SIPLUS S7-300 SM321 16DI/120/230VAC based on 6ES7321-1FH00-0AA0 with conformal coating, -40…+70 °C, digital input isolated 16 DI, 120/230 V AC, 1x 20-pole Just like the CPU, the digital 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 digital signals are reliably recorded.