SM331 EXTEND MODULE (6ES73317KF020AB0) SIMATIC S7-300, ANALOG INPUT SM 331, OPTICALLY ISOLATED, 8AI, RESOLUTION 9/12/14 BITS, U/I/THERMOCOUPLE/RESISTANCE INTERRUPT, DIAGNOSTICS; 1X20PIN REMOVE/INSERT W. BACKPLANE BUS AND SIMATIC S7-300, FRONT CONNECTOR(6ES73921BJ000AA0) FOR SIGNAL MODULES WITH SPRING CONTACTS, 20-PIN