Product Overview

The Allen-Bradley 1797-IE8 is a high-precision, 8-channel analog current input module specifically engineered for the FLEX Ex™ I/O system. This module is designed to interface with field devices located in hazardous areas, providing intrinsic safety (IS) protection without the need for external barriers. By integrating the IS barrier functionality directly into the module hardware, the 1797-IE8 simplifies cabinet architecture while ensuring compliance with stringent explosive atmosphere standards, including Ex ia and Class I, Division 1.

Supporting standard 4-20 mA current loops, the 1797-IE8 converts analog process variables into high-resolution 16-bit digital data. It is a critical component for oil and gas, chemical processing, and pharmaceutical applications where flammable gases or vapors are present and measurement accuracy is paramount for process safety and efficiency.

High-Resolution Measurement and Safety Architecture

The 1797-IE8 combines laboratory-grade measurement precision with ruggedized hardware for volatile environments.

• Intrinsically Safe Design: Eliminates the risk of electrical sparking by limiting the energy available to the hazardous area, certified for use in Zone 1 and Zone 2 (ATEX/IECEx) as well as North American Class I, II, and III locations.

• 16-Bit Resolution: Provides highly granular data conversion for precise monitoring of pressure, flow, and level sensors, supporting an accuracy of 0.1% of full scale.

• Non-Isolated Channels: Features eight high-speed current inputs sharing a common return, optimized for high-density sensor arrays.

• Configurable Input Filtering: Allows users to adjust the software-selectable digital filter to mitigate the effects of industrial noise and signal transients.

• Standardized Integration: Mounts onto specialized 1797-TB3 or 1797-TB3S terminal bases, facilitating "Removal and Insertion Under Power" (RIUP) even in hazardous zones when appropriate safety protocols are followed.

Technical Specifications

• Manufacturer: Allen-Bradley (Rockwell Automation)

• Model Number: 1797-IE8

• Input Type: Analog Current (4-20 mA)

• Number of Inputs: 8 Channels (Non-isolated)

• Resolution: 16 bits

• Intrinsic Safety Rating: Ex ia IIC T4, Class I Div 1 Groups A-D

• Input Impedance: < 65 ohms

• Accuracy: 0.1% Full Scale @ 25°C

• Power Consumption: 4 Watts @ 9V DC (from FlexBus)

• Thermal Dissipation: 13.6 BTU/hr

• Operating Temperature: -20°C to 70°C (-4°F to 158°F)

• Dimensions: 3.5 x 13.0 x 14.5 cm

• Weight: 0.9 kg (1.98 lbs)

Diagnostic Monitoring and Maintenance

The 1797-IE8 includes advanced firmware-based diagnostics that continuously monitor the integrity of the field wiring and the health of the module.

• Wire-Break Detection: Instantly identifies open-circuit conditions in the 4-20 mA loop, allowing the controller to trigger "fail-safe" states.

• Range Validation: Detects and flags over-range and under-range signals, identifying potential sensor calibration drift or mechanical failure.

• LED Status Array: Front-panel indicators provide local visual confirmation of module power, communication status, and individual channel faults.

• Proactive Troubleshooting: Diagnostic data is transmitted via the FLEX Ex adapter to the central PLC, enabling remote monitoring of field-side health without entering the hazardous area.