Black Box IC113C User manual

CUSTOMER
SUPPORT
INFORMATION
Order toll-free in the U.S. 24 hours, 7 A.M. Monday to midnight Friday: 877-877-BBOX
FREE technical support, 24 hours a day, 7 days a week: Call 724-746-5500 or fax [phone]
Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [email protected]
MARCH 2000
IC113C
IC175C
Dual Port RS-232/422/485 Serial Interface

FCC AND IC STATEMENTS, TRADEMARKS
FEDERAL COMMUNICATIONS COMMISSION
AND
INDUSTRY CANADA
RADIO FREQUENCY INTERFERENCE STATEMENTS
This equipment generates, uses, and can radiate radio frequency energy
and if not installed and used properly, that is, in strict accordance with the
manufacturer’s instructions, may cause interference to radio communication.
It has been tested and found to comply with the limits for a Class A
computing device in accordance with the specifications in Subpart J of
Part 15 of FCC rules, which are designed to provide reasonable protection
against such interference when the equipment is operated in a commercial
environment. Operation of this equipment in a residential area is likely to
cause interference, in which case the user at his own expense will be required
to take whatever measures may be necessary to correct the interference.
Changes or modifications not expressly approved by the party responsible
for compliance could void the user’s authority to operate the equipment.
This digital apparatus does not exceed the Class A limits for radio noise emission from
digital apparatus set out in the Radio Interference Regulation of Industry Canada.
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites
applicables aux appareils numériques de la classe A prescrites dans le Règlement sur le
brouillage radioélectrique publié par Industrie Canada.
TRADEMARKS USED IN THIS MANUAL
AT and IBM are registered trademarks, and XT is a trademark of
International Business Machines Corporation.
Any other trademarks mentioned in this manual are acknowledged to be the property
of the trademark owners.

DUAL PORT RS-232↔422/485 SERIAL INTERFACE
NORMAS OFICIALES MEXICANAS (NOM)
ELECTRICAL SAFETY STATEMENT
INSTRUCCIONES DE SEGURIDAD
1. Todas las instrucciones de seguridad y operación deberán ser leídas antes
de que el aparato eléctrico sea operado.
2. Las instrucciones de seguridad y operación deberán ser guardadas para
referencia futura.
3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de
operación deben ser respetadas.
4. Todas las instrucciones de operación y uso deben ser seguidas.
5. El aparato eléctrico no deberá ser usado cerca del agua—por ejemplo,
cerca de la tina de baño, lavabo, sótano mojado o cerca de una alberca,
etc..
6. El aparato eléctrico debe ser usado únicamente con carritos o pedestales
que sean recomendados por el fabricante.
7. El parato eléctrico debe ser montado a la pared o al techo sólo como sea
recomendado por el fabricante.
8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico más
allá a lo descrito en las instrucciones de operación. Todo otro servicio
deberá ser referido a personal de servicio calificado.
9. El aparato eléctrico debe ser situado de tal manera que su posición no
interfiera su uso. La colocación del aparato eléctrico sobre una cama,
sofá, alfombra o superficie similar puede bloquea la ventilación, no se
debe colocar en libreros o gabinetes que impidan el flujo de aire por los
orificios de ventilación.
10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de
calor como radiadores, registros de calor, estufas u otros aparatos
(incluyendo amplificadores) que producen calor.

NOM STATEMENT
11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo
del tipo descrito en el instructivo de operación, o como se indique en el
aparato.
12. Precaución debe ser tomada de tal manera que la tierra fisica y la
polarización del equipo no sea eliminada.
13. Los cables de la fuente de poder deben ser guiados de tal manera que no
sean pisados ni pellizcados por objetos colocados sobre o contra ellos,
poniendo particular atención a los contactos y receptáculos donde salen
del aparato.
14. El equio eléctrico debe ser limpiado únicamente de acuerdo a las
recomendaciones del fabricante.
15. En caso de existir, una antena externa deberá ser localizada lejos de las
lineas de energia.
16. El cable de corriente deberá ser desconectado del cuando el equipo no
sea usado por un largo periodo de tiempo.
17. Cuidado debe ser tomado de tal manera que objectos liquidos no sean
derramados sobre la cubierta u orificios de ventilación.
18. Servicio por personal calificado deberá ser provisto cuando:
A: El cable de poder o el contacto ha sido dañado; u
B: Objectos han caído o líquido ha sido derramado dentro del
aparato; o
C: El aparato ha sido expuesto a la lluvia; o
D: El aparato parece no operar normalmente o muestra un cambio en su
desempeño; o
E: El aparato ha sido tirado o su cubierta ha sido dañada.

