Allen Bradley 1756-DHRIO/E ControlLogix Communication Module

The Allen Bradley 1756-DHRIO/E, also cataloged as the 1756-DHRIO/E communication module, serves as a dedicated hardware component for DH+ message routing and Remote I/O scan execution within ControlLogix backplane-based ControlLogix chassis systems.

Configured for dual-protocol legacy network integration in ControlLogix platforms, the Allen Bradley 1756-DHRIO/E (1756-DHRIO/E communication module) provides direct physical and logical execution of DH+ and RIO data exchange across ControlLogix controllers and legacy PLC networks.

Suffix Breakdown & Model Matrix

No functional suffix segmentation beyond the base ordering code 1756-DHRIO/E. The “/E” designation does not introduce configurable hardware variants within the provided specification set.

Hardware Specifications

Backplane Bus Communication Velocity and Deterministic Legacy Network Bridging (ControlLogix DH+ / RIO Layer)

The 1756-DHRIO/E executes protocol bridging between ControlLogix backplane scan cycles and legacy serial network timing domains. DH+ and RIO channels operate as independent deterministic communication engines mapped to fixed baud configurations.

Backplane transactions are scheduled through ControlLogix chassis arbitration, while DH+ frame transmission follows token-based bus access rules. RIO scan execution maintains cyclic polling aligned with fixed rack and block transfer tables.

Signal timing resolution is constrained by baud rate selection and network node density, directly affecting update cycle latency across multi-drop configurations.

Frequently Asked Questions (FAQ)

Q: Does the 1756-DHRIO/E support hot-swapping in a live ControlLogix chassis?
A: Yes. The module supports chassis-level hot-swap. DH+ and RIO sessions may reset during reinsertion and require network reinitialization.

Q: What limits DH+ and RIO communication performance?
A: Performance is limited by configured baud rate, node count, and token rotation timing on DH+ plus cyclic scan intervals on RIO.

Q: Can DH+ and RIO channels operate simultaneously?
A: Yes. The module implements dual independent communication channels, allowing concurrent DH+ and RIO operation.

Field Installation Guidelines

Insert the module into a ControlLogix 1756 chassis slot with backplane alignment verified. Ensure full connector engagement before powering the chassis.

Use shielded twisted-pair cabling for DH+ and RIO networks. Maintain continuous shield integrity and implement single-point grounding to reduce common-mode noise coupling.

Configure baud rate switches prior to energization. Mismatch between node configuration and module settings will prevent network synchronization.

Avoid routing DH+/RIO cabling parallel to high-current switching conductors to limit induced interference on legacy serial lines.