Unformatted text preview: TM SPACE DATA LINK PROTOCOL 18.104.22.168 If there is a user of the VC_FSH Service for a particular Virtual Channel, an
FSH_SDU supplied by the user shall be placed in the Transfer Frame Secondary Header. If
there is a user of the VC_OCF Service for a particular Virtual Channel, an OCF_SDU
supplied by the user shall be placed in the Operational Control Field.
The Master Channel Frame Count field of Transfer Frames shall be kept empty by the
Virtual Channel Generation Function. The following fields of Transfer Frames, if present for
the particular Physical or Master Channel, shall also be kept empty by the Virtual Channel
b) MC_OCF; and
c) Frame Error Control Field.
22.214.171.124 An abstract model of the Virtual Channel Generation Function is illustrated in
Only one of these two entities
exists for a Virtual Channel Packet Proc.
Data Fields Virtual
Service User VCA_SDUs VC_FSH
Service User VC_OCF
Service User FSH_SDUs OCF_SDUs Transfer Frame Generation VC Frames
Virtual Channel Multiplexing Function Figure 4-7: Abstract Model of Virtual Channel Generation Function
4.2.4 VIRTUAL CHANNEL MULTIPLEXING FUNCTION 126.96.36.199 The Virtual Channel Multiplexing Function shall be used to multiplex Transfer
Frames of different Virtual Channels of a Master Channel.
NOTE – There is an instance of the Virtual Channel Multiplexing Function for each
Master Channel that has multiple Virtual Channels.
188.8.131.52 The Virtual Channel Multiplexing Function shall multiplex Transfer Frames
received from the instances of the Virtual Channel Generation Function and, if present, the CCSDS 132.0-B-1 Page 4-17 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL Virtual Channel Frame Service users, and shall put them into a queue of Transfer Frames in
an appropriate order that is set by management.
184.108.40.206 The algorithm used to order the Transfer Frames is not specified by CCSDS, but
shall be defined by project organizations, considering factors such as priority, release rate,
isochronous timing requirements, etc...
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- Spring '14
- Space Exploration, European Space Agency, Protocol data unit