Section 42 defines the format of the two standard

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Unformatted text preview: ection 4.2 defines the format of the two standard data structures that reside within the layer: the “TC Transfer Frame”, which flows from the sending end of the TC System to its receiving end, and the “Command Link Control Word” (CLCW), which is formatted by the receiving end and is transmitted back to the sending end via corresponding layers within the Telemetry System. Section 4.3 defines the standard procedures which are associated with the layer: – Frame Delimiting and Fill Removal Procedure – Frame Validation Check Procedure – Command Operation Procedure (COP) A COP consists of a pair of synchronized procedures which execute within one TC Virtual Channel (VC) at the sending and receiving ends of the layer. At the sending end a “Frame Operation Procedure” (FOP) is executed. At the receiving end a corresponding spacecraft “Frame Acceptance and Reporting Mechanism” (FARM) is executed. Detail specification of the COPs are contained in Reference [7]. Only one COP is defined in this Recommendation: COP-1. The orientation of these elements within the Transfer layer is shown in Figure 4-1. 4.2 STANDARD DATA STRUCTURES WITHIN THE LAYER This section describes the formats of the following two standard protocol data units which reside within the TC Transfer layer: (1) The TC Transfer Frame, which is the data structure that is “uplinked” to the receiving end of the layer on the spacecraft. (2) The TC Command Link Control Word (CLCW), which is the data structure that is “downlinked” by the spacecraft back to the sending end of the layer in order to provide reports which describe the status of acceptance and reassembly of TC Frames. CCSDS 202.0-B-2 Page 4-1 CCSDS HISTORICAL DOCUMENT November 1992 CCSDS HISTORICAL DOCUMENT CCSDS RECOMMENDATION FOR TELECOMMAND: DATA ROUTING SERVICE (MULTIPLE “VIRTUAL” CHANNELS PROVIDED TO THE LAYER ABOVE) (TC SENDING END) FOP VC 0 FOP VC 1 TC FRAME MULTIPLEXING ••• (TC RECEIVING END) FOP VC n FARM VC 0 CLCW DEMULTIPLEXING FARM VC 1 CLCW MULTIPLEXING ••• FARM VC n TC FRAME DEMULTIPLEXING CLCWs TC FRAMES (TELEMETRY TRANSFER FRAMES) (SINGLE PHYSICAL CHANNEL PROVIDED BY THE LAYER BELOW) Figure 4-1: Orient...
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This document was uploaded on 03/06/2014.

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