DUAL PORT RS-232↔422/485 SERIAL INTERFACE
Contents
Chapter Page
1. Specifications...................................................................................................1
2. Introduction ....................................................................................................2
2.1 Overview..................................................................................................2
2.2 What’s Included......................................................................................2
2.3 Features ...................................................................................................3
2.4 Technical Description ............................................................................4
3. Address Selection............................................................................................6
4. Option Selection .............................................................................................7
4.1 Port Enable/Disable...............................................................................7
4.2 RS-232 Interface Options .......................................................................9
4.3 RS-422/485 Interface Options.............................................................10
4.4 Line Termination .................................................................................11
5. Installation.....................................................................................................12
Appendix: Circuit-Board Design.......................................................................14

1
CHAPTER 1: Specifications
Protocol — Asynchronous
Speed — IC113C: Up to 115.2 Kbps; IC175C: 460.8 kbps and higher
Operation — RS-232 or RS-485/422, 2- or 4-wire (individually selectable
on each port)
Connectors — (2) DB9M
Communications Chip — IC113C: 16550 UART; IC175C: 16950 UART
MTBF — >150,000 hours
MTTR — <0.25 hours
Materials — Boards are solder mask over bare copper or tin nickel
Operating Temperature — 32° to 122°F (0° to 50°C)
Storage Temperature — -4° to 158°F (-20° to 70°C)
Humidity — 0 to 90% relative humidity, noncondensing
Power — +5 VDC @ 195 mA ±12 V @ 25 mA (derived from PC bus)
Size — 5"W x 7.5 "D (12.7 x 19 cm)
Weight — 0.2 lb. (0.1 kg)
1. Specifications

2
DUAL PORT RS-232↔422/485 SERIAL INTERFACE
2.1 Overview
If you need to operate RS-232, RS-422, or RS-485 devices from your PC, use
the Dual Port RS-232/422/485 Serial Interface. Connect to any device that
uses the RS-232 interface, such as modems, data-entry terminals, and plotters.
This card allows you to configure two RS-232 ports, two RS-422/485 ports, or
one of each. The Dual Port RS-232/422/485 also features greater maximum
distance and allows multi-drop communications.
The card also includes a serial utility disk with Seacom, a DOS interrupt and
driver package. Seacom allows data to be buffered, eliminating data loss in
high-speed data transfers. It also allows more than 4 ports (256 max.) to be
configured and utilized under DOS.
The README file on the serial utility disk contains information about the
latest changes and revisions. To view this file, insert the diskette into drive A
or B and type A:TYPE READ.ME|MORE [ENTER] or B:TYPE
READ.ME|MORE [ENTER].
2.2 What’s Included
Your Serial Interface should come with the following items. If any of these
items are missing or damaged, contact Black Box at 724-746-5500.
(1) Dual Port RS-232/422/485 Serial Interface card,
(2) serial utility software diskettes: (1) for 32-bit Windows®,
(1) for DOS and Windows®3.1x,
This manual
2. Introduction

