StorageWorks 16-Bit SCSI Bus Hub (DWZZH) User's Guide

This document is the User's Guide for the Digital Equipment Corporation's 16-Bit SCSI Bus Hub (DWZZH), published in October 1997.

Purpose and Function: The DWZZH-series SCSI bus Hubs are designed to expand and manage SCSI bus configurations. They act as converters and extenders, allowing the connection of up to three ports on a single logical SCSI bus. Their main functions include:

• Connecting differential physical SCSI buses to single-ended physical SCSI buses.
• Extending the maximum length of a SCSI bus (e.g., up to 20 meters for Single-Ended Ultra SCSI, 25 meters for Differential SCSI per segment).
• Providing radial disconnect, meaning if one connection fails, the remaining connections can continue to operate.

Key Features and Specifications:

• Compliance: SCSI-2 and draft SCSI-3 compliant, supporting data transfer rates up to 40 MB/s (UltraSCSI).
• SCSI ID: The Hub does not use a SCSI ID.
• Termination: It includes internal, factory-set active terminators for 16-bit operation on each port. TERMPOWER must be supplied from remote connections.

• Models:

  • DWZZH-21: Features two Single Ended SCSI bus connections and one Differential SCSI connection.
  • DWZZH-03: Features three Differential SCSI bus connections.

• Installation: Designed for installation in StorageWorks BA350 and BA356 shelves, where it draws power and mechanical support. It is used in end-bus SCSI bus configurations.

• Connectors/Cables: Uses 68-pin VHDCI SCSI connectors and requires BN37A-series shielded SCSI cables.
• Safety/Warnings: Warns against connecting differential cables to single-ended connectors (or vice-versa) as this will cause the SCSI bus to fail.
• Service: The product has no user-serviceable functions; all service must be performed by Digital Equipment Corporation personnel.

The guide also provides information on related documents, revision history, and a glossary of terms.