Siemens 6ES72231PL320XB0 SIMATIC Digital I/O Module. Siemens Digital I/O Module, 16 Inputs, 16 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 70 mm W x 75 mm D Dimensions. Additional Description: SIEM-6ES72231PL320XB0 DIGITAL I/O SM 1223, 16DI/16DO. Catalog Description: SIMATIC S7-1200, DIGITAL I/O SM 1223, 16DI / 16DO, 16DI DC 24 V, SINK/SOURCE, 16DO, RELAY 2A.