3
CHAPTER 2: Introduction
2.3 Features
Listed below are the special features your Serial Interface offers.
• Each port is independently addressable.
• Eleven interrupt options, including AT interrupts, for simple integration
into existing systems.
• IRQs (2 [9], 3, 4, 5, 6, 7, 10, 11, 12, and 15) supported.
• IRQs can be shared or individually set for each port.
• Supports Interrupt Sharing—only one interrupt line required for
multiple ports.
• Supports any character set defined by binary notation.
• 16550 UARTs on the IC113C help ensure against data loss. This chip
features programmable baud rate, data format, interrupt control, and a
16-byte FIFO. The IC175C uses 16950 UARTs, which feature a 128-byte
buffer for even better performance.
• Faster baud rates—up to 115.2 Kbps (IC113C) or 460.8 kbps and above
(IC175C).
• Addressable as COM1: through COM4: or any other address up
to 3FF Hex.
• Support for non-standard baud rates available. These baud rates (such as
31.25K or 76.8K baud) are supported by installing a different oscillator at
location Y1. Call Technical Support for more information.

4
DUAL PORT RS-232↔422/485 SERIAL INTERFACE
2.4 Technical Description
The Dual Port RS-232/422/485 Serial Interface utilizes the same 16550 UART
chip found in the IBM®asynchronous adapter. This chip features
programmable baud rate, data format, and interrupt control. Refer to the
IBM Technical Reference for details on programming the chip.
RS-232
The Dual Port RS-232/422/485 Serial Interface meets the RS-232C
specifications and provides an asynchronous serial I/O port. This is the
standard port configuration found in the IBM AT®computer, including the
DB9 style connector.
The table below shows the connector pinouts for ports J1 (port 1) and J2
(port 2) on the Interface while using RS-232.
Pin Number Signal Name Mode
3 Transmit Data (TD) Output RS-232
7 Request To Send (RTS) Output RS-232
4 Data Term Ready (DTR) Output RS-232
5 Ground (GND) ––––––––––––
2 Receive Data (RD) Input RS-232
1 Data Carrier Detect (DCD) Input RS-232
6 Data Set Ready (DSR) Input RS-232
8 Clear To Send (CTS) Input RS-232
9 Ring Indicator (RI) Input RS-232
RS-422
RS-422 allows very long distance communications—4000 feet (about
1219 meters) at 9600 baud—based on use of Category 3, UTP, or better, with
virtually error-free differential drive characteristics. RS-422 signal levels are
the standard electrical specification used in RS-449 and EIA-530. This allows
interfacing with equipment that meets these specifications.

5
CHAPTER 2: Introduction
RS-485
RS-485 is backward-compatible with RS-422; however, it is optimized for
multidrop applications. The output of the RS-422/485 driver is capable of
being active (enabled) or tri-state (disabled). This capability allows multiple
ports to be connected in a multidrop bus and selectively polled. Half-duplex
two-wire communications are possible by connecting TX+ to RX+ and TX- to
RX- in your cable connector. The enable to the driver is connected to the
UART Request To Send (RTS) line for RS-485 communications. This allows
the RS-485 driver to be tri-stated (disabled) when inactive on a multidrop
polled network. The software that you are using must “know how” to enable
the driver when it is answering a poll. Failure to set this jumper correctly can
cause transmitter contention problems, preventing operation by any nodes on
the network.
The table below shows the connector pinouts for ports J1 (port 1) and J2
(port 2) on the Interface while using RS-422/485.
Pin Number Signal Name Mode
4 Transmit Data Pos. (TX+) Output RS-422
3 Transmit Data Neg. (TX-) Output RS-422
6 Req. To Send Pos. (RTS+) Output RS-422
7 Req. To Send Neg. (RTS-) Output RS-422
5 Ground (GND) --------------------
1 Receive Data Pos. (RX+) Input RS-422
2 Receive Data Neg. (RX-) Input RS-422
9 Clear To Send Pos. (CTS+) Input RS-422
8 Clear To Send Neg. (CTS-) Input RS-422

