It has already been mentioned that a SpaceWire router can act as a data concentrator. Another example of this is shown in Figure 11.

Figure 11 Router as Data Concentrator

Instrument 1 is a high data rate instrument and is connected by direct links to the routers in the prime and redundant data-handling systems. Instruments 2-5 are lower data rate instruments which are, for example, all situated in one area of the spacecraft. To reduce the size of the cable harness the data from Instruments 2-5 are concentrated by a SpaceWire router and sent to the prime or redundant data-handling units over single SpaceWire links.

The advantages of this architecture are:

• Reduced cable mass
• High rate instrument(s) have direct connection to data-handling unit
• Low to moderate rate instruments are connected via concentrating router

The disadvantages of the particular architecture shown in Figure 11 are:

• Have to be aware of potential blocking in router – need to consider traffic on network
• Concentrating Router is not redundant

The concentrating router can be made redundant if required by adding redundant SpaceWire links and interfaces.

This type of architecture is suitable for payload data-handling systems with distributed clusters of instruments which are being served by centralised data-handling unit.