Allen-Bradley 1797-IE8 FLEX Ex 8-Point Analog Input Module

Intrinsically Safe Signal Acquisition for Hazardous Environments

The Allen-Bradley 1797-IE8 functions as a high-precision interface designed specifically for the FLEX Ex™ I/O platform. It enables the safe acquisition of analog signals directly from sensors located in explosive atmospheres without the need for additional external barriers. Because this module features intrinsic safety circuitry, it limits the electrical energy delivered to the field to levels that cannot ignite flammable gases or dust. Consequently, engineers can deploy this module in Class I, Division 1 (Zones 0 and 1) environments, significantly reducing installation costs and cabinet space requirements.

Technical Specifications and Environmental Ratings

• Manufacturer: Allen-Bradley / Rockwell Automation
• Model Number: 1797-IE8
• Module Type: Analog Current Input (Intrinsically Safe)
• Number of Inputs: 8 Non-isolated Channels
• Input Signal Range: 4–20 mA
• Resolution: 16-bit
• Accuracy: 0.1% of Full Scale @ 25°C
• Intrinsic Safety Ratings: Ex ia IIC T4, Class I Div 1, Groups A-D
• Isolation Voltage: 500V AC (between inputs and backplane)
• Power Consumption: 4 Watts @ 9V DC
• Thermal Dissipation: 13.6 BTU/hr
• Weight: 0.9 kg

Advanced Diagnostics and System Reliability

The 1797-IE8 maximizes process uptime by providing continuous monitoring of the field loop integrity. It identifies critical fault conditions such as open-wire detection, underrange, and overrange signals, immediately reporting these anomalies to the controller. Furthermore, the module supports “Removal and Insertion Under Power” (RIUP), which allows technicians to replace the module while the system remains active, provided the area is known to be non-hazardous at that moment or proper safety protocols are followed. Since each of the eight channels is processed with 16-bit precision, the module delivers the granular data required for complex chemical and petrochemical control loops. Moreover, its seamless integration with the 1797-TB3 terminal base ensures robust mechanical and electrical connections in vibration-prone industrial settings.

Primary Industrial Applications

• Petrochemical Refineries: Monitoring flow and pressure transmitters in volatile fuel processing areas.
• Pharmaceutical Manufacturing: Managing precise temperature and level inputs in solvent-rich production suites.
• Oil and Gas Extraction: Interfacing with wellhead instrumentation where explosive methane concentrations may be present.
• Chemical Storage Facilities: Tracking tank levels and hazardous vapor concentrations for safety shutdown systems.