Allen-Bradley 1771-DB PLC-5 BASIC Communication Module

Product Overview

The 1771-DB provides a powerful BASIC-language programming environment within the Allen-Bradley PLC-5 chassis. This module handles complex mathematical calculations, string manipulations, and custom serial protocols that standard ladder logic cannot efficiently execute. We supply this unit in 100% Brand New condition, providing a vital solution for plants maintaining legacy infrastructure that requires specialized ASCII or DH485 data processing.

Technical Specifications

Engineering Advantages

• Offload Complex Computation: The 1771-DB contains its own microprocessor to execute BASIC code. This design offloads floating-point math and reporting tasks from the main PLC-5 processor, preventing scan-time degradation in high-speed applications.

• Custom Protocol Flexibility: The PRT1 and PRT2 ports allow engineers to write custom drivers for third-party hardware, such as bar code scanners, weigh scales, or printers. This capability bridges the gap between the PLC backplane and non-Rockwell peripheral devices.

• Non-Volatile Memory Protection: The module stores user programs in battery-backed RAM or optional EPROM. This ensures the system retains critical logic and communication parameters during total power loss on the factory floor.

• Simplified Data Interfacing: Utilizing the DH485 port, the 1771-DB integrates easily into local operator interface networks. It acts as a data concentrator, gathering information from multiple sources and presenting a unified data block to the host controller.

FAQs

How do I program the 1771-DB module?

You connect a terminal or a PC running terminal emulation software to the PRT1 port. The module utilizes a specialized BASIC instruction set optimized for industrial I/O, allowing you to read and write directly to the PLC-5 data table.

Can I replace a faulty 1771-DB without changing the PLC program?

Yes. As long as you load the original BASIC source code into the new 1771-DB and match the jumper settings for the communication ports, the PLC-5 processor will recognize the module via the same backplane addresses.

What are the power considerations for a full 1771 rack?

The 1771-DB pulls a significant 0.75A from the 5VDC backplane. When installing this module, you must verify that your 1771-P4, P5, or P7 power supply has sufficient headroom to support this load alongside your existing I/O modules.

Does this brand-new unit include the original internal battery?

While the unit is brand new, we recommend installing a fresh 1771-BA battery upon commissioning to ensure maximum memory retention life, as the module relies on this battery to maintain the BASIC program during power-down cycles.