The CB15 terminal board connects to the LabJack U3’s DB15 connector. It provides convenient screw terminal access to the 12 digital I/O available on the DB15 connector. The CB15 is designed to connect directly to the LabJack, or can connect via a standard 15-line 1:1 male-female DB15 cable. All I/O on the DB15 are fully functional as-is … the CB15 simply breaks them out to screw terminals and is completely optional.