***spare part*** SIPLUS S7-1200 SM 1231 RTD based on 6ES7231-5PD30-0XB0 with conformal coating, -25…+70 °C, analog input, 4 AI RTD Module Just like the CPU, the analog input modules are also protected against extreme ambient conditions. Due to the 100% conformal coating they can withstand biologically, chemically and physically active substances, condensation, frost, and corrosive gases. Regardless of the conditions, your analog signals are reliably recorded.