6
DUAL PORT RS-232↔422/485 SERIAL INTERFACE
NOTE
Be sure to set the address selections and jumper options before
installation.
Each serial port on the Dual Port RS-232/422/485 Serial Interface occupies
8 consecutive I/O locations. DIP switch SW1 sets the base address for Port 1,
and DIP switch SW2 sets the address for Port 2. Be careful when selecting the
base address, since some selections conflict with existing PC ports. The
following table shows several examples that usually do not cause a conflict.
Address Binary Switch Position Setting
Hex A9 A0 1 2 3 4 5 6 7
280-287 1010000XXX OFF ON OFF ON ON ON ON
2A0-2A7 1010100XXX OFF ON OFF ON OFF ON ON
2E8-2EF 1011101XXX OFF ON OFF OFF OFF ON OFF
2F8-2FF 1011111XXX OFF ON OFF OFF OFF OFF OFF
3E8-3EF 1111101XXX OFF OFF OFF OFF OFF ON OFF
300-307 1100000XXX OFF OFF ON ON ON ON ON
328-32F 1100101XXX OFF OFF ON ON OFF ON OFF
3F8-3FF 1111111XXX OFF OFF OFF OFF OFF OFF OFF
Typically COM1:=3F8h; COM2:=2F8h; COM3:=3E8h; COM4:=2E8h
The following illustration shows the correlation between the DIP switch
setting and the address bits used to determine the base address. In the figure
below, the address 300 hex through 307 hex is selected (300 hex =11 0000
0XXX in binary representation). Note that setting the switch ON (or closed)
corresponds to a “0” in the address, while leaving it OFF (or open)
corresponds to a “1.”
A9 A3
ON
OFF
EN
0
1
1 2 3 4 5 6 7 8
3. Address Selection

7
CHAPTER 4: Option Selection
NOTE
Be sure to set the address selections and jumper options before
installation.
The board contains several jumper straps for each port which must be set for
proper operation.
4.1 Port Enable/Disable
Each port on the Dual Port RS-232/422/485 can be enabled or disabled with
switch position 8 on the DIP switch. The port is enabled with the switch ON
(or closed) and disabled when OFF (or open). If any port is disabled, be sure
to also disable the interrupt request for that port by removing the IRQ jumper
(see Figure 4-1).
I
NTERFACE S ELECTION
RS-422/485
To select the RS-422/485 mode of operation, install DIP shunts in sockets
found at E6 and E7. E6 sets Port 1 and E7 sets Port 2.
RS-232
To select the RS-232 mode of operation, install DIP shunts in sockets found
at E5 and E8. E5 sets Port 1 and E8 sets Port 2.
IRQ Selection
Headers E1 and E2 select the interrupt request for each serial port (E1–Port
2, E2–Port 1). If COM1: is selected, this jumper must be on the IRQ4 setting.
If COM2: is selected, this jumper must be on IRQ3.
NOTE
Most communications software applications default COM3: to IRQ4 and
COM4: to IRQ3. This requires the sharing of interrupts between COM1:
and COM3:, and between COM2: and COM4:. While this is the default, it
is not always the best setting. Check your software configuration
instructions to determine the most appropriate IRQ setting.
4. Option Selection

8
DUAL PORT RS-232↔422/485 SERIAL INTERFACE
Figure 4-1. Header E1 and E2 (IRQ selection).
Any two or more ports can share a common IRQ by placing the jumpers on
the same IRQ setting, and setting the appropriate selections at E9 and E10.
Consult your particular software for IRQ selection. If no interrupt is desired,
remove the jumper.
NOTE
IRQ 2 on AT class machines is not available. IRQ 9 is substituted in place
of IRQ 2. To select IRQ 9, place jumper in the IRQ 2 position.
Figure 4-2 shows Headers E9 and E10. “N” indicates the normal, single
interrupt per port mode. The “S” indicates the shared interrupt mode, which
allows more than one port to access a single IRQ. The “M” indicates that the
inclusion of a 1K-ohm pull-down resistor is required on one port when
sharing interrupts. E10 sets Port 1 and E9 sets Port 2.
E1
E2
2/9 3 4 5 7 10 11 12 15
2/9 3 4 5 7 10 11 12 15

