This preview shows page 1. Sign up to view the full content.
Unformatted text preview: ithin
The FRAME SEQUENCE NUMBER enables the FARM to check the
sequentiality of incoming Type-A TC Frames. The 8-bit FRAME SEQUENCE
NUMBER field supports a modulo-256 sequence count.
The FRAME SEQUENCE NUMBER is Virtual Channel dependent; i.e., the
Transfer layer shall maintain a separate FRAME SEQUENCE NUMBER for each
of the (up to 64) VIRTUAL CHANNELS. Note that the COP does not use this field when operating with Type-B TC Frames; in this
case the contents of the FRAME SEQUENCE NUMBER field shall be set to “all zeros”.
Transfer Frame Data Field. The FRAME DATA FIELD, which is of
variable length up to a maximum of 1019 octets (1017 octets if the FRAME ERROR
CONTROL FIELD is present), shall contain either an integral number of octets of
telecommand data corresponding to one TC Frame Data Unit or an integral number of octets
of Control Command information. The FRAME DATA FIELD shall be inserted directly
after the Frame Header with no filler between.
220.127.116.11.1 TC Frame Data Unit. The TC Frame Data Unit is supplied by the Segmentation
layer. The content of a TC Frame Data Unit is defined in Section 3.3.1.
18.104.22.168.2 Control Commands. There are two Control Commands defined: UNLOCK and
SET V(R). The action to be taken when the FARM receives one of the Control Commands is
defined in Reference . All other bit combinations for Control Commands are reserved by
the CCSDS for future application.
UNLOCK: The UNLOCK Control Command consists of a single octet containing
SET V(R): The SET V(R) Control Command consists of three octets with the
10000010 00000000 XXXXXXXX
where XXXXXXXX is the value to which the FARM should set V(R), the
Receiver_Frame_Sequence_Number. This octet should therefore be set to the
Sequence Number which will be put into the Header of the next Type-A TC Frame to
be transmitted on that Virtual Channel. CCSDS 202.0-B-2 Page 4-7 CCSDS HISTORICAL DOCUMENT November 1992 CCSDS HISTORICAL DOCUMENT
CCSDS RECOMMENDATION FOR TELECOMMAND: DATA ROUTING SERVICE 22.214.171.124
Transfer Frame Error Control Field. The purpose of this opt...
View Full Document
This document was uploaded on 03/06/2014.
- Spring '14