
Product Overview
Accurate temperature measurement is essential for maintaining product quality, process stability, and equipment safety in industrial automation systems. The Allen-Bradley 1746-NT4/B SLC 500 Thermocouple/mV Analog Input Module is a high-performance 4-channel analog input module designed for the SLC 500 PLC platform, providing reliable acquisition of thermocouple and millivolt (mV) signals for process monitoring and control.
The 1746-NT4/B enables direct connection to multiple thermocouple types as well as low-level millivolt input devices, eliminating the need for external signal converters in many applications. Installed in an SLC 500 chassis, the module communicates with the PLC processor through the system backplane, allowing precise temperature and voltage data to be integrated into automation programs.
With compact dimensions of 144.5 × 34.6 × 130.18 mm and a weight of 0.45 kg, the 1746-NT4/B provides a dependable solution for industrial temperature monitoring, furnace control, heat treatment, chemical processing, and manufacturing automation.
Technical Specifications
| Parameter |
Details |
| Manufacturer |
Allen-Bradley |
| Model |
1746-NT4/B |
| Product Type |
SLC 500 Thermocouple/mV Analog Input Module |
| PLC Platform |
SLC 500 |
| Number of Input Channels |
4 |
| Input Signal Types |
Thermocouple and Millivolt (mV) |
| Supported Thermocouple Types |
J, K, T, E, R, S, B, N |
| Input Resolution |
16-bit |
| Cold Junction Compensation |
Built-in Automatic Compensation |
| Data Conversion |
Analog to Digital |
| Backplane Communication |
SLC 500 Backplane |
| Installation |
SLC 500 Chassis |
| Dimensions |
144.5 × 34.6 × 130.18 mm |
| Weight |
0.45 kg |
| Application |
Industrial Temperature and Process Measurement |
Product Features
The 1746-NT4/B is engineered to provide accurate analog signal acquisition in demanding industrial environments.
Key features include:
- Four independent analog input channels
- Direct support for multiple thermocouple types
- Millivolt signal measurement capability
- High-resolution 16-bit analog conversion
- Built-in automatic cold junction compensation
- High measurement accuracy and stability
- Excellent noise immunity for industrial applications
- Seamless integration with SLC 500 PLC systems
Its flexible input capability allows one module to support a wide range of industrial temperature sensing applications.
Working Principle
The 1746-NT4/B converts low-level analog signals from thermocouples or millivolt devices into digital values that can be processed by the SLC 500 PLC.
When a thermocouple detects temperature changes, it generates a small millivolt signal proportional to the measured temperature. The module amplifies this signal, applies automatic cold junction compensation, performs high-resolution analog-to-digital conversion, and transmits the processed data to the PLC processor through the SLC 500 backplane.
The PLC then uses the temperature information for:
- Process temperature control
- Alarm generation
- PID regulation
- Data logging
- Equipment protection
- Production monitoring
This process ensures accurate and reliable temperature measurement throughout industrial operations.
Role in Industrial Automation Systems
The 1746-NT4/B serves as the temperature acquisition interface within industrial control systems.
| Function |
Description |
| Temperature Measurement |
Acquires thermocouple temperature signals |
| Millivolt Measurement |
Processes low-level DC voltage signals |
| Analog Signal Conversion |
Converts analog inputs into digital PLC data |
| Process Monitoring |
Provides real-time temperature information |
| Equipment Protection |
Detects abnormal temperature conditions |
| Process Automation |
Supports automatic temperature control |
Industrial Applications
The Allen-Bradley 1746-NT4/B is widely used in industrial applications requiring accurate temperature and low-voltage signal measurement.
| Industry |
Typical Equipment |
| Steel Industry |
Heat treatment furnaces |
| Petrochemical |
Reactor temperature monitoring |
| Food & Beverage |
Cooking and sterilization systems |
| Pharmaceutical |
Process temperature control |
| Power Generation |
Boiler and turbine monitoring |
| Glass Manufacturing |
Furnace control systems |
| Plastics Industry |
Injection molding machines |
| General Manufacturing |
Industrial heating and cooling equipment |
Its high measurement accuracy makes it ideal for both continuous process industries and discrete manufacturing environments.
Installation and System Integration
Proper installation helps ensure accurate measurements and long-term reliability.
Recommended installation procedures include:
- Install the module into a compatible SLC 500 chassis.
- Verify available backplane power before installation.
- Connect thermocouple or millivolt input wiring according to channel assignments.
- Use appropriate thermocouple extension wire where required.
- Keep analog wiring separated from high-voltage cables to minimize electrical noise.
- Configure input types within the PLC program.
- Verify channel calibration before system operation.
Following these practices helps maximize measurement accuracy and system stability.
Compatible System Components
The 1746-NT4/B integrates with a wide range of SLC 500 automation products.
| Compatible Component |
Function |
| SLC 500 Processor |
Executes temperature control programs |
| SLC 500 Chassis |
Houses the I/O modules |
| Thermocouple Sensors |
Temperature measurement |
| Millivolt Sensors |
Low-level voltage measurement |
| 1746-NO4I Analog Output Module |
Process output control |
| Human Machine Interface (HMI) |
Temperature display and operation |
| Industrial Power Supply |
System power distribution |
Together, these components create a complete industrial temperature monitoring and control system.
Recommended Alternative Models
| Model |
Product Type |
Key Feature |
Typical Application |
| 1746-NT4/B |
Thermocouple/mV Analog Input Module |
Multi-type thermocouple support |
Industrial temperature control |
| 1746-NI4 |
Analog Input Module |
Voltage and current input |
General process measurement |
| 1746-NI8 |
8-Channel Analog Input Module |
Higher analog input density |
Large automation systems |
| 1746-NO4I |
Analog Output Module |
Current output control |
Process regulation |
| 1746-NO4V |
Analog Output Module |
Voltage output control |
Industrial automation systems |
Key Advantages
- Four high-accuracy analog input channels
- Supports multiple thermocouple types and millivolt inputs
- Built-in automatic cold junction compensation
- High-resolution analog-to-digital conversion
- Excellent industrial noise immunity
- Reliable long-term measurement stability
- Easy integration with Allen-Bradley SLC 500 PLC systems
- Ideal for temperature monitoring and process control applications
Technical FAQs
What is the Allen-Bradley 1746-NT4/B used for?
The 1746-NT4/B is designed to acquire thermocouple and millivolt input signals, enabling accurate temperature measurement and process monitoring in SLC 500 PLC systems.
How many input channels does the module provide?
The module provides 4 independent analog input channels, allowing multiple temperature or millivolt signals to be monitored simultaneously.
Which thermocouple types are supported?
The 1746-NT4/B supports common industrial thermocouple types including J, K, T, E, R, S, B, and N, providing flexibility for a wide range of applications.
Does the module include cold junction compensation?
Yes. The module features built-in automatic cold junction compensation, helping maintain accurate thermocouple measurements without additional external hardware.
Conclusion
The Allen-Bradley 1746-NT4/B SLC 500 Thermocouple/mV Analog Input Module is a reliable and versatile analog input solution designed for high-precision temperature and millivolt signal measurement in industrial automation systems.
Featuring 4 independent analog input channels, support for multiple thermocouple types, 16-bit resolution, built-in cold junction compensation, compact dimensions of 144.5 × 34.6 × 130.18 mm, and a weight of 0.45 kg, the module delivers dependable performance in demanding industrial environments.
Whether used in furnace control, petrochemical processing, power generation, pharmaceutical manufacturing, or general process automation, the 1746-NT4/B provides an efficient and accurate solution for temperature monitoring, process optimization, and long-term system reliability.