Browse Prior Art Database

Improved Diagnostic Loop Operation

IP.com Disclosure Number: IPCOM000038082D
Original Publication Date: 1989-Nov-01
Included in the Prior Art Database: 2005-Jan-31
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Irwin, JW: AUTHOR

Abstract

A method is described wherein a new diagnostic feedback path (3) is provided between serial I/O channels located on the same chip or card in addition to the usual paths (1, 2) within the individual I/O channels. When any of the diagnostic paths in a channel is enabled, the analog output of that channel is disabled.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 75% of the total text.

Page 1 of 1

Improved Diagnostic Loop Operation

A method is described wherein a new diagnostic feedback path (3) is provided between serial I/O channels located on the same chip or card in addition to the usual paths (1, 2) within the individual I/O channels. When any of the diagnostic paths in a channel is enabled, the analog output of that channel is disabled.

The conventional feedback paths (1, 2) permit partial diagnosis of a channel by looping back channel output at the last parallel data stage (1) and at the last serial digital data stage (2). The diagnosis provided by such conventional paths is limited in scope by the large amount of internal channel logic that is shared between the transmit and receive portions of the channel. For instance, inbound DMA cannot be tested by either path 1 or 2 because the channel DMA logic is operating in the outbound DMA mode to obtain the test data for transmission.

The addition of read-only parallel paths (3) between channel pairs allows for full duplex testing by enabling the receive paths of pairs of sibling channels. Both channels may be fully diagnosed including automatic responses without externally transmitting data. As an additional benefit, the response timings of the channels can be determined independent of link transmission delays.

By enabling receive path 3 on only one of a pair of channels, a unique monitor mode is created where the enabled channel can monitor the transmissions of the sibling channel during a conversation...