DEC 3000 Systems: Special Information for PTT Network Users

This document, published in January 1995, provides updated installation and technical information for PTT (Public Telecommunications Terminal) network users of DEC 3000 AXP systems in specific European countries and the United Kingdom. Serving as an addendum to existing system manuals, it details critical specifications for various DEC 3000 models and their associated system and I/O modules.

Key areas covered include:

• Service Categories: It outlines service specifications for system and I/O modules, detailing interface types (X.21bis, V.24/V.28), supported data rates (up to 9600 bps for most operators, 19200 bps not supported), and approved extension cables with a total length limit of 27 feet.
• Host Power Rating: Emphasizes that the total power drawn by the system, I/O modules, host, and auxiliary equipment must not exceed the host power supply's rating, providing specific voltage and maximum current details for different configurations.
• Module Isolation: Defines necessary clearance and creepage distances to ensure safety and system approval, advising consultation with a telecommunications safety engineer if unsure about installation.
• Safety Status: Categorizes all interconnection points as Telecommunications Network Voltage (TNV) and/or Safety Extra Low Voltage (SELV) circuits, specifying that communication ports are TNV operating within SELV limits, ISDN ports are TNV, and all other ports are SELV.
• Cable Approval and Supported Cables: States that modules are approved for direct digital circuit connection using cables conforming to British standard BS6623. It provides a pin layout for the system module connector and lists specific approved V.24 extension cables.
• Intervening Equipment: Stipulates that any additional equipment or wiring connected between the module and a digital circuit must not compromise electrical conditions and must comply with relevant approvals or installation codes of practice.

The document ensures that DEC 3000 systems meet PTT network requirements when properly installed.