9
CHAPTER 4: Option Selection
Figure 4-2. Headers E9 and E10 in Normal Mode.
Set jumpers to “N” for single interrupt mode. This setting is the normal
setting for most applications.
Set jumpers to “S” for shared interrupt mode for all ports sharing an IRQ
except one. Set that port block for “M.” This provides the pull-down resistor
circuit that makes sharing of IRQ’s possible. If you are using more than one Dual
Port RS-232/422/485 Serial Interface or a compatible card in a bus, you should only
have one port set to “M.”
Set jumpers to “S” if you are using more than one Dual Port
RS-232/422/485 in a bus or if you wish to completely remove the pull-down
resistor for hardware compatibility. Setting the board in this configuration
when it is not accompanied by a pull-down resistor will prevent the ports from
triggering an interrupt.
4.2 RS-232 Interface Options
To select the RS-232 mode of operation, install DIP shunts in the sockets
found at E5 and E8. E5 sets Port 1 and E8 sets Port 2. These DIP shunts are
completely independent of each other, allowing the user to select a single-
port RS-232 or a single-port RS-422.
There are no modem control options for the RS-232 interface: all control
signals are implemented. If your software requires certain handshaking
signals to be active, then you must connect them either to the device with
which you are communicating or you can satisfy the handshake signal
requirements by connecting pins 7 to 8 (RTS to CTS) and pins 4 to 6 to 1
(DTR to DSR & DCD). Make these connections on the DB9 connector that
connects to each port. Refer to Figure 4-3 when making these connections.
(The table on page 4 lists the RS-232 pinout descriptions.)
N S M

10
DUAL PORT RS-232↔422/485 SERIAL INTERFACE
Figure 4-3. DB9 Handshake Loopback connections for RS-232
(shown from rear or cable side of connector).
4.3 RS-422/485 Interface Options
To select the RS-422/485 mode of operation, install DIP shunts in the sockets
found at E6 and E7. E6 sets Port 1 and E7 sets Port 2.
Figure 4-4 shows Headers E3 and E4. Position “A” determines whether the
RS-485 driver is enabled by the UART signal Request To Send (RTS) or always
enabled. With the jumper installed in position “A,” RTS enables the driver.
Removing the jumper enables the driver, regardless of RTS. E4 sets Port 1
and E3 sets Port 2. This jumper should be set to “A” only if you are running
the board in a multidrop polled environment such as RS-485, and you have
software that “knows how to talk” on the RS-485 bus. For normal point-to-
point RS-422 (such as terminal emulation), make sure that a jumper at
position “A” is not in place.
Positions “B” and “C” determine whether the board provides a direct ground
connection (as in RS-232 and most RS-422), or a 100-ohm high-impedance
ground. The high-impedance ground is normally used by
RS-485 (and some RS-422) to avoid ground-loop currents with long cables.
Position “B” selects the direct ground, and position “C” selects the 100-ohm
high-impedance ground. “C” should be selected when RS-422/485 operation
is selected.
5 4 3 2 1
9 8 7 6

11
CHAPTER 4: Option Selection
Figure 4-4. Headers E3 and E4, RS-485 Enable/Ground Selection.
4.4 Line Termination
Typically each end of the RS-422/485 bus must have line-terminating
resistors. A 100-ohm resistor is across each RS-422/485 input, and a 1K-ohm
pull-up/pull-down combination biases the receiver inputs. If more than two
RS-485 nodes are configured in a multidrop network, only the nodes at each
end of the bus should have the 100-ohm resistors installed.
A B C

