Product Overview of the Allen-Bradley 1794-IF8IH

The Allen-Bradley 1794-IF8IH belongs to the Flex I/O 1794 series. This module reads analog signals from HART-enabled field devices. It features eight isolated input channels for noise rejection. Each input is single-ended and fully isolated from others. The module carries North American Hazardous Location approvals. This certification allows safe use in explosive environments. Factory calibration ensures accurate measurements out of the box. You can also perform field calibration if needed.

Technical Specifications

• Brand: Allen-Bradley / Rockwell Automation
• Part Number: 1794-IF8IH
• Product Type: Flex I/O HART Analog Input Module
• Number of Inputs: 8 Isolated, Single-Ended Inputs
• Conversion Type: Sigma-Delta
• Unipolar Resolution: 16 bits
• Bipolar Resolution: 15 bits plus sign
• External DC Voltage Range: 19.2 to 31.2 Volts DC
• AC Ripple Tolerance: 5%
• Flexbus Current: 80 mA at 5 Volts DC
• Maximum Power Dissipation: 4.8 Watts at 31.2 Volts DC
• Maximum Thermal Dissipation: 16.4 BTU/hour at 31.2 Volts DC
• Operating Temperature: 32 to 131 °F (0 to 55 °C)
• Enclosure Type: Open
• Dimensions (H x W x D): 3.7 x 3.7 x 2.6 inches (94 x 94 x 66 mm)
• Outputs: None (Input only module)

Resolution and Conversion Performance

The 1794-IF8IH uses high-precision Sigma-Delta conversion. This method provides excellent noise rejection for analog signals. The unipolar resolution reaches 16 bits for positive signals. The bipolar resolution reaches 15 bits plus a sign bit. This configuration covers both positive and negative analog values. The module handles a wide range of industrial sensors. You can connect pressure transmitters and flow meters easily. Temperature sensors and level transmitters also work well. The high resolution ensures accurate process variable readings.

Terminal Base Compatibility and Installation

The Allen-Bradley 1794-IF8IH mounts on specific terminal bases. Use the 1794-TB3 or 1794-TB3S terminal base units. These bases provide the necessary connections for analog signals. The wire size depends on your chosen terminal base. Always use shielded wire for all analog signal connections. The signal ports fall under wiring category 2 requirements. The power ports fall under wiring category 3 requirements. Proper shielding reduces electrical noise interference significantly. Follow these guidelines for reliable analog measurements.

Power Requirements and Environmental Specifications

This 1794-IF8IH module requires an external DC power supply. The acceptable voltage range is 19.2 to 31.2 Volts DC. The supply can tolerate up to 5% AC ripple content. The Flexbus draws 80 mA at 5 Volts DC from the backplane. Maximum power dissipation reaches 4.8 Watts at high voltage. Thermal dissipation peaks at 16.4 BTU per hour. The module operates safely between 32 and 131 degrees Fahrenheit. The open enclosure requires installation inside a protective cabinet. This cabinet must keep out dust and conductive contaminants.

HART Communication Capabilities

The 1794-IF8IH supports HART protocol on all eight channels. HART stands for Highway Addressable Remote Transducer. This protocol superimposes digital signals on analog 4-20 mA loops. You can access additional device data from smart transmitters. This includes diagnostic information and secondary variables. You can also change transmitter configuration parameters remotely. The module handles both the analog value and digital HART data. This dual capability provides more process information than standard analog modules.

Calibration and Maintenance

The 1794-IF8IH leaves the factory fully calibrated. This factory calibration meets most application accuracy requirements. You can perform field calibration for special applications. Field calibration adjusts the module to specific sensor characteristics. The process requires accurate calibration standards and equipment. Follow the official Allen-Bradley calibration procedure carefully. Regular calibration checks ensure long-term measurement accuracy. Keep calibration records for quality compliance purposes.

Package Contents

• One (1) Allen-Bradley 1794-IF8IH Flex I/O HART Analog Input Module
• One (1) Installation Instructions Sheet

Common FAQs for the 1794-IF8IH

1. How many analog inputs does the 1794-IF8IH provide?

The 1794-IF8IH provides eight isolated analog inputs. Each input is single-ended and fully isolated from the others. This design prevents ground loops between different field devices.

2. What terminal bases work with the 1794-IF8IH module?

The 1794-IF8IH works with the 1794-TB3 or 1794-TB3S terminal bases. These bases provide the correct connections for eight analog inputs. Always use shielded wiring for best signal quality.

3. What is the resolution of the 1794-IF8IH converter?

The 1794-IF8IH uses a Sigma-Delta converter with 16-bit unipolar resolution. The bipolar resolution reaches 15 bits plus a sign bit. This high resolution ensures accurate process measurements.

4. Does the 1794-IF8IH support HART communication?

Yes, the 1794-IF8IH fully supports HART protocol on all eight channels. You can read digital data from smart transmitters. The module also allows configuration changes to HART devices.

5. What is the operating temperature range for the 1794-IF8IH?

The 1794-IF8IH operates safely from 32 to 131 degrees Fahrenheit. This range equals 0 to 55 degrees Celsius. The module has an open enclosure for cabinet mounting only.