42114101 Rev.1
129 /
OCS
P1
P2
P0
P3
TD
RD
IF WR
LS245
ROM
64Kbit
RD
TD
RAM
64Kbit
Driver
+5 VD
+12VDC
-8VDC
+5 V
+9 V
–
9 V
+5V
0V
±
9 V power
supply circuit
Serial data
control line
Bus line
Control line
ADR latch
Receiver
DB0 to DB9
ADR/data bus
ADR bus
80C51
RST
CN1
75188
75189
Figure C-1 Block Diagram
2.2
Circuit Description
A block diagram is shown in Figure C-1.
2.2.1 Operation at power on
After power is turned on, an RST OUT signal is sent from the printer control board to reset the
printer. When the reset is canceled, the 80C51 CPU performs initialization. Initialization consists
of setting the 80C51 timer, and setting the serial mode.
2.2.2. RS-232C interface
The DTR, SSD, TD and RTS signals output by the 80C51 are converted to RS-232C signals
by line driver 75188 (Q1) and sent to the interface.
In addition, signals DSR, CTS, CD, and RD on the RS232C interface are converted to TTL level
by line receiver 75189 (Q2) and input to the 80C51.
Содержание ML490 Series
Страница 1: ...42114101 Rev 1 1 135 ML490 491 PRINTER Maintenance Manual ODA...
Страница 2: ...42114101 Rev 1 2...
Страница 38: ...42114101 Rev 1 38 Drive gear Ink tank Ribbon cartridge Figure 2 6...
Страница 48: ...42114101 Rev 1 48 Change arm Change lever Platen Release cam Figure 2 13 REAR TOP BOTTOM...
Страница 96: ...42114101 Rev 1 96 9 Carriage Assy NK2 10 SUS Bearing portion of guide roller EM 30L B...
Страница 119: ...42114101 Rev 1 119 6 8 9 7 1 2 3 11 10 4 5 Figure B 2 Printer General Assy...
Страница 124: ...42114101 Rev 1 124 9 12 11 1 13 3 7 1 14 5 6 7 2 10 8 Figure B 4 Carriage Assy...
Страница 126: ...42114101 Rev 1 126 Figure B 5 Option Spare Parts Pull Tractor Bottom Tractor I F Board 3 2 1 4 5 6 7...
