The Allen-Bradley 1756-DNB is a specialized communication bridge and scanner module designed for the ControlLogix platform. It enables seamless integration between a ControlLogix controller and a DeviceNet network, facilitating real-time data exchange with distributed field devices such as drives, sensors, motor starters, and operator interfaces.
Features
Serves as a high-performance DeviceNet scanner for ControlLogix chassis environments.
Supports up to 64 DeviceNet nodes with configurable addressing from 00 to 63.
Provides selectable communication baud rates of 125 Kbps, 250 Kbps, and 500 Kbps.
Integrated diagnostic capabilities for network health and status monitoring.
Backplane-powered design for streamlined installation within standard ControlLogix racks.
Supports Automatic Device Replacement (ADR) for simplified maintenance.
Applications
Automotive Manufacturing: Managing weld cells, assembly sensors, and conveyor logic.
Oil and Gas: Interfacing with field instruments, valve manifolds, and remote telemetry units.
Metals and Mining: Connecting heavy machinery, sorters, and high-vibration equipment.
Water and Wastewater: Integrating flow meters, pumps, and process control instrumentation.
Warehouse Logistics: Enabling sortation systems and AGV routing control.
Technical Specifications
Model
1756-DNB
Series
ControlLogix
Manufacturer
Allen-Bradley
Max DeviceNet Nodes
64
Isolation Voltage
30V
Power Dissipation
5.8 Watts
Thermal Dissipation
19.8 BTU/hr
Weight
0.25 kg
Installation Guidelines
Ensure the ControlLogix chassis power supply has sufficient capacity to support the module's current draw (typically 350 mA at 5.1V DC).
Always disconnect the DeviceNet cable before attempting to hot-swap the module to prevent electrical transients from affecting the network.
The DeviceNet trunk line requires two 121-ohm termination resistors at the extreme ends of the network.
Maintain single-point grounding for the network shield, preferably at the DeviceNet power supply location.
Verify firmware compatibility, particularly when transitioning between older series modules and newer Series E hardware.
FAQ
What is the primary function of the 1756-DNB?
The 1756-DNB acts as a bridge and scanner, allowing a ControlLogix processor to read inputs from and write outputs to remote DeviceNet-compliant field devices.
Is this module compatible with remote chassis configurations?
Yes, the 1756-DNB can be installed in a remote rack without a local CPU, provided a bridge module (such as EtherNet/IP or ControlNet) is present to facilitate communication with a master controller in a separate chassis.
How is the baud rate configured?
The module supports Autobaud detection, or you can manually configure the network speed and node address via the front-panel interface or through RSNetWorx for DeviceNet software.
