Unformatted text preview: by the FARM
until the condition is cleared by freeing the congestion, either automatically or
by taking appropriate control action as defined in Reference .
When Bit 19 is set to value “0” (i.e., DON’T WAIT), normal Type-A
commanding may proceed on that channel.
The precise specifications for use of the WAIT Flag are contained in
Reference . Necessarily, separate WAIT flags shall be maintained for each
Virtual Channel. (e) RETRANSMIT Flag (Bit 20)
The RETRANSMIT flag speeds the operation of the COP by providing
immediate indication (Bit 20 set to value “1”) to the FOP at the sending end
that one or more Type-A frames on a particular TC Virtual Channel have been
rejected or found missing by the FARM and therefore retransmission is
required. The conditions which cause the flag to be set are specified in
When Bit 20 is set to value “0”, this indicates that there are no outstanding
Type-A frame rejections in the sequence received so far, and thus
retransmissions are not required.
The precise specifications for use of the RETRANSMIT Flag are contained in
Reference . Necessarily, separate RETRANSMIT flags shall be maintained
for each Virtual Channel. (8) FARM-B COUNTER (Bits 21,22)
This field contains the two least significant bits of a FARM-B COUNTER. This
counter is maintained within the FARM and increments once each time a Type-B
TC Transfer Frame is accepted in BYPASS mode on a particular Virtual Channel.
The field supports the verification that BYPASS mode frames (Control or user
Data) were accepted by the spacecraft.
Necessarily, separate FARM-B COUNTERs shall be maintained for each Virtual
Channel. CCSDS 202.0-B-2 Page 4-13 CCSDS HISTORICAL DOCUMENT November 1992 CCSDS HISTORICAL DOCUMENT
CCSDS RECOMMENDATION FOR TELECOMMAND: DATA ROUTING SERVICE (9) RESERVED SPARE (Bit 23)
This bit is reserved by CCSDS for future application. For the present, Bit 23 shall
be set to value “0”. (10) REPORT VALUE (Bits 24-31)
This field, which shall always be one octet long, contains the value of “N(R)”, i.e.,
the current obser...
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