Product Overview

The Allen-Bradley 1785-L30B is an enhanced PLC-5/30 series processor designed to serve as the central intelligence for medium-to-large scale industrial automation systems. This module provides a robust platform for executing complex logic, timing, and counting instructions, as well as sophisticated analog signal processing. With a 32K word user memory capacity, the 1785-L30B is optimized for applications requiring distributed control across expansive factory floors, bridging the gap between localized machine logic and plant-wide communication networks.

This controller is characterized by its high-density I/O management and flexible networking options. It is capable of addressing up to 1,024 total I/O points (any mix of digital and analog) and supports up to 28 Remote I/O racks. Its multi-protocol communication ports allow it to function as a primary node in Data Highway Plus (DH+) networks, facilitating seamless data exchange with other controllers, HMIs, and SCADA systems.

Communication and Network Versatility

The 1785-L30B is engineered with a versatile port configuration that supports both legacy and modern industrial communication requirements.

• Dual-Function Ports: Features two combination ports that can be independently configured for DH+ messaging or Universal Remote I/O (RIO) scanning.

• Serial Interface: Includes a dedicated 25-pin RS-232C/422A/423 port for local programming, modem connections, or interfacing with ASCII devices like barcode scanners and printers.

• Distributed Expansion: Utilizing the RIO protocol, the controller can manage I/O chassis located thousands of feet from the main processor, reducing wiring costs and increasing system modularity.

• Network Integration: Through the addition of side-car modules, the 1785-L30B can be integrated into Ethernet/IP environments for high-speed supervisory control and data acquisition.

Technical Specifications

• Manufacturer: Allen-Bradley (Rockwell Automation)

• Model Number: 1785-L30B

• Series: PLC-5/30 Enhanced

• User Memory: 32K Words

• Total I/O Capacity: 1,024 Max (Analog or Digital)

• Remote I/O Racks: 28 Racks Max

• Backplane Current Draw: 3.3A @ 5V DC

• Power Dissipation: 16.5 Watts

• Battery Backup: Lithium battery for CMOS RAM (retention up to 84 days without power)

• Operating Temperature: 0°C to 60°C (32°F to 140°F)

• Weight: 1.18 kg (2.6 lbs)

• Dimensions: 4.8 x 15 x 27.3 cm

Operational Security and Diagnostics

• Physical Mode Control: A front-panel three-position keyswitch provides hardware-level security, allowing users to toggle between RUN (execution only), PROGRAM (logic editing), and REMOTE (software-based mode switching) modes.

• Status Monitoring: The module is equipped with clear LED indicators (PROC, BATT, FORCE, COMM) that provide instant diagnostic feedback on controller health, battery voltage levels, and communication activity.

• Memory Integrity: The integrated lithium battery ensures that the user program and data table values are preserved during power outages, preventing the need for field-side reprogramming after a shutdown.

• Forced I/O Protection: The "FORCE" LED alerts operators when I/O points have been manually overridden in software, an essential safety feature for maintenance and commissioning.