The Allen-Bradley 1746-NT8, also cataloged as the 1746-NT8 Analog Input Module, operates as a dedicated hardware component for thermocouple and millivolt signal acquisition within the SLC 500 control platform.

Module Identification

The 1746-NT8 is an SLC 500 analog input module designed for temperature measurement applications using thermocouple and millivolt input signals. The module converts field analog signals into digital values for processing by an SLC 500 processor through the chassis backplane.

Hardware Specifications

Process Signal Interface and Data Conversion

The 1746-NT8 receives low-level temperature-related input signals from thermocouple sensors and millivolt devices. The module performs analog-to-digital conversion and transfers processed values through the SLC 500 backplane.

The input architecture supports I/O density scaling within SLC 500 systems by adding analog measurement capability without replacing the processor unit. Proper channel configuration is required to match the selected sensor type and engineering units.

Allen-Bradley SLC 500 analog modules use defined backplane communication structures for deterministic data exchange between I/O modules and controller memory tables.

Industrial Control Platform Characteristics

The SLC 500 platform uses modular chassis architecture with slot-based I/O expansion. The 1746-NT8 communicates through the chassis backplane and follows controller-defined addressing for input data mapping.

For installation in industrial control cabinets, signal wiring separation is required between analog measurement circuits and high-voltage switching conductors. Shielded sensor wiring and proper grounding methods help reduce electrical interference during temperature signal acquisition.

Ordering Information

• 1 x Allen-Bradley 1746-NT8 SLC 500 Analog Input Module
• Module terminal interface included
• Product identification label included
• No programming software or controller CPU included

Field Installation Guidelines

Module Mounting

• Install the module into a compatible Allen-Bradley SLC 500 chassis slot.
• Remove chassis power before inserting or removing the module.
• Verify slot addressing matches the PLC configuration.

Signal Wiring

• Use suitable thermocouple extension wiring for the selected sensor type.
• Keep analog input wiring separated from motor and power circuit conductors.
• Connect sensor polarity according to thermocouple input requirements.
• Avoid parallel routing with high-frequency switching cables.

Grounding Requirements

• Maintain cabinet grounding according to industrial installation practices.
• Connect cable shields using appropriate grounding methods.
• Avoid multiple grounding points that may introduce signal loops.

Frequently Asked Questions

• What type of signals does the 1746-NT8 accept?

  The module accepts thermocouple and millivolt analog input signals for temperature measurement and process monitoring.

• How many input channels are available?

  The 1746-NT8 provides 8 analog input channels within an SLC 500 chassis configuration.

• Is the 1746-NT8 a digital input module?

  No. The module is an analog input device designed for thermocouple and millivolt signal measurement.

• Does the module require a separate power supply?

  The module operates through the SLC 500 chassis power and backplane interface.

• Can the module be installed during operation?

  Module replacement should follow SLC 500 installation procedures with chassis power removed.

• Does the module support standard discrete sensors?

  No. It is designed for analog thermocouple and millivolt signal inputs rather than discrete switching devices.

• How does the module communicate with the PLC?

  The module exchanges converted input data with the processor through the SLC 500 backplane.

• What installation practice is recommended for sensor wiring?

  Shielded wiring, proper grounding, and separation from high-noise conductors are recommended for analog signal stability.