When bit 19 is set to value 0 ie dont wait normal

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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 [7]. 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 [7]. 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 Reference [7]. 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 [7]. 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 CCSDS 202.0-B-2 Page 4-13 CCSDS HISTORICAL DOCUMENT November 1992 CCSDS HISTORICAL DOCUMENT CCSDS RECOMMENDATION FOR TELECOMMAND: DATA ROUTING SERVICE (9) RESERVED SPARE (Bit 23) This bit is reserved by CCSDS for future application.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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This document was uploaded on 03/06/2014.

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