Four thermocouple inputs, wide temperature range
The Siemens 6AG1231-5QF32-4XB0 is a SIPLUS variant of the SM 1231 analog input module for the S7-1200 system, providing four analog inputs specifically for thermocouple measurement. It covers thermocouple types J, K, T, E, R, S, B, N, C, and TXK/XK(L) per GOST, with a voltage measurement range of ±80 mV. The integrating measurement principle and built-in cold-junction compensation make it a direct fit for temperature loops in process and HVAC applications.
Rated for the cold and the heat
That -40 °C floor means it can live in a refrigerated warehouse or an unheated enclosure in a northern climate without a heater. The 70 °C ceiling covers most cabinet interiors near motors or ovens, though the 1.5 W typical power dissipation means the module itself adds little heat to the enclosure.
Diagnostics and wiring
The module reports wire-break and diagnostic alarms, and the supply voltage is monitored on-board. It requires a front connector (sold separately) and draws 40 mA from the 24 VDC backplane supply. The 45 mm width fits a standard S7-1200 rack slot; the IP20 rating means it belongs in a clean, dry enclosure, not on the machine frame.