Allen Bradley 1746-NI8 Analog Input Module

The Allen-Bradley 1746-NI8 is an analog input module designed for use in the SLC 500™ modular system. 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.

The 1746-NI8 module receives power from the SLC 500 chassis backplane, drawing 200 mA at 5V DC and 100 mA at 24V DC. It employs a successive approximation, switched capacitor A/D conversion method, complemented by a low-pass digital filter with selectable filter frequencies ranging from 1 Hz to 75 Hz, ensuring accurate and stable signal processing. This module also features continuous autocalibration to maintain accuracy over time.

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.