On the internal sync-bus clock and trigger information are exchanged between the boards. All connected boards are using the same clock and trigger. One board is defined to be the master board and generates clock for itself and the other boards. This board or another board generates the trigger for all connected boards. When using this kind of synchronisation there is a fixed phase delay between adjacting boards of about 500 ps. Another alternative without having this phase delay is the star hub. It allows to connect up to 16 boards of the MI series together.