A system for adjusting a serial communications link includes a system under test including at least one transmitter and at least one receiver coupled together via a serial data communications link, wherein at least one of the transmitter and the receiver has at least one tunable parameter, at least one controller coupled to at least one of a transmitter and a receiver via a joint test action group JTAG interface, and logic configured to adjust the at least one tunable parameter to optimize a performance of the serial data communications link.