ACCESS I/O PRODUCTS ASSURED SYSTEMS 104-COM-8SM User manual

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PC/104 2, 4 & 8-Port RS-232/422/485 Serial
Communication Boards
This is an eight-, four-, or two-port, asynchronous, serial communication board designed for use on the PC/104 bus. It
supports RS-232, RS-422 or RS-485 communications. The board may be installed in any standard PC/104 stack. Connections
are made via two 40 pin IDC type right angle connectors. Common applications include POS, gaming systems, machine
monitoring, military and high-density networking. Type 16780 UARTS are used as the asynchronous communication
elements. These include 64-byte transmit/receive FIFO buffers to protect against lost data in multitasking systems while
maintaining 100% compatibility with the original IBM serial port (software compatible with Windows COM port drivers). A
crystal oscillator located on the board permits precise baud rate capability up to 115,200. Higher speeds, up to 921.6K, are
achieved by installing a jumper on the board. The addresses of the individual channels and IRQ are stored in non volatile
memory on the board and loaded into programmed logic when the board is initially powered. AUTO TRANSCEIVER CONTROL
In RS-485 multidrop communications individual drivers must be enabled when needed and then disabled after use to permit
all ports on the network to share a two-wire or four-wire cable. The 104-COM-8SM and 104-COM4SM use an automatic
(AUTO) control software selectable channel by channel. The driver is enabled (and the receiver disabled) when data is ready
to be transmitted. When transmission is complete, the driver remains enabled for the transmission time of one additional
character and then is disabled. This is ideal for use in Windows based applications as the standard Windows COM port
driver is used to ensure compatibiliy. UTILITY SOFTWARE Tools provided include samples to demonstrate COM port
initialization in multiple languages. Driver software is provided by Windows and all other major operating systems, including
Linux (16550 compatible.) A graphical Setup program is provided to assist with jumper selections for protocol and address
configuration.

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Description
This is an eight-, four-, or two-port, asynchronous, serial communication board designed for use on the PC/104 bus. It
supports RS-232, RS-422 or RS-485 communications. The board may be installed in any standard PC/104 stack. Connections
are made via two 40 pin IDC type right angle connectors. Common applications include POS, gaming systems, machine
monitoring, military and high-density networking. Type 16780 UARTS are used as the asynchronous communication
elements. These include 64-byte transmit/receive FIFO buffers to protect against lost data in multitasking systems while
maintaining 100% compatibility with the original IBM serial port (software compatible with Windows COM port drivers). A
crystal oscillator located on the board permits precise baud rate capability up to 115,200. Higher speeds, up to 921.6K, are
achieved by installing a jumper on the board. The addresses of the individual channels and IRQ are stored in non volatile
memory on the board and loaded into programmed logic when the board is initially powered. AUTO TRANSCEIVER CONTROL
In RS-485 multidrop communications individual drivers must be enabled when needed and then disabled after use to permit
all ports on the network to share a two-wire or four-wire cable. The 104-COM-8SM and 104-COM4SM use an automatic
(AUTO) control software selectable channel by channel. The driver is enabled (and the receiver disabled) when data is ready
to be transmitted. When transmission is complete, the driver remains enabled for the transmission time of one additional
character and then is disabled. This is ideal for use in Windows based applications as the standard Windows COM port
driver is used to ensure compatibiliy. UTILITY SOFTWARE Tools provided include samples to demonstrate COM port
initialization in multiple languages. Driver software is provided by Windows and all other major operating systems, including
Linux (16550 compatible.) A graphical Setup program is provided to assist with jumper selections for protocol and address
configuration.

