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Unformatted text preview: e number of Transfer Frames which
can be transmitted ahead of the last acknowledged Transfer Frame, i.e., before a CLCW
report is received which updates the status of acknowledged Transfer Frames. This is done
to prevent sending a new Transfer Frame with the same sequence number as a rejected
The value ‘K’ shall be set to a value between the following limits:
1 ≤ K ≤ PW
K < 256
where ‘PW’ is the FARM_Positive_Window_Width as defined in subsection 6.1.8, ‘FARM
Sliding Window Variables’. CCSDS 232.1-B-2 Page 5-9 September 2010 RECOMMENDED STANDARD FOR COMMUNICATIONS OPERATION PROCEDURE-1 5.2 FOP-1 ACTIONS 5.2.1 GENERAL This section defines the actions used in the FOP-1 State Table (table 5-1). Some of the
actions defined here are used in the definition of other actions.
NOTE – It should be noted that the COP-1 Frame Sequence Number is an 8-bit field.
Therefore, all arithmetic in the FOP concerning the related fields V(S), N(R) and
NN(R) should be performed modulo 256. In particular, this should be taken into
account when reading the event conditions contained in the FOP-1 State Tables.
5.2.2 ‘PURGING THE SENT_QUEUE’ This action includes:
clearing the Sent_Queue by generating a ‘Negative Confirm Response to Request to
Transfer FDU’ for each Transfer Frame on the queue and deleting the Transfer
1 Purging the Sent_Queue occurs as part of the termination or (re)initialization (see
Note 2) of an AD Service. 2 Purging is needed when the AD Service is (re)initiated because the FOP may have
reached S6 via a Suspend Indication. 5.2.3 ‘PURGING THE WAIT_QUEUE’ This action includes
clearing the Wait_Queue and generating a ‘Reject Response to Request to Transfer
FDU’ for the queued FDU.
5.2.4 ‘TRANSMIT TYPE-AD FRAME’ This action includes all the functions necessary to prepare a Type-AD Transfer Frame for
transmission. In particular it includes:
a) inserting the current value of V(S) into the N(S) field of the Transfer Frame Primary
Header and then incrementing V(S);
b) adding the master co...
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