The Allen-Bradley Bulletin 931 series provides a comprehensive signal conditioning platform for industrial automation, converting, isolating, and amplifying analog signals between field devices and control systems. Built for DIN rail mounting, the series spans four sub-families — Nano (931N), Smart (931S), HART (931H), and Universal (931U) — each delivering 3-way galvanic isolation at 2.5 kV to protect PLC and DCS inputs from ground loops, transients, and electrical noise.

What signal types does the 931 series accommodate?

Standard current (0/4–20 mA, ±10/±20 mA), voltage (0–10 V, ±5/±10 V), thermocouple (B, E, J, K, L, N, R, S, T, W3, W5), RTD (PT100, PT1000, Ni100, Ni1000), potentiometer, resistance, frequency (up to 100 kHz), and NAMUR sensor inputs are all supported across the series. Outputs include 0/4–20 mA and 0–10 V, configurable via DIP switches without calibration.

How do the sub-families compare?

The 931N Nano delivers 0.05% accuracy in a 6 mm-wide housing with dedicated models for analog, thermocouple, RTD, and universal conversion. The 931S Smart adds frequency conversion, Hall-effect current monitoring, and output loop splitting at 0.1–0.2% accuracy. The 931H HART provides transparent HART communication pass-through with a 2 ms response time. The 931U Universal features PC-programmable universal input covering all signal types with configurable relay outputs for alarm functions. A power bus DIN connector option allows one feed module to supply up to 75 devices, reducing wiring complexity.

What environmental and safety certifications apply?

The 931 series carries cULus Class I Division 2, CE, ATEX, IECEx, FM, DNV-GL, KC, and RCM certifications, qualifying it for hazardous location installations and global deployment. Operating temperature spans −25 °C to +70 °C, with screw terminal connections angled for easy field wiring.