Browse Prior Art Database

Test Terminator to Enable Test of SCSI Cables

IP.com Disclosure Number: IPCOM000103880D
Original Publication Date: 1993-Feb-01
Included in the Prior Art Database: 2005-Mar-18
Document File: 4 page(s) / 57K

Publishing Venue

IBM

Related People

Kochan, J: AUTHOR [+2]

Abstract

An SCSI test terminator design that enables testing of differential SCSI cables in a system environment is disclosed.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

Test Terminator to Enable Test of SCSI Cables

      An SCSI test terminator design that enables testing of
differential SCSI cables in a system environment is disclosed.

      The test terminator consists of a resistive network which
forces all of the SCSI lines on a differential SCSI bus active.  If
there is an open, or high resistance in a SCSI line, then the SCSI
line will not be forced active.  If the SCSI bus is read while the
test terminator is connected, any open or high resistance SCSI lines
can be detected.

      The SCSI bus is terminated on both ends by a terminator that
forces all of the SCSI bus lines inactive (see Fig. 1).

      For the test setup, the normal terminator is replaced by a test
terminator that forces all of the SCSI bus lines active.  The test
terminator can be moved to allow isolation to the actual failing item
(see Fig. 2).

High Resistance Detection Capability.

      The ability of the SCSI test terminator to detect high
resistance cable problems can be varied greatly by changing the
resistor values Rt and Rc.  Shown below are the test results for some
of the possible values of Rt and Rc.

+-----------------------------------------------------------------+
| Table 1.  Test Results for SCSI test terminator                 |
+----------------------+------------------------------------------+
|  Rt-Rc-Rt (Ohms)     | * Detectable total cable resistance      |
+----------------------+------------------------------------------+
|  191-150-191         | 25 to 70 ohms                            |
+--...