Therefore the newcomer may find it helpful to

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Unformatted text preview: -1 Revision B (or simply FOP-1B) that is introduced in Issue 2 of the Command Operation Procedures-1 (reference [B2]). The original FOP-1 (or FOP-1 Revision A) is defined in Issue 1 of the Command Operation Procedures-1 (reference [B3]). 2 A brief explanation on the format of the State Table is given in annex C. 5.3.2 NOTES TO FOP-1 STATE TABLE CLCW Arrival In the case of the arrival of a CLCW, some operations must be performed by FOP-1 before the FOP-1 State Table is applied. In particular, not included in the FOP-1 State Table are operations such as checking: CCSDS 232.1-B-2 Page 5-14 September 2010 RECOMMENDED STANDARD FOR COMMUNICATIONS OPERATION PROCEDURE-1 a) the ‘COP in Effect’; b) the ‘Virtual Channel Identifier’. Included in the FOP-1 State Table are the following operations: a) checking the value of the ‘Lockout’ Flag; b) checking the value of N(R); c) checking the value of the ‘Retransmit’ Flag; d) checking the value of the ‘Wait’ Flag. CLCW Values In the FOP-1 State Table, references to the following values pertain to the values in the current CLCW: a) Lockout Flag; b) Wait Flag; c) Retransmit Flag; d) N(R). 5.3.3 FOP-1 STATE TRANSITIONS The FOP-1 State Table is large and the state transitions complex. Therefore, the newcomer may find it helpful to consider initially only the state changes relating to the main protocol. This is shown, for the normal situation in which no exception conditions occur, in figure 5-1. This protocol is capable of automatically handling flow control and error control (providing the quality of the link is not so low that a maximum of Transmission_Limit transmissions fail to transfer a Transfer Frame to the receiving end). It is not capable of handling improper operation of the communications link, which can be caused, for example, by two sending ends simultaneously sending Transfer Frames to the same receiving end. Next, consideration should be given to the initialization protocol, which is used to initiate and terminate a session using the AD Service. This is shown in figure 5-2, which shows the main protocol States (S1), (S2) and (S3) coalesced into a single state. The FOP-1 State T...
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