Siemens 6ES7231-4HD32-0XB0 is an SM1231 four-channel analog input expansion module for SIMATIC S7-1200 controllers, designed to extend the PLC's ability to read analog sensors in industrial automation. Each of the four inputs supports either 0-20 mA / 4-20 mA current signals or configurable voltage ranges of ±10 V, ±5 V, and ±2.5 V, with a 12-bit plus sign ADC providing up to 13-bit effective resolution per channel. The module is powered by 24 V DC and integrates with S7-1200 systems to convert sensor signals into digital values for monitoring, control, and data logging tasks.
