Siemens 6ES7221-1BH50-0XB0 Digital Input Module. Siemens 6ES7221-1BH50-0XB0 is the exact manufacturer order number for a digital input module in the SIMATIC S7-1200 portfolio. Siemens describes this exact reference as: SIMATIC S7-1200 G2: SM 1221 digital input, 16 DI; inputs: 16x DI 24 V DC sink/source. The verified manufacturer lifecycle record is PM300: Active Product.