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Website Specification
8, 4, or 2 independent asynchronous serial COM ports
Field selectable RS-232, RS-422 and RS-485, independent for each port
Auto-RTS feature makes half-duplex RS-485 communications effortless
Speeds up to 921.6K with 64-byte FIFO (RS-232 is 230K max)
Fixed bias and jumper selectable termination provided on each transmit and receive channel simplifies cabling
Programmable individual non-volatile base addresses and IRQs simplifies installation
Low power required: +5VDC at 80 mA typical
Operates as a standard COM port in all operating systems
Factory Options: (call for pricing and availability)
0 to 70 C and -40 to +85 C versions available
4 port version available

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KEY FEATURES:
■ 8, 4, or 2 independent asynchronous serial COM ports■ Field selectable RS-232, RS-422 and RS-485, independent for each port■ Auto-RTS feature makes half-duplex RS-485 communications effortless■ Speeds up to 921.6K with 64-byte FIFO■ Fixed bias and jumper selectable termination provided on each transmit and receive channel simplifies cabling■ Programmable individual non-volatile base addresses and IRQs simplifies installation■ Low power required: +5VDC at 80mA typical ■ Operates as a standard COM port in all operating systems
FACTORY OPTIONS:
■ 0 to 70°C and -40 to +85°C versions available■ 128-byte FIFO
104-COM-8SM 104-COM-4SM104-COM-2SM8-, 4-, or 2-Port RS-232/422/485 PC/104 SERIAL COMMUNICATION
The 104-COM-8SM Series are eight, four, or two-port, asynchronous, serial communication boards that support field selectable RS-232/422/485 communication. Ports are accessed via two 40-pin IDC type right angle header connectors. The boards include a convenient Auto-RTS feature, which makes half-duplex RS-485 communications effortless. The 104-COM-8SM Series are feature-rich and allow for the connection of multiple serial devices—ideal for a variety of applications such as POS, gaming systems, machine monitoring and control, military, high-density networking applications or any other application requiring the connection of RS-232/422/485 serial devices to a PC/104 compatible system. The 104-COM-8SM Series were designed using type 16780 UARTS and include 64-byte transmit/receive FIFO buffers to protect against lost data in multi-tasking systems while maintaining 100% compatibility with all operating system COM port drivers. A crystal oscillator located on the board permits baud rate capability up to 921.6K. The boards are offered in both standard and extended temperature versions - ideal for outdoor applications or harsh industrial surroundings.
SOFTWARE
The 104-COM-8SM Series are supported for use in all operating systems and include a free DOS, Linux and Windows 95/98/Me/NT/2000/XP/2003 compatible software package. This contains sample programs and source code in "C" and Pascal for DOS, and Visual Basic, Delphi, C++ Builder, and Visual C++ for Windows. Also included is a graphical setup program in Windows. Embedded OS support includes Windows XPe and CE. An easy-to-use Windows terminal program simplifies verification of proper operation.ACCES I/O Products, Inc. 10623 Roselle Street San Diego, CA 92121 Tel: [phone] [phone] Fax: [phone] Email: [e-mail] Website: www.accesio.com
ACCES
I/O PRODUCTS, INC.

