eliminates groups of lines containing the malfunctioning input.

Using a telephone environment of two hundred twenty-five trunk circuits arranged in fifteen groups of fifteen trunks for an exemplary description, signal service requests are introduced for each trunk at terminals 10... 13 to partially condition And's 15... 18. By devices not shown, one redundant control unit A or B is selected by closure of normally open contacts such as 21 for sequentially scanning 15... 18 to detect service requests. A request at 10 is passed through Or 22 to be ultimately sensed by selected unit A or B. If a malfunction causes a permanent service request signal, it would appear to the system that all terminals of a group such as 10... 12 were requesting service thus radically degrading the system operation.

Assume unit A is on line and senses a permanent request malfunction since a signal remains on 36 when all select lines into 15...18 are deactivated. Unit A indicates to control logic 26 on 28 that an incoming scan check routine is to be initiated. Logic 26 then energizes 29 to cause all error latches L1... L15 to be set. Such action in turn causes all cutout relays to be actuated opening normally closed contacts 30... 32. If the request is still sensed at 36, the failure is in unit
A. Unit B is switched to replace unit A by appropriate con...