The Allen-Bradley 1746-NR4, also cataloged as the 1746-NR4 Resistance Input Module, operates as a dedicated hardware component for RTD and resistance signal acquisition within SLC 500 controller systems. The module converts analog resistance values into digital data for PLC processing.

Model Identification

The 1746-NR4 is an SLC 500 analog input module designed for RTD and resistance measurement applications. The available catalog variations include:

• 1746-NR4 standard catalog number
• 1746-NR4/A hardware revision
• 1746-NR4/B hardware revision

Hardware Specifications

Industrial Control Integration Characteristics

The 1746-NR4 operates within the SLC 500 backplane architecture and transfers converted analog measurement data to the processor through the chassis bus. The module supports I/O density scaling by providing four analog resistance input channels in a single slot.

The module backplane interface manages communication between the analog input circuitry and the SLC processor. Proper firmware compatibility between the processor and I/O configuration is required when integrating replacement modules into existing control systems.

Installation and Wiring Notes

• Install the module in an SLC 500 chassis slot other than Slot 0.
• Connect RTD or resistance sensors according to the terminal wiring configuration defined for the module.
• Separate analog signal wiring from high voltage power conductors to reduce electrical interference.
• Use shielded instrumentation cable where required by the installation environment.
• Connect cable shields according to the system grounding practice.
• Verify module power loading before installation into a configured chassis.

Ordering Information

• 1 x Allen-Bradley 1746-NR4 RTD / Resistance Input Module
• 1 x Protective industrial packaging
• Documentation availability depends on supply configuration

Field Installation Guidelines

• Confirm the SLC 500 chassis power capacity before adding the module.
• Remove chassis power before inserting or removing the module.
• Verify terminal wiring polarity and sensor type before startup.
• Check backplane current loading when multiple analog modules are installed.
• Maintain separation between analog input wiring and switching output circuits.

Frequently Asked Questions

• What type of signals does the 1746-NR4 accept?

The module accepts RTD and resistance input signals and converts measured resistance values into PLC-readable analog data.

• How many input channels are available on the 1746-NR4?

The module provides 4 analog input points for RTD and resistance measurement applications within an SLC 500 chassis.

• Can the 1746-NR4 be installed in Slot 0?

No. The module can be installed in any SLC 500 chassis slot except Slot 0, which is reserved for the processor module.

• What is the backplane current requirement?

The module requires 50 mA backplane current according to the provided technical specification.

• What is the maximum power consumption of this module?

The maximum power consumption is 1.5 W, consisting of 0.3 W from 5 VDC and 1.2 W from 24 VDC sources.

• Does the module communicate through EtherNet/IP or DeviceNet?

No. The 1746-NR4 communicates through the SLC 500 chassis backplane connection to the installed processor.

• What installation precautions are required for analog wiring?

Analog sensor wiring should be separated from power conductors and installed using appropriate grounding and shielding practices.

• Is hot insertion supported for the 1746-NR4?

The module should be installed or removed with chassis power removed unless the specific SLC 500 configuration documentation permits otherwise.