Allen-Bradley 1794 FLEX I/O Modules – 1794-ADNX

Technical Dossier

Product Details And Specifications

Allen-Bradley 1794 FLEX I/O Series Technical Notes

The Evolution of 1794 FLEX I/O Architecture

The 1794 FLEX I/O series was introduced in the mid-1990s as Rockwell Automation's response to the growing demand for distributed I/O architectures that could reduce field wiring costs without sacrificing scan-time performance. The initial release supported DeviceNet (1794-ADN) as the primary network interface, targeting machine-level automation where DeviceNet's peer-to-peer messaging model was already established. As plant-wide Ethernet adoption accelerated in the early 2000s, Rockwell introduced the 1794-AENT EtherNet/IP adapter, enabling the FLEX I/O platform to participate in the Integrated Architecture framework alongside ControlLogix and CompactLogix controllers. The 1794-ACN15 ControlNet adapter followed, addressing process industries where ControlNet's scheduled, deterministic communication was mandated by safety and regulatory standards. Across generations, the backplane communication protocol remained consistent, allowing legacy I/O modules (analog, digital, specialty) to be reused with newer network adapters — a critical compatibility feature for facilities managing 20+ year asset lifecycles. As of 2024, the 1794 FLEX I/O series is classified by Rockwell Automation as a mature product line. While active manufacturing continues for most catalog numbers, the platform is no longer receiving new feature development. End users are advised to evaluate migration paths to the 5000 FLEX I/O (Catalog 5094) for new installations, while existing 1794 deployments remain fully supportable through Rockwell's long-term availability program and third-party spare parts suppliers such as DriveKNMS.

1794 FLEX I/O Full Catalog & Functionalities (SKU List)

Communication Adapters

• 1794-ADNX: DeviceNet adapter with extended diagnostics; supports up to 8 I/O modules per bank, 500 kbps max data rate.
• 1794-ADN: Standard DeviceNet adapter; predecessor to ADNX, compatible with all 1794 I/O modules.
• 1794-AENT: EtherNet/IP adapter; 10/100 Mbps, supports CIP messaging and DLR (Device Level Ring) topology.
• 1794-ACN15: ControlNet adapter; supports scheduled and unscheduled messaging at 5 Mbps.
• 1794-APB: PROFIBUS-DP adapter; supports DP-V0 and DP-V1 communication classes.

Digital Input Modules

• 1794-IB16: 16-channel 24 VDC sourcing digital input module; 3 ms input filter, IEC 61131-2 Type 1 compliant.
• 1794-IB32: 32-channel 24 VDC digital input module; high-density format for space-constrained panels.
• 1794-IA16: 16-channel 120 VAC digital input module; for legacy AC field device integration.

Digital Output Modules

• 1794-OB16: 16-channel 24 VDC sourcing digital output module; 0.5 A per channel, short-circuit protected.
• 1794-OB32: 32-channel 24 VDC digital output module; 0.25 A per channel, high-density configuration.
• 1794-OW8: 8-channel relay output module; Form A contacts, 2 A per channel, suitable for motor starter control.

Analog Input Modules

• 1794-IE8: 8-channel analog input module; 4–20 mA / 0–10 VDC selectable per channel, 12-bit resolution.
• 1794-IF4I: 4-channel isolated analog input module; 16-bit resolution, ±10 VDC or 4–20 mA, channel-to-channel isolation.
• 1794-IR8: 8-channel RTD input module; supports Pt100, Pt1000, Ni120, and Cu10 sensor types.
• 1794-IT8: 8-channel thermocouple input module; supports J, K, T, E, R, S, B type thermocouples, cold-junction compensated.

Analog Output Modules

• 1794-OE4: 4-channel analog output module; 4–20 mA / 0–10 VDC selectable, 12-bit resolution.
• 1794-OF4I: 4-channel isolated analog output module; 16-bit resolution, channel-to-channel isolation for precision process control.
• 1794-OE12: 12-channel analog output module; high-channel-count format for valve positioner and actuator applications.

Terminal Bases & Power

• 1794-TB3: 3-wire terminal base; standard wiring interface for most 1794 I/O modules.
• 1794-TB3S: 3-wire terminal base with spring-clamp terminals; vibration-resistant wiring for mobile or high-vibration environments.