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8-, 4-, or 2-Port RS-232/422/485 PC/104 SERIAL COMMUNICATION 104-COM-8SM 104-COM-4SM104-COM-2SMSerial Ports
Number of serial ports 8, 4, or 2Protocol Full RS-232, RS-422 and RS-485, independent for each portMaximum baud rate 921.6KCharacter length 5, 6, 7, or 8 data bitsParity Even, odd, or noneReceiver input sensitivity ±200mV differential input. Lines include factory bias and jumper selectable termination.Common mode +12V to -7V voltage rangeTransmitter output 60mA with thermal shutdown. Lines include drive capability factory bias and jumper selectable termination.Base address options ProgrammableInterrupts Individual IRQs for each channel are stored onboard in non-volatile memory
General
I/O connections Via two 40 pin IDC type right angle connectors. There are eight pins per port plus common grounds.Short circuit protection All outputs protected against continuous short circuitPower required +5VDC at 80mA typical, all outputs openOperating temperature -40 to +85°C optional, all versionsOperating humidity 5% to 95% RH, non-condensingPC/104 bus 8-bit and 16-bit bus headers are used
SpecificationsBlock Diagram & Pin Configuration Ordering Guide
ACCES
I/O PRODUCTS, INC.
ACCES I/O Products, Inc. 10623 Roselle Street San Diego, CA 92121 Tel: [phone] [phone] Fax: [phone] Email: [e-mail] Website: www.accesio.com© Copyright 2005 ACCES I/O Products, Inc. Specifications subject to change without notice.104-COM-8SM 8-port RS-232/422/485104-COM-4SM 4-port RS-232/422/485104-COM-2SM 2-port RS-232/422/485
NCPORT0-Tx/Rx+NCNCPORT0-GNDNCPORT1-Tx/Rx+NCNCPORT1-GNDNCPORT2-Tx/Rx+NCNCPORT2-GNDNCPORT3-Tx/Rx-NCNCPORT3-GNDNCPORT0-Tx/Rx-NCNCNCNCPORT1-Tx/Rx-NCNCNCNCPORT2-Tx/Rx-NCNCNCPORT3-Tx/Rx+NCNCNCNC0201
03040506
07080910
1112
1314
151617181920
21222324
2526
2728
29303132333435363738
3940NCPORT0-Tx+NCPORT0-Rx+PORT0-GNDNCPORT1-Tx+NCPORT1-Rx+PORT1-GNDNCPORT2-Tx+NCPORT2-Rx+PORT2-GNDNCPORT3-Tx-PORT3-Rx-NCPORT3-GNDNCPORT0-Tx-PORT0-Rx-NCNCNCPORT1-Tx-PORT1-Rx-NCNCNCPORT2-Tx-PORT2-Rx-NCNCPORT3-Tx+NCPORT3-Rx+NCNC0201
03040506
07080910
1112
13141516
1718
1920
2122232425262728
2930
3132
33343536
3738
3940RS-422 Functions
PORT0-DCDPORT0-RxPORT0-TxPORT0-DTRPORT0-GNDPORT1-DCDPORT1-RxPORT1-TxPORT1-DTRPORT1-GNDPORT2-DCDPORT2-RxPORT2-TxPORT2-DTRPORT2-GNDPORT3-DCDPORT3-RxPORT3-TxPORT3-DTRPORT3-GNDPORT0-DSRPORT0-RTSPORT0-CTSPORT0-RINCPORT1-DSRPORT1-RTSPORT1-CTSPORT1-RINCPORT2-DSRPORT2-RTSPORT2-CTSPORT2-RINCPORT3-DSRPORT3-RTSPORT3-CTSPORT3-RINC0201
0304
0506
0708
0910
1112
1314
1516
1718
1920
21222324
2526
2728
2930
3132
333435363738
3940RS-232 FunctionsRS-485 Functions

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10623 Roselle Street, San Diego, CA 92121 [phone] Fax [phone]
[e-mail] www.accesio.com
EIGHT, FOUR, OR TWO-PORT
RS-232/422/485 PC/104
SERIAL COMMUNICATION BOARD
MODELS 104-COM-8SM (4SM, 2SM)
USER MANUAL
file: M104-COM-8SM.C12

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Manual 104-COM-8SM
2
Notice
The information in this document is provided for reference only. ACCES does not assume any liability arising out of
the application or use of the information or products described herein. This document may contain or reference
information and products protected by copyrights or patents and does not convey any license under the patent
rights of ACCES, nor the rights of others.
IBM PC, PC/XT, and PC/AT are registered trademarks of the International Business Machines Corporation.
Printed in USA. Copyright 2003, 2005 by ACCES I/O Products, Inc. 10623 Roselle Street, San Diego, CA 92121.
All rights reserved.
WARNING!!
ALWAYS CONNECT AND DISCONNECT YOUR FIELD CABLING WITH THE
COMPUTER POWER OFF. ALWAYS TURN COMPUTER POWER OFF
BEFORE INSTALLING A BOARD. CONNECTING AND DISCONNECTING
CABLES, OR INSTALLING BOARDS INTO A SYSTEM WITH THE COMPUTER
OR FIELD POWER ON MAY CAUSE DAMAGE TO THE I/O BOARD AND WILL
VOID ALL WARRANTIES, IMPLIED OR EXPRESSED.

