Allen Bradley 1756-DNB/D DeviceNet Communication Module

The Allen Bradley 1756-DNB/D, also cataloged as the 1756-DNB/D DeviceNet Communication Module, operates as a dedicated hardware component for DeviceNet cyclic data exchange and network object management within ControlLogix backplane-based communication architecture.

Configured for DeviceNet protocol execution in ControlLogix chassis systems, the Allen Bradley 1756-DNB/D (1756-DNB/D DeviceNet Communication Module) provides direct physical and logical mapping between Logix5000 controller tags and DeviceNet network devices via deterministic messaging and polling cycles.

Suffix Breakdown & Model Matrix

The “/D” suffix identifies a revision level within the 1756-DNB hardware lineage. No additional functional segmentation or field-configurable variants are defined in the provided specification.

Hardware Specifications

Backplane Bus Communication Velocity and DeviceNet Deterministic Network Scheduling (ControlLogix Integration Layer)

The 1756-DNB/D module executes cyclic DeviceNet polling synchronized with ControlLogix backplane scan execution. Network scheduling is governed by fixed baud rate selection and object-based I/O mapping between controller tags and DeviceNet nodes.

DeviceNet transaction timing is constrained by network node count and bus arbitration cycles. Each configured device participates in producer/consumer messaging or explicit messaging depending on connection configuration.

Backplane throughput consumption is proportional to active I/O assemblies and connection instance count, with deterministic update behavior enforced through ControlLogix task scheduling.

Frequently Asked Questions (FAQ)

Q: Does the 1756-DNB/D support hot-swapping in an active ControlLogix chassis?
A: Yes. The module supports chassis-level hot insertion. DeviceNet connections may require re-establishment after reinsertion.

Q: What limits DeviceNet network performance on this module?
A: Performance is limited by baud rate (125 / 250 / 500 kbps), node count (max 64), and bus arbitration timing.

Q: Can multiple DeviceNet devices be controlled simultaneously?
A: Yes. The module supports multiple simultaneous connections through cyclic I/O and explicit messaging mechanisms.

Field Installation Guidelines

Insert the module into a properly aligned 1756 ControlLogix chassis slot. Ensure full backplane connector engagement before energizing the system.

Use shielded twisted-pair DeviceNet cable with correct 5-pin connector termination. Maintain shield continuity along the full trunk line with single-point grounding.

Verify baud rate configuration across all network nodes before system startup. Mismatched baud settings will prevent node registration on the DeviceNet bus.

Route DeviceNet wiring away from high-current switching conductors to minimize electromagnetic coupling into low-voltage differential signaling lines.