DPM01 DECdataway Terminal Multiplexer

This document serves as a comprehensive guide for the installation, operation, and maintenance of the DPM01 DECdataway Terminal Multiplexer. The DPM01 is a microprocessor-based peripheral interface designed for Distributed Plant Management (DPM) Systems, providing four serial I/O ports (20 mA current loop or EIA RS232-C) to connect interactive terminals to a DECdataway. It acts as both a remote electrical interface and a data preprocessor, offloading character interrupt servicing and terminal functions from the host processor.

Key aspects covered include:

• General Description: The DPM01 is housed in a rugged, wall-mountable industrial cabinet, containing a microcontroller, two interface modules, and a power supply. It is configured via jumpers in its DECdataway connector or through down-line loading from the host, eliminating the need for internal switches.
• Specifications: Detailed electrical (e.g., 115/230 Vac, 50-60 Hz, 45W), environmental (operating temperatures, humidity), physical dimensions, and terminal interface characteristics (50-9600 Baud, asynchronous data format) are provided.
• Operating Modes: The unit features three modes controlled by a key switch: Normal (for online operation), Diagnostic (for self-tests on power-up or via MAINT switch), and Supervisory (for advanced testing, including port 0 online for host diagnostics or off-line terminal/cabling echo tests). Front panel LEDs indicate power status and port activity or diagnostic progress.
• Installation: Step-by-step instructions for unpacking, selecting a wall-mounting location, attaching the unit to a wall, and preparing/connecting DECdataway and terminal cables. It includes maximum cable length recommendations based on baud rate and details on pin assignments for various interface types.
• Field Acceptance & Troubleshooting: Procedures for initial power-up diagnostics, using loopback plugs to test each port, and connecting to the DPM host for system-level diagnostic tasks. Flowcharts are provided to guide operators through troubleshooting non-apparent failures, performing echo tests on terminals and cabling, and verifying DECdataway addresses.
• Appendices: Include an optional FDM Service Addendum outlining customer and Digital Equipment Corporation maintenance responsibilities, and DECdataway connector addressing data to aid in system configuration.