Product Overview
When your SLC 500 system needs accurate temperature or millivolt measurement, the Allen-Bradley 1746-NT8 delivers dependable eight-channel analog input performance. This Thermocouple/mV Analog Input Module accepts J, K, T, E, S, R, B, and N thermocouples plus ±50 mV and ±100 mV signals, converting them to digital values for any SLC 500 processor. The 1746-NT8 is built for both fixed and modular SLC 500 chassis, making it a versatile choice for industrial automation upgrades.
Technical Specifications
The Allen-Bradley 1746-NT8 offers robust specifications designed for precise temperature monitoring in demanding environments.
| Parameter |
Value |
| Manufacturer |
Rockwell Automation |
| Brand |
Allen-Bradley |
| Part Number |
1746-NT8 |
| Series |
SLC 500 |
| Module Type |
Thermocouple/mV Analog Input Module |
| Number of Inputs |
8 |
| Backplane Current (5V) |
120 mA |
| Backplane Current (24V) |
70 mA |
| Backplane Power Consumption |
2.28 W max (0.6W @ 5V, 1.68W @ 24V) |
| Thermocouple Types |
J, K, T, E, S, R, B, N |
| mV Input Ranges |
±50 mV, ±100 mV |
| Resolution |
16 bits in, 14 bits out |
| Update Time |
356 ms – 4.05 s |
| Step Response |
60 ms in, 2.5 ms out |
| Open Circuit Detection |
Zero, Upscale, Downscale |
| I/O Chassis Location |
Any slot except Slot 0 |
| Operating Temperature |
0 to 60 °C |
| Storage Temperature |
-40 to 85 °C |
| A/D Conversion Method |
Sigma-delta modulation |
Industry Applications
The Allen-Bradley 1746-NT8 excels in applications where precise temperature monitoring is critical. In a plastic injection molding plant, the 1746-NT8 monitors eight thermocouples across barrel zones, ensuring melt temperatures stay within tolerance. A food processing facility uses the 1746-NT8 to track pasteurization temperatures, relying on its fast update time to catch deviations quickly. For a chemical batch reactor, the 1746-NT8 provides the isolation and accuracy needed for safe exothermic reaction control.
Installation & Setup Guidance
Installing the Allen-Bradley 1746-NT8 is straightforward. For modular SLC 500 systems, place the module in any slot except Slot 0, which is reserved for the processor or communication adapter. For fixed style systems, use a 1746-A2 chassis. Connect thermocouple or mV signals using the included 1746-RT34 removable terminal block, which also carries two cold-junction compensation sensors for accurate readings. Ensure input devices have impedance below 100 ohms to maintain accuracy. The module performs automatic self-calibration every two minutes after power-up, reducing manual maintenance.
Maintenance & Reliability
Routine maintenance for the 1746-NT8 is minimal. Check the nine green LED indicators periodically to confirm channel and module status. Keep the chassis environment within 0–60 °C and 5–95% humidity without condensation to ensure long-term reliability. The module's protective features, including input overvoltage protection at ±30V DC and circuit isolation tested at 500V DC, help prevent damage from transients. These features reduce downtime and extend service life, offering strong return on investment for critical temperature monitoring.
Compatibility & Integration
The Allen-Bradley 1746-NT8 integrates seamlessly with SLC 500 processors including SLC 5/01, 5/02, 5/03, 5/04, and 5/05. It supports engineering units, Scaled for PID, and Proportional counts data formats, with Scaled for PID being the most suitable for thermocouple and mV signals. The module reports open circuit, under-range, over-range, and channel errors via bits accessible to HMI and SCADA systems, enabling proactive process monitoring.
Selection Guide & Purchasing Advice
Before purchasing the Allen-Bradley 1746-NT8, verify your system's backplane current capacity: the module draws 120 mA at 5V DC and 70 mA at 24V DC. Confirm that your chassis type (fixed or modular) accepts this module and that you have the 1746-RT34 terminal block (included). For reliable sourcing and quick delivery, PLC Source PRO offers genuine Allen-Bradley 1746-NT8 modules with full technical support.