Allen-Bradley 1797 FLEX Ex Modules – 1797-IE8NF

Technical Dossier

Product Details And Specifications

Allen-Bradley 1797 FLEX Ex Series Technical Notes

The Allen-Bradley 1797 FLEX Ex series is a purpose-engineered intrinsically safe I/O platform designed for deployment in hazardous area installations — specifically ATEX Zone 1/2 and NEC Class I Division 1/2 environments. It is widely installed across global heavy industry sectors including petrochemical refineries, offshore oil & gas platforms, chemical processing plants, and nuclear facility instrumentation loops. The 1797 series interfaces directly with the 1794 FLEX I/O backplane architecture and communicates via standard ControlNet, DeviceNet, or PROFIBUS adapter modules, making it a critical bridge between field instrumentation and Rockwell Automation control systems. Its compact DIN-rail mounting profile and intrinsic safety certification have made it a long-term standard in facilities where explosive atmosphere compliance is non-negotiable.

The Evolution of 1797 FLEX Ex Architecture

The 1797 FLEX Ex platform was introduced as an extension of Rockwell Automation's 1794 FLEX I/O family, specifically to address the growing demand for intrinsically safe field I/O in process industries during the late 1990s and early 2000s. Early revisions of the series focused on analog signal acquisition (4–20 mA, thermocouple, RTD) with ATEX certification as the primary differentiator. Subsequent hardware revisions introduced improved noise immunity, expanded channel density, and tighter conformance to IEC 60079-11 (intrinsic safety standard). The series operates on a shared backplane with the 1797-BIC (Bus Interface Coupler), which isolates the hazardous-area I/O from the safe-area communication adapter. Compatibility with legacy ControlNet (1794-ACN15) and DeviceNet (1794-ADN) adapters has been maintained across hardware revisions, ensuring backward integration into existing DCS and PLC architectures. As of 2020s, the 1797 series is classified as a mature/end-of-life platform by Rockwell Automation. New installations are directed toward the 1719 Ex I/O series. However, the installed base of 1797 modules in operating facilities remains substantial, and long-term maintenance support — including spare parts sourcing — remains a critical operational requirement for asset owners.

1797 FLEX Ex Full Catalog & Functionalities (SKU List)

Analog Input Modules

• 1797-IE8NF: 8-channel analog current input, 4–20 mA, ATEX/IEC Ex Zone 1 certified, intrinsically safe
• 1797-IE8: 8-channel analog current input module, non-incendive, Class I Div 2 rated
• 1797-IRT8: 8-channel RTD/resistance input, supports Pt100/Pt1000, intrinsically safe
• 1797-ITB16: 16-channel thermocouple/mV input, multi-type TC support, Zone 1 rated
• 1797-IE4: 4-channel analog current input, 4–20 mA, compact form factor, intrinsically safe

Analog Output Modules

• 1797-OE8: 8-channel analog current output, 4–20 mA, intrinsically safe, Zone 1
• 1797-OE4: 4-channel analog current output, 4–20 mA, DIN-rail mount, ATEX certified

Digital Input Modules

• 1797-IB8F: 8-channel digital input, 24 VDC, ATEX Zone 1, intrinsically safe field wiring
• 1797-IB8: 8-channel digital input, non-incendive, Class I Div 2, 24 VDC
• 1797-IB16: 16-channel digital input, 24 VDC, high-density, Zone 2 rated

Digital Output Modules

• 1797-OB8F: 8-channel digital output, 24 VDC, ATEX Zone 1, intrinsically safe
• 1797-OB8: 8-channel digital output, non-incendive, Class I Div 2, 24 VDC

Backplane & Infrastructure

• 1797-BIC: Bus Interface Coupler, isolates hazardous-area backplane from safe-area adapter
• 1797-BICF: Bus Interface Coupler, ATEX Zone 1 rated, for fully certified hazardous installations
• 1797-CEC: Communication Extension Cable, links BIC to remote I/O terminal bases
• 1797-TB3: 3-slot terminal base, field wiring termination for 1797 I/O modules
• 1797-TB3S: 3-slot terminal base with spring-clamp wiring, vibration-resistant installations