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Manual 104-COM-8SM
3
Warranty
Prior to shipment, ACCES equipment is thoroughly inspected and tested to applicable specifications. However,
should equipment failure occur, ACCES assures its customers that prompt service and support will be available. All
equipment originally manufactured by ACCES which is found to be defective will be repaired or replaced subject to
the following considerations.
Terms and Conditions
If a unit is suspected of failure, contact ACCES' Customer Service department. Be prepared to give the unit model
number, serial number, and a description of the failure symptom(s). We may suggest some simple tests to confirm
the failure. We will assign a Return Material Authorization (RMA) number which must appear on the outer label of
the return package. All units/components should be properly packed for handling and returned with freight prepaid
to the ACCES designated Service Center, and will be returned to the customer's/user's site freight prepaid and
invoiced.
Coverage
First Three Years: Returned unit/part will be repaired and/or replaced at ACCES option with no charge for labor or
parts not excluded by warranty. Warranty commences with equipment shipment.
Following Years: Throughout your equipment's lifetime, ACCES stands ready to provide on-site or in-plant service
at reasonable rates similar to those of other manufacturers in the industry.
Equipment Not Manufactured by ACCES
Equipment provided but not manufactured by ACCES is warranted and will be repaired according to the terms and
conditions of the respective equipment manufacturer's warranty.
General
Under this Warranty, liability of ACCES is limited to replacing, repairing or issuing credit (at ACCES discretion) for
any products which are proved to be defective during the warranty period. In no case is ACCES liable for
consequential or special damage arriving from use or misuse of our product. The customer is responsible for all
charges caused by modifications or additions to ACCES equipment not approved in writing by ACCES or, if in
ACCES opinion the equipment has been subjected to abnormal use. "Abnormal use" for purposes of this warranty is
defined as any use to which the equipment is exposed other than that use specified or intended as evidenced by
purchase or sales representation. Other than the above, no other warranty, expressed or implied, shall apply to any
and all such equipment furnished or sold by ACCES.

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Manual 104-COM-8SM
4
TABLE OF CONTENTS
CHAPTER 1: FUNCTIONAL DESCRIPTION .............................................................................. 5
Figure 1-1: BLOCK DIAGRAM.............................................................................................................................7
CHAPTER 2: INSTALLATION..................................................................................................... 8
CHAPTER 3: OPTION SELECTION.......................................................................................... 13
Figure 3-1: Simplified Dynamic Termination Schematic ....................................................................................13
Figure 3-2: OPTION SELECTION MAP ............................................................................................................16
CHAPTER 4: ADDRESS SELECTION ...................................................................................... 17
Table 4-1: Standard Address Assignments for Computers................................................................................17
CHAPTER 5: PROGRAMMING ................................................................................................. 19
Table 5-1: Control Block Register Map ..............................................................................................................19
Table 5-2: EEPROM Address Map ....................................................................................................................19
Table 5-3: BAUD RATE DIVISOR VALUES ......................................................................................................22
CHAPTER 6: CONNECTOR PIN ASSIGNMENTS.................................................................... 25
PIN CONNECTIONS Connector P2 (8-port and 4-port boards).........................................................................25
PIN CONNECTIONS Connector P3 (8-port board only) ....................................................................................26
CHAPTER 7: SPECIFICATION ................................................................................................. 27
APPENDIX A.............................................................................................................................. 28
Table A-1: RS-422 SPECIFICATION SUMMARY .............................................................................................29

