Product Overview
The Allen-Bradley 1756-DNB is a DeviceNet™ scanner (master) communications module designed for installation in any I/O slot of a Rockwell Automation ControlLogix® 1756 series chassis. Acting as the bridge between a Logix5000™ controller—such as a 1756-L61, L63, L71, or L8x—and a DeviceNet network segment, the Allen-Bradley 1756-DNB autonomously scans up to 63 slave nodes (MAC IDs 0–63), exchanging I/O data using polled, strobed, change-of-state (COS), or cyclic messaging modes. It enables the control processor to read/write data from intelligent devices such as variable frequency drives (VFDs), smart motor starters, pneumatic valve banks, vision systems, barcode readers, and distributed 1792/1794 FLEX I/O—all over a single shielded twisted-pair trunk cable carrying both signal and 24 V DC bus power.The Allen-Bradley 1756-DNB connects to the DeviceNet network via a 5-position screw-terminal (Phoenix-style) open-style port supporting 125 kbps, 250 kbps, or 500 kbps baud rates, with automatic baud detection configurable through RSNetWorx™ for DeviceNet software. The module draws its logic power from the ControlLogix backplane (nominally 400 mA @ 5.1 V DC) and does not require separate module power for the network side—DeviceNet trunk power is supplied independently by a dedicated 24 V DC DeviceNet power supply. All I/O mapping, node configuration, and EDS-based device parameter access are handled within the Rockwell development environment, allowing the Allen-Bradley 1756-DNB to appear as a transparent extension of the control system rather than a standalone gateway requiring custom protocol coding.Widely deployed since the inception of the ControlLogix platform, the Allen-Bradley 1756-DNB remains the standard means of integrating legacy and current DeviceNet devices into modern Logix-based automation architectures, offering proven reliability, straightforward commissioning, and full CIP (Common Industrial Protocol) compliance for both standard and DeviceNet Safety devices when used with an appropriate safety network configuration.
Technical Specifications
Product Model | 1756-DNBManufacturer | Rockwell Automation / Allen-BradleyProduct Type | ControlLogix DeviceNet Scanner (Master) Communications ModuleSeries | Allen-Bradley 1756 ControlLogixDeviceNet Port | 1 × 5-pin screw terminal (CAN_H, CAN_L, Drain/Shield, +24 V DC, 0 V DC); open-style connectorBaud Rates | 125 kbps / 250 kbps / 500 kbps (software-selectable per DeviceNet spec)Maximum Nodes per Scanner | Up to 63 slave nodes (MAC ID 0–63); multiple scanners can coexist in one chassis on separate segmentsBackplane Current Draw (5.1 V DC) | 400 mA typicalBackplane Current Draw (24 V DC) | 0 mA (no 24 V draw from backplane)Typical Power Dissipation | 3.5 WNetwork Cable Type | Shielded twisted pair, DeviceNet-thickness (thick or thin) per ODVA specificationModule Width | 1 slot (Standard 1756 single-width module)Operating Temperature | 0 °C to +60 °C (32 °F to 140 °F)Storage Temperature | -40 °C to +85 °CHumidity (non-condensing) | 5 % to 95 % RHEnclosure Rating | IP20 (when installed in enclosed panel)Agency Approvals | UL Listed, cULus, CE, C-Tick, ODVA conformanceConfiguration Software | RSNetWorx for DeviceNet, Studio 5000 / RSLogix 5000 (Add-On Profile / Generic Device support)Compatible Controllers | All Logix5000 controllers (1756-L55, L6x, L7x, L8x series)
