📄 7_3_04.txt
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ciency, implementation which minimizes its effect is desirable.
A.5.4.2 The timer T5 is started at the timing of the first RNR
response recognition.
A.5.4.3 If the timer T5 has expired, the transmitter sends a DCN
command for call release.
A.5.4.4 If RNR response is not received correctly, an RR command
is retransmitted to the receiver. After three unsuccessful
attempts, the transmitter sends a DCN command for call release.
A.5.4.5 After receiving RNR response, the transmitter immediately
sends an RR command until an MCF/PIP response or an ERR/PIN
response is received correctly.
A.5.4.6 An MCF or ERR response indicates that the busy condition
is cleared and the receiver ready to receive the data which follows
the interruption.
Figure A-6/T.30, (N), p.6
A.6 Procedure interrupt
A.6.1 Procedure interrupt signals are not allowed at the par-
tial page boundaries.
A.6.2 Procedure interrupt after detection or transmission of
PIP and PIN signals is accomplished by using the procedure defined
in the main body of this Recommendation. This procedure is outside
the scope of the error correction mode specified in this Annex A.
A.7 Flow Diagrams
The following flow diagrams shows the phase B, pre-message
procedures, phase C, message procedure, phase D, post-message pro-
cedures and phase E, call release, for both the transmitting and
receiving stations.
For the Notes and an explanation of terms to the flow
diagrams, see S A.7.1.
Figure A-7/T.30 (feuillet 1 sur 2), (N), p.7
Figure A-7/T.30 (feuillet 1 sur 2), (N), p.8
Figure A-7/T.30 (feuillet 2 sur 2), (N), p.9
Figure A-7/T.30 (feuillet 2 sur 2), (N), p.10
Figure A-8/T.30, (N), p.11
Figure A-9/T.30, (N), p.12
Figure A-10/T.30, (N), p.13
Figure A-11/T.30, (N), p.14
Figure A-12/T.30, (N), p.15
Figure A-13/T.30, (N), p.16
Figure A-14/T.30, (N), p.17
Figure A-15/T.30, (N), p.18
Figure A-16/T.30, (N), p.19
Figure A-17/T.30, (N), p.20
Figure A-18/T.30, (N), p.21
Figure A-19/T.30, (N), p.22
Figure A-20/T.30, (N), p.23
Figure A-21/T.30, (N), p.24
Figure A-22/T.30, (MC), p.25
Figure A-23/T.30, (MC), p.26
Figure A-24/T.30, (N), p.27
Figure A-25/T.30, (N), p.28
A.7.1 Flow diagram key
COMMAND REC The "command received" subroutine searches for an
error-free standard command. The decision diamonds in the flow
diagram refer to the most recent standard command received
(e.g., EOM, MPS, etc.). COMPT REMOTE REC The FIF associated with
the DIS has indicated a "compatible remote receiver". DOC TO XMIT
The station has "at least one document to be transmitted".
COMPT REMOTE XMTR The FIF associated with the DIS has indicated a
"compatible remote transmitter" which has documents to send.
RESPONSE REC The "response received" subroutine which searches for
an error-free standard response. LAST DOC The "last document", for
the given operating mode, has been transmitted. SET MODE The sys-
tem controller will "set the appropriate mode" of operation.
3RD TRY The command has been repeated three times without an
appropriate response. CAPABLE RE-XMIT The transmitting station is
"capable of retransmitting" a document which was not received with
acceptable quality. MSG CARRIER REC The "message channel carrier
has been received". This carrier is 1800 Hz for the Group 3 modula-
tion scheme, and 1700 Hz for the Group 3 optional modulation
scheme, 2100 Hz for the Group 2 modulations, and 1300-2100 Hz for
the Group 1 modulation scheme.
PHASE/TRAIN OK The phasing/training-TCF signal has been analyzed
and the results of "phasing/training were OK". CHANGE MODE The
transmitting unit desires to exit from the transmitting mode of
operation and reestablish the capabilities. NSP REQ A
"non-specified procedure" has been "recognized" by a unit compati-
ble with the station initiating that procedure. COPY QUALITY OK By
some algorithm, the "copy quality was deemed OK".
