The SIEMENS6ES7231-4HD32-0XB0 is an analog input module for the SIMATIC S7-1200 series. It supports four analog signal inputs and is compatible with ± 10V, ± 5V, ± 2.5V, or 0-20 mA/4-20 mA signals with 13-bit ADC resolution. It is widely used in automation control system, process control and other fields.