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Manual 104-COM-8SM
5
CHAPTER 1: FUNCTIONAL DESCRIPTION
This serial Interface board contains eight independent ports and provides effective RS-485, RS-422 and RS-232
multipoint communication. The 4SM board contains four such ports and the 2SM has two ports. Each channel may
be configured to any mode. Jumpers on the board, along with the proper entries into the EEPROM, permit the
choice of configuration, including termination, for each individual channel.
This series of boards are designed in the PC/104 format. The dimensions are approximately 3.775 inches X 3.550
inches. All signal connections are made through two 40 pin connectors, mounted on edges of the board.
In RS-422 or RS-485 modes, the board can achieve speeds up to 921.6kbps per port. In RS-232 mode, the
maximum speed is 230kbps.
RS-485 BALANCED MODE OPERATION
The board supports RS-485 modes that use differential balanced drivers for increased range and noise immunity.
The RS-485 specification defines a maximum of 32 devices on a single line. The number of devices served on a
single line can be expanded by use of “repeaters”.
The board also has the capability to add load resistors to terminate the communications lines. RS-485
communications requires that one transmitter supply a bias voltage to ensure a known “zero” state when all
transmitters are off. Also, receiver inputs at each end of the network should be terminated to eliminate “ringing”. The
board supports biasing by default and supports termination by jumpers on the board. If your application requires the
transmitter to be un-biased, please contact the factory.
The driver/receiver used, type 75176B, is capable of driving extremely long communication lines at high baud rates.
It can drive up to ±60 mA on balanced lines and receive inputs as low as 200 mV differential signal superimposed
on common mode noise of +12 V or -7 V. In case of communication conflict, the driver/receivers feature thermal
shutdown.
COM PORT COMPATIBILITY
A type 16C788 octal UART is used as the Asynchronous Communication Element (ACE). Each port includes a 64-
byte transmit/receive buffer to protect against lost data in multitasking operating systems, while maintaining 100%
compatibility with the original IBM serial port. However, the ports are not restricted to the standard COM port
addresses.
Continuous address selection is available anywhere within the I/O address range 100 to 3F8 hex, and our
FINDBASE program will scan I/O Bus memory-mapped addresses in your computer for available addresses that
can be used without conflicting with other computer resources. This allows a port to be used as one of the four
“standard” COM ports (COM1 to COM4), or to coexist alongside them, in any combination.
A crystal oscillator is located on the board. This oscillator permits precise selection of baud rate from 300 to 921,600
with the standard crystal oscillator. The standard crystal oscillator is used to generate two clock rates. One is a
1.8432MHz clock. The other is the 14.7456MHz clock which may be selected by installing the “X8" jumper.
COMMUNICATION MODES
The board supports Half-Duplex communications with a 2-wire cable connection. Half-Duplex allows traffic to travel
in both directions, but only one way at a time. RS-485 communications commonly use the half-duplex mode since
they share only a single pair of wires.

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Manual 104-COM-8SM
6
TRANSCEIVER CONTROL
In RS-485 communications, the transmitter must be enabled and disabled as needed, allowing all boards to share a
two wire cable.
The direction of communication is controlled through the RTS signal. The RTS signal is controlled by programming
the UART. The UART is controlled in the same manner as all series 16450 and 550 UARTs. Details on its operation
are included in the data sheet for the UART.
If it is desired to have the channel in the receive mode, it must be put into this mode by changing the mode, through
the RTS signal, upon completion of each transmission.
Similarly, the UART must be put into the transmit mode prior to transmitting.
IRQ SUPPORT
The board supports the use of IRQ resources, and includes an on-board IRQ status register for use with operating
systems that support this feature, such as Microsoft’s Windows NT.
The status register is located at an address of the COM A address + 400H.

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Manual 104-COM-8SM
7
PC/104 BUS
40 PIN HEADER
WITH
AUTO-RTS
CIRCUITRY
Figure 1-1: BLOCK DIAGRAM
(Only one serial channel shown)

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Manual 104-COM-8SM
8
CHAPTER 2: INSTALLATION
A printed Quick-Start Guide (QSG) is packed with the board for your convenience. If you’ve already performed the
steps from the QSG, you may find this chapter to be redundant and may skip forward to begin developing your
application.
The software provided with this PC/104 Board is on CD and must be installed onto your hard disk prior to use. To
do this, perform the following steps as appropriate for your operating system.
CD Installation
The following instructions assume the CD-ROM drive is drive “D”. Please substitute the appropriate drive letter for
your system as necessary.
DOS
1. Place the CD into your CD-ROM drive.
2. Type  to change the active drive to the CD-ROM drive.
3. Type  to run the install program.
4. Follow the on-screen prompts to install the software for this board.
WINDOWS
1. Place the CD into your CD-ROM drive.
2. The system should automatically run the install program. If the install program does not run promptly, click
START | RUN and type , click OK or press .
3. Follow the on-screen prompts to install the software for this board.
LINUX
1. Please refer to linux.htm on the CD-ROM for information on installing serial ports under linux.

