Unformatted text preview: Frames, and deliver the Transfer Frames to the entities of FARM-1 (there is an
entity of FARM-1 for each Virtual Channel). FARM-1 shall examine incoming Transfer
Frames, perform Frame Acceptance Checks against Type-A Transfer Frames, execute
Control Commands, generate some information to be transferred back to FOP-1 in CLCWs,
and deliver FDUs extracted from Transfer Frames to the Higher Procedures. The Higher
Procedures shall reconstruct service data units from FDUs and deliver the service data units
to users of the protocol.
The users of the TC Space Data Link Protocol shall receive service data units from the
protocol entity through SAPs using service primitives defined in reference .
3.3.2 FARM-1 INTERFACE TO HIGHER PROCEDURES FARM-1 shall interact with the Higher Procedures using inter-procedure signals. These
inter-procedure signals are related to service primitives exchanged between users of the
protocol and the protocol entity, and it is assumed in this Recommended Standard that the
Higher Procedures shall perform the necessary conversion between service primitives
defined in reference  and inter-procedure signals defined here.
When a Type-AD Transfer Frame is accepted by FARM-1, the FDU contained in the
Transfer Frame shall be placed in a buffer for delivery to the Higher Procedures only when CCSDS 232.1-B-2 Page 3-7 September 2010 RECOMMENDED STANDARD FOR COMMUNICATIONS OPERATION PROCEDURE-1 there is a buffer available. If there is no buffer available, the newly arrived Type-AD
Transfer Frame shall be discarded.
When a Type-BD Transfer Frame is accepted by FARM-1, the FDU contained in the
Transfer Frame shall be placed in a buffer for delivery to the Higher Procedures even if there
is no buffer available, in which case the data in the buffer will be erased and an optional
‘Aborted Indication’ signal may be sent to the Higher Procedures.
When a new FDU is accepted, FARM-1 shall send the following signal to the Higher
Procedures to indicate the arrival of the new FDU:
FDU Arrived Indication (GVCID).
The ‘FDU Arrived Indication’ signal is processed by th...
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