Allen Bradley 1746-NI8 Analog Input Module

The Allen-Bradley 1746-NI8 is an analog input module designed for the SLC 500 series programmable controllers, providing reliable and accurate data acquisition for various industrial applications. This module provides eight input channels, capable of accepting a variety of input types, including ±10V DC, 0 to 10V DC, 0 to 5V DC, 1 to 5V DC, 0 to 20 mA, 4 to 20 mA, and ±20 mA. The module is engineered to convert these analog signals into digital values that can be processed by the SLC 500 system, making it suitable for applications requiring precise analog signal measurement and control.

Technical Specifications

• Manufacturer: Allen Bradley (Rockwell Automation)

• Part Number: 1746-NI8

• Module Type: Analog Input Module

• Input Type: Voltage or Current

• Number of Channels: 8 single-ended inputs

• Input Ranges:

  • Voltage: ±10V, 0–10V

  • Current: 4–20 mA, 0–20 mA

• Resolution: 16-bit

• Backplane Current Draw: 95 mA at 5V DC, 85 mA at 24V DC

• Input Impedance:

  • Voltage: >1 MΩ

  • Current: 250 Ω

• Conversion Time: 400 ms per channel

• Accuracy: ±0.1% full scale at 25°C

• Isolation Voltage: 500V AC (channel-to-backplane, channel-to-channel)

• Operating Temperature: 0°C to 60°C (32°F to 140°F)

• Slot Width: Single-slot

• Chassis Compatibility: SLC 500 series

Key Features

• Supports both voltage and current analog input signals

• High-resolution 16-bit A/D conversion for precise data acquisition

• Software-selectable input ranges for application flexibility

• Per-channel configuration allows customization for mixed signal types

• Integrated diagnostic functions for channel error detection

• Compact single-slot design for efficient rack space usage

• Designed for integration with SLC 500 modular systems

Compatible Components & Accessories

• Compatible Chassis: Allen Bradley SLC 500 Series (1746-A4, 1746-A7, 1746-A10, 1746-A13, 1746-A17)

• Compatible Processors: SLC 5/02, 5/03, 5/04, and 5/05 CPUs

• Terminal Blocks: 1746-TBCH, 1746-TBS

• Configuration Software: RSLogix 500, Studio 5000 (legacy integration)

• Wiring Accessories: Shielded twisted pair cable recommended for current loops

Industry Applications

• Water and wastewater treatment facilities

• Industrial automation and manufacturing lines

• Oil and gas monitoring and control systems

• Food and beverage process monitoring

• HVAC and building automation

• Power and energy management systems

Installation & Maintenance Notes

• Ensure correct slot orientation and secure connection within the SLC chassis

• Use proper grounding techniques and shielding to minimize electrical noise

• Configure each channel individually using RSLogix 500 for voltage or current inputs

• Allow adequate clearance for airflow to maintain temperature operating range

• Perform periodic inspection of wiring and module integrity in harsh environments

• Firmware updates and diagnostics can be managed through the system processor

Installation of the 1746-NI8 is flexible, allowing it to be placed in any I/O module slot of the SLC 500 modular chassis, except for slot 0, which is reserved for processor or adapter modules. It is important to consider heat and noise factors when positioning the module; it should be placed away from high-noise sources such as AC motor drives and modules that generate significant heat. The module operates within a temperature range of 0°C to 55°C, or up to 60°C if placed in the rightmost slot of the chassis.

The module includes a removable 18-position terminal block for ease of wiring and maintenance. The terminal block accommodates shielded, twisted-pair cables to minimize noise interference, ensuring reliable signal transmission. The 1746-NI8 is also designed with electrostatic discharge protection, featuring guidelines for safe handling to prevent damage to its semiconductor components.

Electrical specifications of the 1746-NI8 highlight its robust performance, including a common-mode rejection of at least 75 dB at DC and 100 dB at 50/60 Hz, and an input resolution of 1 mV or 1 µA. Its high accuracy, with a maximum error of ±0.1% for voltage inputs and ±0.05% for current inputs, makes it a reliable choice for precise analog measurements in industrial automation applications. Additionally, the module is UL listed, CSA approved, and CE compliant, underscoring its suitability for a wide range of environments, including hazardous locations classified as Class 1, Division 2.