Advantechs eki 1521 features two independent ethernet ports and mac addresses to provide a redundant network mechanism to guarantee ethernet network reliability eki 1521 is a serial device servers that connects rs 232422485 serial devices such as plc meters sensors and barcode readers to an ip based ethernet lan the eki 1521 allows nearly any device with serial ports to connect and share an ethernet network various operations are possible com port redirection virtual comport tcp se