Siemens 6ES7231-4HD32-0XB0 SIMATIC S7-1200 SM 1231 Analog Input Module. SIMATIC S7-1200, Analog input, SM 1231, 4 AI, +/-10 V, +/-5 V, +/-2.5 V, or 0-20 mA/4-20 mA, 12 bit+sign (13 bit ADC). It belongs to SM 1231 analog input modules. Recorded manufacturer technical characteristics include Alarms: Yes; Analog inputs: 4; IP Protection: IP20; Integration time: Parametrizable; Loss power (typ.): 1.5 W; Rated voltage (DC): 24 V; Diagnostic function: Yes; Input current ranges: 0-20 mA, 4-20 mA.