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Fault Isolation on a Multidriver Bus

IP.com Disclosure Number: IPCOM000041386D
Original Publication Date: 1984-Jan-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Schettl, MD: AUTHOR

Abstract

Fault isolation in a typical multidriver bus configuration is a manual operation and, therefore, time consuming. It is also prone to replacing the wrong component(s) until the failure is isolated and, therefore, a costly operation. Three typical configurations are shown in Figs. 1, 2, and 3. Generally, the bus is bidirectional (BiDi), each node contains a driver and a receiver, and one node has control of the bus at any one instant in time. Fig. 1 is a typical I/O channel, and the channel control logic has control of the bus. Commands and data are transmitted over the bus to and from the I/O device controllers. In most systems, each node on the bus is a Field Replaceable Unit (FRU). Fig. 2 is a similar configuration except that all of the nodes are on one FRU. Fig. 3 is a combination of Figs.

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Fault Isolation on a Multidriver Bus

Fault isolation in a typical multidriver bus configuration is a manual operation and, therefore, time consuming. It is also prone to replacing the wrong component(s) until the failure is isolated and, therefore, a costly operation. Three typical configurations are shown in Figs. 1, 2, and 3. Generally, the bus is bidirectional (BiDi), each node contains a driver and a receiver, and one node has control of the bus at any one instant in time. Fig. 1 is a typical I/O channel, and the channel control logic has control of the bus. Commands and data are transmitted over the bus to and from the I/O device controllers. In most systems, each node on the bus is a Field Replaceable Unit (FRU). Fig. 2 is a similar configuration except that all of the nodes are on one FRU. Fig. 3 is a combination of Figs. 1 and 2 in that some FRUs have multiple nodes. Two classes of problems, solid failures and intermittent failures, in two environments, field repair and manufacturing repair, are evident. Solid failures can be isolated by the replace and try procedure. In the field environment, this consists of replacing one FRU at a time until the problem is isolated. In the factory environment, the FRU replacement technique is also used; however, where the FRUs have multiple drivers, the "replace and try again" procedure must also be done at the chip or module level. Intermittent problems are the real bane for both the factory and field environments, because after the "replace and try again" procedure, no feasible amount of testing will verify if the problem has been corrected. This has caused a tremendous amount of frustration for customers and field personnel. It also degrades the quality of the product because the factory cannot guarantee quality repairs. The solution to these problems is...