What this spare part fits
The Siemens 6ES7231-0HC22-0XA0 is the EM 231 analog input module for the S7-22X CPU family — a spare part, not a current-production expansion module. It provides 4 differential analog inputs, each configurable for 0-10V DC, with a 12-bit converter and a conversion time of 250 µs per channel.
The 12-bit resolution (with overrange, including sign) means the module digitizes the analog signal into 4096 steps, plus sign for bipolar ranges. The input resistance is 10 MΩ across all voltage and current ranges, so it loads the sensor minimally. The destruction limits are 30 V for voltage inputs and 32 mA for current inputs — exceeding those damages the input stage. The module draws up to 20 mA from the backplane bus at 5 V DC and up to 60 mA from the load voltage L+ (without load). Power loss is 2 W typical.
The lifecycle stage is current, meaning Siemens still lists it as an active spare part for the S7-200 platform.