The Allen-Bradley 1756-DNB is a high-performance communication module designed for the ControlLogix platform, serving as a dedicated DeviceNet scanner. It enables seamless integration between ControlLogix processors and a wide array of DeviceNet-compatible field devices, including motor starters, drives, sensors, actuators, and distributed I/O systems.

Features

• Functions as a DeviceNet scanner for ControlLogix chassis environments.
• Supports communication with up to 64 DeviceNet nodes (addresses 00-63).
• Configurable communication rates: 125 Kbps, 250 Kbps, and 500 Kbps with automatic baud rate detection.
• Integrated network diagnostics and status monitoring via front-panel indicators.
• Backplane-powered operation with support for remote rack mounting via bridging modules.
• Supports Automatic Device Replacement (ADR) for simplified maintenance.

Applications

• Automotive Production: Weld cells, assembly sensors, and conveyor control.
• Oil & Gas: Telemetry, valve manifold control, and field instrumentation.
• Metals & Mining: High-vibration machinery, sorters, and heavy-duty processing gear.
• Water & Wastewater: Pump control, flow metering, and remote processing instruments.
• Warehouse & Fulfillment: AGV routing, sortation systems, and conveyor networks.

Technical Specifications

Installation Guidelines

• ESD Protection: Always use a grounded wrist strap when handling the module to prevent electrostatic discharge damage.
• Hot-Swapping: ControlLogix modules support RIUP (Removal and Insertion Under Power). However, you must disconnect the DeviceNet plug before removing the module to prevent electrical transients from affecting the network.
• Termination: The DeviceNet trunk line requires two 121-ohm termination resistors at the extreme ends of the network.
• Grounding: The network shield must be grounded at a single point only, typically at the DeviceNet power supply, to prevent ground loops.
• Configuration: Use RSNetWorx for DeviceNet to map I/O parameters and configure device settings.

FAQ

What is the primary function of the 1756-DNB?

The 1756-DNB acts as a bridge and scanner, allowing a ControlLogix controller to exchange data with distributed field devices over a DeviceNet network.

Can this module be used in a remote chassis?

Yes, the module can operate in a remote rack without a local CPU, provided there is a communication bridge (such as an EtherNet/IP or ControlNet module) in the same chassis to route data to the master controller.

How do I set the baud rate?

The module features Autobaud functionality to detect the network speed, or it can be manually configured via the front-panel buttons or through the RSLogix 5000 / Studio 5000 software environment.