SIPLUS S7-300 SM 321-20-pin. based on 6ES7321-1BH02-0AA0 with conformal coating, -40.+70°C, digital input isolated 16 DI, DC 24V, 1x 20-pin Like the CPU, the digital input modules are also protected against extreme environmental conditions. Thanks to the 100% conformal coating, they withstand biological, chemical and mechanically active substances, condensation, frost and harmful gases. No matter what the conditions - your digital signals are reliably recorded.