Unformatted text preview: ovided by the
Transfer layer. Multiplexing allows user data structures with different delivery priorities to
share the same Virtual Channel and thus provides flow control.
NEXT EXPECTED FRAME SEQUENCE NUMBER N(R):
The observed current value of V(R) that is telemetered from the FARM to the FOP via each
CLCW. CCSDS 202.0-B-2 Page A-4 CCSDS HISTORICAL DOCUMENT November 1992 CCSDS HISTORICAL DOCUMENT
CCSDS RECOMMENDATION FOR TELECOMMAND: DATA ROUTING SERVICE PACKETIZATION LAYER:
The bottom layer of the Data Management Service, specified in Reference . This is the
layer immediately above the Segmentation layer.
The value of the Frame Sequence Number, N(S), which the FARM expects to see in the next
Type-A frame in order to preserve up-counting sequence.
A flag indication from the FARM, contained in a CLCW, that at least one Type-A frame has
been rejected and that retransmission is required from the FOP.
The top layer of the Data Routing Service, which interfaces user data structures with the
protocols used during transfer to the receiving spacecraft.
TELECOMMAND FRAME DATA UNIT (TC FRAME DATA UNIT)
The data unit generated by the Segmentation layer to be placed in the data field of the TC
Transfer Frame which will convey the data to the spacecraft. It will consist of a TC Segment,
one or more complete TC Packets or a single TC User Data Unit.
TELECOMMAND SEGMENT (TC SEGMENT):
The protocol data unit of the TC Segmentation layer. A TC Segment consists of a Segment
Header and Segment Data Field.
TELECOMMAND TRANSFER FRAME (TC TRANSFER FRAME or TC FRAME):
The protocol data unit of the Transfer layer. TC Transfer Frames contain a Frame Header, a
Frame Data Field, and an optional Frame Error Control Field. The Data Field carries either a
TC Frame Data Unit (e.g., a TC Segment or TC Packet(s)) or a Control Command, which
establishes the internal operations of the Transfer layer.
TELECOMMAND USER DATA UNIT (TC USER DATA UNIT):
A finite-length user data structure provided by the layers ab...
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This document was uploaded on 03/06/2014.
- Spring '14