SpaceWire is a data-handling network for use on-board spacecraft, which connects together instruments, mass-memory, processors, downlink telemetry, and other on-board sub-systems [1]. SpaceWire is simple to implement and has some specific characteristics that help it support data-handling applications in space: high-speed, low-power, simplicity, relatively low implementation cost, and architectural flexibility making it ideal for many space missions. SpaceWire provides high-speed (2 Mbits/s to 200 Mbits/s), bi-directional, full-duplex data-links, which connect together SpaceWire enabled equipment. Data-handling networks can be built to suit particular applications using point-to-point data-links and routing switches.

Since the SpaceWire standard was published in January 2003, it has been adopted by ESA, NASA, JAXA and RosCosmos for many missions and is being widely used on scientific, Earth observation, commercial and other spacecraft. High-profile missions using SpaceWire include: Gaia, ExoMars rover, Bepi-Colombo, James Webb Space Telescope, GOES-R, Lunar Reconnaissance Orbiter and Astro-H.

The development and testing of the SpaceWire links and networks used on these and many other spacecraft currently under development, requires a comprehensive array of test equipment. In this paper the requirements for test equipment fulfilling key test functions are outlined and then equipment that meets these requirements is described. Finally the all-important software that operates with the test equipment is introduced.

SpaceWire-D is a protocol that provides deterministic data delivery over an existing SpaceWire network [1]. It allows SpaceWire networks to be used for time-critical avionics control applications and for asynchronous payload data handling.

SpaceWire-D uses the SpaceWire Remote Memory Access Protocol (RMAP) [2] to provide the basic communication mechanism: transactions that can read or write to memory in a remote target node. These transactions are executed by an initiator, with the initiator sending the RMAP command, a target receiving, executing and replying to the command, and the initiator receiving the reply from the target, which contains any data read from the target or is an acknowledgement to a write command.

To provide determinism the network bandwidth is split into a series of time-slots. One or more initiators are allowed to send a group of transactions in a particular time-slot, provided that transactions from different initiators do not use the same network resources, i.e. common SpaceWire links on the paths from the initiators to the target devices being accessed. The group of transactions executed in a particular time-slot must complete before the end of the time-slot, or a fault will be signalled. This restriction avoids a group of transactions from disrupting the transactions in the next time-slot, if they were to overrun their time-slot.