SM331 EXTEND MODULE (6ES73317KB020AB0) SIMATIC S7-300, ANALOG INPUT SM 331, OPTICALLY ISOLATED, 2 AI, 9/12/14 BITS RESOLUTION, U/I/THERMOCOUPLE/RESISTANCE, INTERRUPT, DIAGNOSTICS, 1 X 20 PIN, REMOVE/INSERT W. BACKPLANE BUS AND SIMATIC S7-300, FRONT CONNECTOR(6ES73921BJ000AA0) FOR SIGNAL MODULES WITH SPRING CONTACTS, 20-PIN