1756-dhrio_e_communication_module

Each of the two independent channels on the 1756-DHRIO/E​ can be individually configured as either a DH+ link or a Remote I/O scanner, providing exceptional flexibility for mixed network environments. When set to DH+ mode, the module acts as a gateway, allowing ControlLogix controllers to read from and write to DH+ devices across the network. In Remote I/O mode, the 1756-DHRIO/E​ functions as a scanner, managing data exchange with remote chassis (such as those using 1771‑ASB adapters) and supporting both discrete I/O and block transfers. This dual‑role capability makes the module an indispensable tool for phased migration projects, brownfield modernizations, and extending the service life of reliable but aging field equipment.

Technical Specifications

Main Features and Advantages

Dual‑protocol flexibility: The most significant feature of the 1756-DHRIO/E​ is its ability to operate each of its two channels independently as either a DH+ station or a Remote I/O scanner. This eliminates the need for separate gateway hardware in hybrid environments. Engineers can configure one channel to handle messaging with a network of legacy PLC‑5 processors while using the other channel to scan a line of 1771 remote I/O racks, all within a single module footprint. The module supports the full suite of DH+ functionality, including peer‑to‑peer messaging and bridge routing between networks, ensuring compatibility with existing network topologies.High‑capacity RIO scanning: When configured for Remote I/O, the 1756-DHRIO/E​ provides robust scanner capabilities that support up to 32 logical rack connections per channel. It efficiently handles both discrete I/O data and block transfers, enabling communication with complex analog modules and intelligent devices on the RIO link. This high density allows a single module to manage extensive remote I/O systems, reducing the number of communication modules required in the chassis and optimizing slot usage in the ControlLogix rack.Seamless ControlLogix integration: The 1756-DHRIO/E​ leverages the full power of the ControlLogix backplane and the producer/consumer model. Data from DH+ nodes and Remote I/O devices are mapped directly into the controller’s tag database, making the legacy data accessible as standard tags within Logix‑based programs. This abstraction layer simplifies programming and troubleshooting, as engineers do not need to write low‑level protocol‑specific code. The module is fully configurable within the Studio 5000/RSLogix 5000 environment, with intuitive configuration screens for setting network addresses, baud rates, and rack mapping.

Application Field

The 1756-DHRIO/E​ is primarily deployed in industrial brownfield modernization projects where preserving investments in legacy automation equipment is a critical business objective. In the automotive manufacturing sector, it is commonly used to integrate existing PLC‑5‑controlled paint shops or welding lines into a new plant‑wide ControlLogix‑based MES or SCADA system. The module allows for a phased migration approach, where the control logic can be gradually moved to a new Logix controller while the existing field I/O and device networks remain operational, minimizing production downtime.Within the oil & gas and petrochemical industries, the 1756-DHRIO/E​ provides a reliable bridge for critical process units that rely on proven but aging DH+ networks for inter‑PLC communication. It enables modern ControlLogix safety controllers to gather process data from legacy PLC‑5 systems without compromising the integrity of the existing control strategy. Similarly, in power generation and water/wastewater treatment facilities, the module is instrumental in connecting Remote I/O networks (often based on 1771‑ASB adapters) located in distant substations or pump houses back to a central control room running on a contemporary Logix platform, extending the lifecycle of remote field wiring and termination panels.