"COMPACT FLASH CARD: 1784-CF128; COMMUNICATION OPTIONS: ETHERNET/IP, CONTROL NET, DEVICE NET; SERIAL COMMUNICATION PORT: 1RS-232 PORT; THE 1768-L4X CONTROLLER COMBINES BOTH A 1768 BACKPLANE AND A 1769 BACKPLANE. THE 1768 BACKPLANE SUPPORTS THE 1768 POWER SUPPLY, AND A MAXIMUM OF FOUR 1768 MODULES. THE 1769 BACKPLANE SUPPORTS 1769 MODULES."