SpaceWire control codes in SpaceWire, GigaSpaceWire and SpaceFibre networks

Important tasks for any on-board communication network are time synchronization (devices work synchronization) and transmission of low-frequent hard real-time signals, alarm and critical commands. In the SpaceWire standard there are time-codes and distributed interrupts propagation mechanisms for these purposes. The SpaceFibre is a very high-speed serial link for on-board communication; it carries SpaceWire packets over virtual channels. For broadcast propagation of control information SpaceFibre provides the broadcast messages service which may be considered as similar to SpaceWire time-codes for every virtual channel. The GigaSpaceWire has been developed to enhance link characteristics for SpaceWire networks. In the paper we consider transmission of SpaceWire control codes through the communication onboard network where SpaceWire, GigaSpaceWire and SpaceFibre technology are used together; comparison of SpaceWire control codes (distributed interrupts and time-codes with SpaceFibre broadcast messages. One of the main problem in above-stated standards is the problem of transmission of SpaceWire C-codes. In GigaSpaceWire links these codes are implemented by the pair of symbols - descriptive 8b/10b K-code + C-code itself. In SpaceFibre this code could be implemented by a new 4 byte symbol, which does not go to the Retry level. So at the network level in a routing switch the control-code propagation will be similar to SpaceWire standard but with another time characteristics.