6ES7321-1BH02-0AA0 PLC S7-300, Digital Input SM 321, Isolated, 16 DI, 24 V DC, 1x 20-Pole: Amazon.com: Industrial & Scientific
SIEMENS 6ES7 321-1BH02-0AA0 DIGITAL INPUT MODULE - Platinum International
6ES7321-1BH02-0AA0 Siemens | Siemens SIMATIC S7-300 Series Series Digital Input Expansion Module for Use with SIMATIC S7-300 Series, Digital, 24 V | 453-2517 | RS Components