When one end of a SpaceWire link is periodically sending out valid time-codes, the SpaceWire interface at the other end of the link receives the time-codes, checks their validity, updates the time-counter with the new time value and asserts the TICK_OUT signal. The host system attached to this end of the SpaceWire link, receives periodic TICK-OUT signals together with the six-bit time value and the two control-flags. The TICK-OUT signal can be used to raise an interrupt or event in a software-driven node.

If a SpaceWire interface receives a time-code that is not one more than the current value of its time-counter then the time-code is not valid and the interface does not emit a TICK_OUT signal.