6ES7288-1ST20-0AA1/6ES7288-1ST20-0AA0 Siemens CPU ST20, DC/DC/DC, 12DI/8DO SIMATIC S7-200 SMART, CPU ST20, standard CPU, DC/DC/DC, onboard I/O: 12 DI 24 V DC; 8 DQ 24 V DC; power supply: DC 20.4 - 28.8 V DC, program/data memory 20 KB web server support