12
DUAL PORT RS-232↔422/485 SERIAL INTERFACE
The Dual Port RS-232/422/485 can be installed in any of the PC expansion
slots, except J8 on the original IBM XT®and Portable.
IMPORTANT
You MUST set up the operating system BEFORE you physically install
the Card.
5.1 Software Installation
If you are installing an ISA adapter in DOS, OS/2®, or QNX, please refer to the
appropriate directory on one of the Serial Utilities Disks for instructions.
5.1.1 W INDOWS 3.1
X
Please refer to the /WINDOWS sub-directory on the Serial Utilities Diskette for
help files and current information on the installation of the Card in this operating
environment.
5.1.2
W INDOWS 95/98 U
SERS
For the ISA card, run setup on disk two of the Serial Utilities Diskettes before
installing the card. Make note of the resources that Windows assigns the adapter,
and set the adapter to match those resources. Power down the computer and
install the adapter as described in Section 5.2. If you wish to change any resources
assigned to the adapter, refer to the help file installed in the Black Box folder in
the Start, Programs menu.
5.1.3 W INDOWS NT
For the ISA card, run setup on disk two of the Serial Utilities Diskettes before
installing the card. After installing the software, refer to the help file that
automatically comes up for installation instructions.
5. Installation

13
CHAPTER 5: Installation
5.2 Hardware Installation
The ISA Card can be installed in any of the PC expansion slots. The Card contains
several jumper straps for each port that you must set for proper operation.
1. Turn off PC power. Disconnect the power cord.
2. Remove the PC case cover.
3. Locate an available slot and remove the blank metal slot cover.
4. Gently insert the Card into the slot. Make sure that the Card is seated
properly.
5. Replace the screw.
6. Replace the cover.
7. Connect the power cord.
Installation is complete.
Self-Test
To perform a self-test on the card, connect the transmit and receive data pins
together. If running 422/485, make sure the plus leads are not connected to
the minus leads. Execute the SLT program provided on the supplied utility
diskette.

14
DUAL PORT RS-232↔422/485 SERIAL INTERFACE
E6
E5
U13
E7E8
U12
C9
C10
P1
P3
C8
U11 RP2 RP3 C7
U9
RP4
R8
U18 U8
R9
U6 U7
PORT1 PORT2
R5R4R4
E10E9
D1
PORT1
PORT2 E2
E1
P2
P6
U2
C2
U1
R2
SW2
R1
SW1
C1
V1
PORT1 PORT2
C3
PORT1 PORT2
C1 C5
U4 U5
U3 C6 RP1 PORT2
E3
PORT1
E4
R6
R7
422/485 PORT 2 RS-232 PORT 2 RS-232 PORT 1 422/485 PORT 1
J1 PORT 1J1 PORT 2
1
65 91 65 9
2
3
4
5
6
10
11
12
15
2
3
4
5
6
10
11
12
15
R3 D2 A
B
C
A
B
C
Appendix: Circuit-Board Design

