Oki OKIFAX4550 Maintenance Manual page 279

(6) PC-FAX TX
Figure A.4 (6/13) shows the signal route in PC-FAX TX mode.
The data encoded and HDLC framed in PC is input to IOGA4 via the parallel I/F to be transferred
to the DRAM under the control of DMA.
The stored encoded data is output from DRAM to the MODEM under the control of IOGA4 (CPU).
After modulation, the picture signal "S" is sent to the NCU board as the transmission data. The
transmission data "S" goes through the amplifier and is sent to the telephone line L1 and L2 via
the transformer T1 as high speed signal.
(7) PC-FAX RX
Figure A.4 (7/13) shows the signal route in PC-FAX RX mode.
In the PC-FAX RX mode, the high-speed picture signal arriving from the telephone line at L1 and
L2 of NCU passes through the transformer T1 and the amplifier and is input to the MODEM as
"R" signal. After demodulation by modem, received binary data is sent from the MODEM to
DRAM, under the control of IOGA4 (CPU).
The data written into the DRAM is transferred to the IOGA4 by the DMA to be output to PC via
parallel I/F. The PC deframes and decodes the received data to convert it into image data.
(8) ISDN-G3 TX mode
Figure A.4 (8/13) shows the signal route of this mode.
The signal route from the image sensor to the I-Exseed, DRAM, IOGA4(CPU), and MODEM is
the same as that of the item (2), "G3 send mode". The analog signal "S" encoded and modulated
in the MODEM is sent to the G4N board as the send signal. The analog signal is converted into
the digital signal by the PCM codec on the G4N board to be sent to an ISDN line.
(9) ISDN-G3 RX mode
Figure A.4 (9/13) shows the signal route of this mode.
The high-speed digital image signal received from an ISDN line is converted to analog signal by
the PCM Codec on the G4N board. The converted analog signal is then input to the modem on
the MCNT as "R" signal. The signal route from the modem to the LED head is the same as that
of the item (3) "G3 receive mode".
The signal demodulated by the modem is decoded by the IOGA4 (CPU) and stored into the
DRAM. The signal is then converted into print data by the IOGA4 (printer control) to be
transferred to the LED head as HDATA0.
(10) ISDN PC-FAX G3 TX mode
Figure A.4 (10/13) shows the signal route of this mode.
The signal route from the PC to the modem is the same as that described in item (6) "PC-FAX
TX". The data encoded and HDLC framed in the PC is transferred to the DRAM via the parallel
I/F, IOGA4, and DMA. The signal is then transferred to the modem by the IOGA4(CPU).
The modulated analog signal "S" is sent to the G4N board, where the signal is converted into
digital signal to be output to an ISDN line.
(11) ISDN PC-FAX G3 RX MODE
Figure A.4 (11/13) shows the signal route of this mode.
The high-speed digital image signal received from an ISDN line is converted to analog signal by
the PCM Codec on the G4N board. The converted analog signal is then input to the modem on
the MCNT as "R" signal. The signal route from the modem to PC is the same as that of the item
(7) "PC-FAX RX".
The received binary data demodulated by the modem is sent to the DRAM via the IOGA4(CPU)
and transferred to the IOGA4 by the DMA to be output to the PC via parallel I/F. The PC deframes
and decodes the received data to convert it into image data.
(12) G4 TX mode
Figure A.4 (12/13) shows the signal route of this mode.
The signal route from the image sensor to the I-Exseed, DRAM, IOGA4(CPU), and DRAM is the
same as that of the item (2), "G3 send mode".
The read one-line image data is stored in the DRAM, encoded by the IOGA4(CPU) and again
stored in the DRAM.
In G4 TX mode the encoded data is transferred by the control of IOGA4(CPU) to the dual-port
RAM(DPRAM) on the G4N board. The transferred data is sent to a line via the ISDN controller
and ISDN driver by the control of the CPU on the G4N board.
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