Table 2 1 summarizes these services ccsds 1320 b 1

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: r, Master Channel Operational Control Field, and Master Channel Frame) are provided for a Master Channel. Table 2-1 summarizes these services. CCSDS 132.0-B-1 Page 2-6 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL Table 2-1: Summary of Services Provided by TM Space Data Link Protocol Service Service Type Service Data Unit SAP Address Packet Asynchronous Packet GVCID + Packet Version Number Virtual Channel Access (VCA) Asynchronous or Periodic VCA_SDU GVCID Virtual Channel Frame Secondary Header (VC_FSH) Synchronous or Periodic FSH_SDU GVCID Virtual Channel Operational Control Field (VC_OCF) Synchronous or Periodic OCF_SDU GVCID Virtual Channel Frame (VCF) Asynchronous or Periodic Transfer Frame GVCID Master Channel Frame Secondary Header (MC_FSH) Synchronous or Periodic FSH_SDU MCID Master Channel Operational Control Field (MC_OCF) Synchronous or Periodic OCF_SDU MCID Master Channel Frame (MCF) Asynchronous or Periodic Transfer Frame MCID 2.2.3.2 Packet Service The Packet Service transfers a sequence of variable-length, delimited, octet-aligned service data units known as Packets across a space link. The Packets transferred by this service must have a Packet Version Number (PVN) authorized by CCSDS. For the Packet Version Numbers presently authorized by CCSDS, see reference [4]. The service is unidirectional, asynchronous and sequence-preserving. It does not guarantee completeness, nor does it signal gaps in the sequence of service data units delivered to a receiving user. A user of this service is a protocol entity that sends or receives Packets with a single PVN. A user is identified with the PVN and a GVCID. Different users (i.e., Packets with different versions) can share a single Virtual Channel, and if there are multiple users on a Virtual Channel, the service provider multiplexes Packets of different versions to form a single stream of Packets to be transferred on that Virtual Channel. CCSDS 132.0-B-1 Page 2-7 September 2003 CCSDS RECOMMENDATION FOR TM SPACE DATA LINK PROTOCOL 2.2.3.3 Virtual Channel Access (VCA) Service The Virtual Channel Access (VCA) Service provides transfer of a sequence of privately formatted service data units of fixed...
View Full Document

This document was uploaded on 03/06/2014.

Ask a homework question - tutors are online