15
P1 A11 AEN
WR/
RD/
B4
D3 D5
A8 A6 A4
AEN
A3 A5 A7 A9
2 4 6 8
11
13 15 17
P0 P1 P2 P3 P4 P5 P6 P7
U1
A9 A8 A7 A6 A5 A4 A3
15 13
11
10 12 14 16
SW1 SW1 SW1 SW1 SW1 SW1 SW1
2 4 6 7 5 3 1
P1 P1 P1 P1 P1 P1 P1
A22 A23 A24 A25 A26 A27 A28
P1 P1 P1 P1
B2
A31 A30 A29
P1 P1
B13 B14
RESET
A0 A1 A2
D0 D1 D2 D3 D4 D5 D6 D7
A9 A8 A7 A6 A5 A4 A3 A2
P1 P1 P1 P1 P1 P1 P1 P1 P1 P1 P1 P1 P2 P2 P1 P2 P2
B21 D4 D6
B25 B24 B23
IRQ10 IRQ12
IRQ2 IRQ3 IRQ4 IRQ5
IRQ7
IRQ11
IRQ15
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
3 5 7 9
12 14 16 18
GND
74LS682
GND
GND
VDO
P=Q P>Q
VSS
R1
20
19
1
10
+5V
+5V
12
98SW1
A8 A6 A4
AEN
A3 A5 A7 A9
2 4 6 8
11
13 15 17
P0 P1 P2 P3 P4 P5 P6 P7
U2
15 13
11
10 12 14 16
SW2 SW2 SW2 SW2 SW2 SW2 SW2
2 4 6 7 5 3 1
Q0 Q1 Q2 Q3 Q4 Q5 Q6 Q7
3 5 7 9
12 14 16 18
GND
74LS682
GND
GND
VDO
P=Q P>Q
VSS
R2
20
19
1
10
+5V
+5V
12
98SW2
1
74LS125A
R5 U6
GND
23
4
74LS125A
U6
GND
56
12
+5V
U3
13
74LS125A
U6
1211 10
74LS125A
U6
98
E1
2 4 6 8
10 12 14 16 18
1 3 5 7 9
11
13 15 17
E2
2 4 6 8
10 12 14 16 18
1 3 5 7 9
11
13 15 17
R3
1
2
GND
D1
12
E9
4
3
2
1
R4
1
2
GND
D2
12
E10
4
3
2
1
P1 P1 P1
B9 B3
B29
+12V +5V +5V
+5V
RP1
1 6
RP1
1 2
RP1
1 4
U12
74LS245
A2 A3 A4 A5 A6 A7 A8
3 4 5 6 7 8 9
B2 B3 B4 B5 B6 B7 B8
17 16 15 14 13 12
11
BD1 BD2 BD3 BD4 BD5 BD6 BD7
A1
2B1 18 BD0
GND +5V
SHEET 1 10
20
1
19
VSS
VDO
DIR G
BRD
U3
HC244
A1 A2 A3 A4
11
13 15 17
Y1 Y2 Y3 Y4
9 7 5 3
BWR/ BRD/
GND
10
19 VDO/VSS
G
GND
HC244
A1 A2 A3 A4
2 4 6 8
Y1 Y2 Y3 Y4
18 16 14 12
BRESET
BA0 BA1 BA2
+5V
20
1VDO/VSS
G
+12V
+5V
GND
P1 P1
B1
B31
GND GND
1 2
C10 C8
1
2 3
C1
1
2 3
C4
1
2 3
C5
1
2 3
C2
1
2 3
C3
1
2 3
P1 B7 -12V -12V +5V
GND
C9
1
2 3
C7
1
2 3
C6
1
2 3
U4
8250A
D0 D1 D2 D3 D4 D5 D6 D7 DTR RTS OUT1 OUT2 CSOUT DDIS BAUDOUT INTRPT SOUT
1 2 3 4 5 6 7 8
33 32 34 31 24 23 15 30
11
XTAL1 XTAL2
MR
CS0 CS1 CS2
DISTR DISTR
DOSTR DOSTR
ADS
RCLK
SIN
CTS
DSR
DCD
RI
A0 A1 A2
16 17 35 12 13 14 22 21 19 18 25
9
10 36 37 38 39 28 27 26
BD0 BD1 BD2 BD3 BD4 BD5 BD6 BD7
GND
+5V 20
40
VSS
VDO
GND
+5V
BRESET
BRD/ BWR/
BA0 BA1 BA2
RD1
CTS1
DSR1
DCD1
RI1
SHEET 2
SHEET 2 SHEET 2
DTR1 RTS1
TD1
U5
8250A
D0 D1 D2 D3 D4 D5 D6 D7 DTR RTS OUT1 OUT2 CSOUT DDIS BAUDOUT INTRPT SOUT
1 2 3 4 5 6 7 8
33 32 34 31 24 23 15 30
11
XTAL1 XTAL2
MR
CS0 CS1 CS2
DISTR DISTR
DOSTR DOSTR
ADS
RCLK
SIN
CTS
DSR
DCD
RI
A0 A1 A2
16 17 35 12 13 14 22 21 19 18 25
9
10 36 37 38 39 28 27 26
BD0 BD1 BD2 BD3 BD4 BD5 BD6 BD7
GND
+5V 20
40
VSS
VDO
GND
+5V
BRESET
BRD/ BWR/
BA0 BA1 BA2
RD2
CTS2
DSR2
DCD2
RI2
SHEET 2
SHEET 2 SHEET 2
DTR2 RTS2
TD2
GND
+5V
VSS
VDO
TXCO
NC
OUT
Y1
114 78
APPENDIX: Circuit-Board Design