Allen-Bradley 1746-INT4 Isolated Analog Input Module

Allen-Bradley 1746-INT4 is a four-channel isolated thermocouple/millivolt analog input module designed for the SLC 500 backplane. It accepts thermocouples of J, K, T, E, R, S, B, N, C, and D types as well as low-level millivolt signals, with each channel isolated from the others and from the backplane to minimize noise and cross‑channel interference. The module provides 16-bit resolution per channel, a sigma-delta ADC, and an 8 Hz channel bandwidth with a 500 ms update time, enabling stable temperature measurements for process control. Isolation ratings include 1000 V transient and 150 V AC continuous between channels and to the backplane, supporting rugged industrial environments; common‑mode rejection is better than 120 dB at 50/60 Hz with a 1 kΩ imbalance. It occupies any I/O slot except slot 0 in the SLC 500 chassis, and draws about 110 mA from a 5 V supply or 85 mA from a 24 V supply, with a maximum power of 0.6 W. Calibration is typically yearly if required. This module is commonly used for temperature monitoring and other low-voltage sensor measurements where isolated inputs improve accuracy in noisy settings.