Unformatted text preview: e Higher Procedures to generate an
appropriate service indication primitive to deliver a service data unit to the service user.
1 The service indication primitive is issued by the Higher Procedures for a service data
unit, while the ‘FDU Arrived Indication’ signal is issued by FARM-1 for an FDU.
One ‘FDU Arrived Indication’ signal may not result in one service indication
primitive because segmentation or blocking may have been performed by the Higher
Procedures at the sending end (see reference ). 2 In addition to the ‘FDU Arrived Indication’, FARM-1 may optionally send a signal
called ‘Aborted Indication’ to the Higher Procedures when data that were previously
contained in a buffer have been erased in favor of the newly received FDU. This
Recommended Standard does not specify how this signal is delivered. Although an implementation may provide a scheme for flow control between FARM-1 and
the Higher Procedures, this Recommended Standard does not define a specific signal for
flow control. However, if the flow control scheme ever results in the COP-1 Wait_Flag
being set, the scheme must also provide a ‘Buffer Release Signal’. In this case, FARM-1
shall be signaled when sufficient buffer space becomes available for at least one more
3.3.3 FARM-1 INTERFACE TO LOWER PROCEDURES The Lower Procedures shall deliver a received Transfer Frame to FARM-1 by placing it in a
buffer. When a valid Transfer Frame is placed in the buffer, the Lower Procedures shall send
the following signal to FARM-1 to indicate the arrival of the new Transfer Frame (the item
in parentheses is a parameter of the signal):
Valid Frame Arrived Indication (GVCID). CCSDS 232.1-B-2 Page 3-8 September 2010 RECOMMENDED STANDARD FOR COMMUNICATIONS OPERATION PROCEDURE-1 4 DETAILED SERVICE DEFINITION NOTE – This section defines parameters used in some of the service primitives defined in
reference , and complements the service definition of reference . These
parameters are also used in inter-procedure signals defined in section 3 of this
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This document was uploaded on 03/06/2014.
- Spring '14