4142 the transfer frame data field which shall

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Unformatted text preview: ransfer Frame Primary Header plus the length of the Transfer Frame Secondary Header and/or the Transfer Frame Trailer (if any of these are present). 4.1.4.3 The Transfer Frame Data Field shall contain Packets, one VCA_SDU, or Idle Data. 4.1.4.4 VCA_SDUs shall not be mixed with Packets on the same Virtual Channel. Idle Data shall be transferred on a Virtual Channel that transfers Packets. Whether a particular Virtual Channel transfers Packets (and possibly Idle Data) or VCA_SDUs shall be established by management and static throughout a Mission Phase. CCSDS 132.0-B-1 Page 4-10 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL 4.1.4.5 If Packets are contained in the Transfer Frame Data Field, Packets shall be inserted contiguously and in forward order into the Transfer Frame Data Field. NOTE – The first and last Packets of the Transfer Frame Data Field are not necessarily complete, since the first Packet may be a continuation of a Packet begun in the previous Transfer Frame, and the last Packet may continue in the subsequent Transfer Frame of the same Virtual Channel. 4.1.4.6 In the case where sufficient data (Packets including Idle Packets or a VCA_SDU) are not available to be inserted in a Transfer Frame Data Field at release time for a Transfer Frame, a Transfer Frame with a Data Field containing only Idle Data shall be transmitted. Such a Transfer Frame is called an OID (Only Idle Data in its Data Field) Transfer Frame. The First Header Pointer of an OID Transfer Frame shall be set to ‘11111111110’ (see 4.1.2.7.6) and a project-specified ‘idle’ pattern shall be inserted into the Transfer Frame Data Field. The VCID of an OID Transfer Frame shall be one of the VCIDs used for transferring Packets. NOTES 1 OID Transfer Frames are sent to maintain synchronous transmission of Transfer Frames and also to transmit data in the Transfer Frame Secondary Header and/or the Operational Control Field on a specific Virtual or Master Channel when there is no...
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