Allen-Bradley 1771-NT2/C 8-Channel Isolated Thermocouple/mV Input Module
Product Overview
The Allen-Bradley 1771-NT2/C is an 8-channel isolated thermocouple/mV analog input module for the PLC-5 platform. Originally manufactured by Rockwell Automation, it allows a PLC-5 processor to read temperatures directly from just about any thermocouple type as well as generic millivolt signals from sensors such as pyrometers.
Key Specifications
Model: 1771-NT2/C (Series C revision)
Family: PLC-5 N-Series Analog I/O
Input Channels: 8 isolated differential inputs
Input Ranges: -5.5 to 56.0 mV (software-selectable via channel)
Supported Thermocouple Types: B, C, E, J, K, N, R, S, T
Input Impedance: 200 kΩ (minimum)
Update Time: 25 ms (maximum)
Resolution: 16-bit
Performance and Accuracy
The 16-bit resolution provides high precision for temperature monitoring, which is crucial for ovens, kilns, and extrusion processes. The 8 channels are isolated from each other and from the backplane, eliminating ground loop errors common in long-distance thermocouple runs.
Configuration and Industrial Applications
Configuration is performed through the PLC’s configuration words, allowing the user to set the thermocouple type per channel. Applications include industrial furnace temperature monitoring, plastic injection molding barrel control, heat-treat ovens, and drying systems.
Conclusion
The Allen-Bradley 1771-NT2/C provides a robust, highly functional solution for adding direct thermocouple temperature reading to legacy PLC-5 control systems.