REPHASE/TRAIN By some algorithm, it is deemed desirable to transmit
a new phasing/training signal. FLAG There has been the detection
of a "flag". RECEIVE A FRAME The unit has "received one complete
HDLC frame". FCS ERROR The HDLC frame received contained an "FCS
error".
OPTIONAL RESPNS The HDLC frame received contained one of the listed
"optional responses". OPTIONAL COMMAND The HDLC frame received
contained one of the listed "optional commands". CRP OPTION The
facsimile unit has the "CRP option" and can, therefore, request an
immediate retransmission of the most recent command.
LOCAL INT Either the "local" machine or the "local" operator wishes
to generate an interrupt of the standard facsimile procedures. An
operator would use this as a means to request the establishment of
voice contact. LINE REQ This means that the local operator has
"requested" that the telephone line be connected to the handset for
voice contact with the remote end. PRI-Q A general term referring
to either PRI-EOM, a PRI-MPS, or a PRI-EOP post-message command,
i.e., the fifth bit of the standard post-message command is set
to 1. END OF PAGE? The transmitting station may have further data
to transmit to complete the page.
4TH PPR? PPR has been received 4 times. TRANSMIT ERROR FRAMES The
frames defined in the information field associated with PPR are
transmitted using the V.27 | fIter /V.29 modulation system.
CONTINUE TO CORRECT? The transmitting station by some algorithm
decides to continue correcting the previous message.
CONT WITH NEXT MSG? The transmitting station by some algorithm
decides to continue and transmit the next message. The previous
message was not satisfactorily transmitted.
PPSxPRI-Q? The terminal has "received either PPSxPRI-EOM,
PPSxPRI-MPS, or PPSxPRI-EOP post-message command". PPSxQ? The
terminal has "received either PPSxEOM, PPSxMPS, PPSxEOP or PPSxNull
post-message command." EORxPRI-Q? The terminal has "received
either EORxPRI-EOM, EORxPRI-MPS, or EORxPRI-EOP post-message com-
mand." EORxQ? The terminal has "received either EORxEOM, EORxMPS,
EORxEOP or EORxNull post-message command".
RECEIVE READY? The receiving station is ready to receive the next
message. RR RESPONSE REC? The "RR response received" subroutine
searches for an error-free response for the RR command.
CTC RESPONSE REC? The "CTC response received" subroutine searches
for an error-free response for the CTC command.
Note 1 - The non-specified procedure, NSP, refers to a pro-
cedure which takes 6 seconds or less to complete. It may not neces-
sarily be a definable signal sequence.
Note 2 - This signal pertains to Group 3 apparatus only.
Note 3 - The PRI-EOM, PRI-EOP, PRI-MPS post-message commands
are sent when a local interrupt request is pending.
Note 4 - At any time during the operation an interrupt may be
generated which would result in a procedural interrupt. It is
understood that if this interrupt happens during the transmission
of the document, the EOM/RTC signal will be transmitted prior to
invoking the procedural interrupt.
Note 5 - Where the symbol / is used, the term to the left of
the symbol refers to Groups 1 and 2 equipment, and the term to the
right of the symbol refers to Group 3 equipment.
Note 6 - Where the symbols { } are used, the signals within
these symbols are a response to DIS from the calling unit wishing
to receive.
Note 7 - Where the symbols ( ) are used, the signals within
these symbols are optional.
A.8 Signal sequence examples in case of error correction
procedure
The examples below are based on the flow diagrams and for
illustrative and instructional purposes only. They should not be
interpreted as establishing or limiting the protocol. The exchange
of the various commands and responses is limited only by the rules
specified in this Recommendation.
In these diagrams the dashed lines indicate transmission at
the message data rate (Recommendation V.27 | fIter , V.29), and (X,
Y) means (page modulo number, block modulo number).
Blanc
Figure A-26/T.30 (feuillet 1 sur 13), (N), p.
Figure A-26/T.30 (feuillet 2 sur 13), (N), p.30
Figure A-26/T.30 (feuillet 3 sur 13), (N), p.31
Figure A-26/T.30 (feuillet 4 sur 13), (N), p.32
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