Indication primitive shall be passed from the service

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Unformatted text preview: mitive shall be used to deliver Transfer Frames of a Master Channel to the VCF Service user identified by the MCID. CCSDS 132.0-B-1 Page 3-26 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL 4 4.1 PROTOCOL SPECIFICATION PROTOCOL DATA UNIT 4.1.1 TM TRANSFER FRAME A TM Transfer Frame shall encompass the major fields, positioned contiguously, in the following sequence: a) Transfer Frame Primary Header (6 octets, mandatory); b) Transfer Frame Secondary Header (up to 64 octets, optional); c) Transfer Frame Data Field (integral number of octets, mandatory); d) Operational Control Field (4 octets, optional); e) Frame Error Control Field (2 octets, optional). The TM Transfer Frame shall be of constant length throughout a specific Mission Phase for any Virtual Channel or Master Channel on a Physical Channel. Its length shall be consistent with the specifications contained in reference [3]. The structural components of the TM Transfer Frame are shown in figure 4-1. NOTES 1 The protocol data unit of the TM Space Data Link Protocol is the TM Transfer Frame. In this Recommendation, the TM Transfer Frame is also called the Transfer Frame, or Frame, for simplicity. 2 The combination of the Operational Control Field and the Frame Error Control Field is called the Transfer Frame Trailer. 3 The start of the Transfer Frame is signaled by the underlying Channel Coding Sublayer. 4 A change of Transfer Frame Length may result in a loss of synchronization at the receiver. CCSDS 132.0-B-1 Page 4-1 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL TM TRANSFER FRAME TRANSFER FRAME TRAILER (Optional) TRANSFER FRAME PRIMARY HEADER TRANSFER FRAME SECONDARY HEADER (Optional) TRANSFER FRAME DATA FIELD 6 octets Up to 64 octets Varies OPERATIONAL CONTROL FIELD (Optional) FRAME ERROR CONTROL FIELD (Optional) 4 octets 2 octets Figure 4-1: TM Transfer Frame Structural Components 4.1.2 TRANSFER FRAME PRIMARY HEADER General The Transfer Frame Primary Header is mandatory and shall consist of six fields, positioned contiguously, in the following sequence: a) Master Channel Identifier (12 bits, mandatory); b) Virtual Channel Identifier (3 bits, mandatory); c) Operational Control Field Flag (1 bit, manda...
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This document was uploaded on 03/06/2014.

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