Siemens 6ES72231PH320XB0 SIMATIC Digital I/O Module. Siemens Digital I/O Module, 8 Inputs, 8 Outputs, 10 ms Off to On/On to Off Step Response, 24 VDC, 4 mA, Front Connector Terminal, -20 to 60 deg C, 100 mm H x 45 mm W x 75 mm D Dimensions. Additional Description: SIEM-6ES72231PH320XB0 DIGITAL I/O SM 1223, 8DI/8DO. Catalog Description: SIMATIC s7-1200, digital i/o sm 1223, 8di / 8do, 8di DC 24 V, sink/source, 8do,relay 2a.