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Manual 104-COM-8SM
9
Installing the Hardware
Before installing the board, carefully read Chapter 3 and Chapter 4 of this manual and configure the board
according to your requirements. The SETUP Program can be used to assist in configuring jumpers on the board.
Be especially careful with Address Selection. If the addresses of two installed functions overlap, you will
experience unpredictable computer behavior. To help avoid this problem, refer to the FINDBASE.EXE program
installed from the CD. The setup program does not set the options on the board, these must be set by jumpers.
This multi-port serial communication board uses software-programmable address ranges for each UART, stored in
an onboard EEPROM. Configure the address of the EEPROM using the onboard Address Selection jumper block,
then use the provided Setup program to configure addresses for each onboard UART.
To Install the Board
1. Install jumpers for selected options and base address according to your application requirements, as
mentioned above.
2. Remove power from the PC/104 stack.
3. Assemble standoff hardware for stacking and securing the boards.
4. Carefully plug the board onto the PC/104 connector on the CPU or onto the stack, ensuring proper
alignment of the pins before completely seating the connectors together.
5. Install I/O cables onto the board’s I/O connectors and proceed to secure the stack together or repeat steps
3-5 until all boards are installed using the selected mounting hardware.
6. Check that all connections in your PC/104 stack are correct and secure then power up the system.
7. Run one of the provided sample programs appropriate for your operating system that was installed from
the CD to test and validate your installation.
Installing COM Ports in Windows Operating Systems
*NOTE: COM boards can be installed in virtually any operating system and we
do support installation in earlier versions of windows, and are very likely to
support future version as well. For use in WinCE, contact the factory for specific
instructions.
Windows NT4.0
To install the COM ports in Windows NT4 you’ll need to change one entry in the registry. This entry enables IRQ
sharing on multi-port COM boards. The key is
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Serial\. The name of the value is PermitShare
and the data should be set to 1.
You’ll then add the board’s ports as COM ports, setting the base addresses and IRQs to match your board’s
settings.
To change the registry value, run RegEdit from the START|RUN menu option (by typing REGEDIT [ENTER] in the
space provided). Navigate down the tree view on the left to find the key, and double click on the name of the value
to open a dialog allowing you to set the new data value.

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Manual 104-COM-8SM
10
To add a COM port, use START|CONTROL PANEL|PORTS applet and click ADD, then enter the correct UART
address and Interrupt number.
When the “Add New Port” dialog is configured click OK, but answer “Don’t Restart Now” when prompted, until
you’ve added any other ports as well. Then restart the system normally, or by selecting “Restart Now.”
Windows XP
To install the COM ports in Windows XP you will be manually installing “standard” communications ports, then
changing the settings for resources used by the ports to match the hardware.
Run the “Add Hardware” applet from the Control Panel.
Click “Next” at the “Welcome to the Add New Hardware Wizard” dialog.
You’ll briefly see a “...searching...” message, then
Select “Yes, I have already connected the hardware” and Click “Next”
Select “Add a new hardware device” from the bottom of the list presented and Click “Next.”
Select “Install the hardware that I manually select from a list” and Click “Next.”
Select “Ports (COM & LPT) and Click “Next”
Select “(Standard Port Types)” and “Communications Port” (the defaults), Click “Next.”
Click “Next.”

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Manual 104-COM-8SM
11
Click the “View or change resources for this hardware (Advanced)” link.
Click the “Set Configuration Manually” button.
Select “Basic Configuration 8" from the “Settings Based on:” drop-down list.
Select “I/O Range” in the “Resource Settings” box and Click the “Change Settings...” button.
Enter the base address of the board, and Click “OK”

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Manual 104-COM-8SM
12
Select “IRQ” in the “Resource Settings” box and Click the “Change Settings” button.
Enter the IRQ of the board and Click “OK”.
Close the “Set Configuration Manually” dialog and Click “Finish.”
Click “Do Not Reboot” if you wish to install more ports. Repeat all of the above steps, entering the same IRQ but
using the configured Base address for each additional UART.
When you are done installing ports, reboot the system normally.

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Manual 104-COM-8SM
13
CHAPTER 3: OPTION SELECTION
To help you locate the jumpers described in this section, refer to the OPTION SELECTION MAP at the end of this
section, as well as running the SETUP.EXE utility program installed from the Software Master CD with the software
package for this board. That program also includes a function to program the port addresses (in Windows).
Operation of the serial communications section is determined by jumper installation as described in the following
paragraphs.
Figure 3-1: Simplified Dynamic Termination Schematic
TERMINATIONS:
A transmission line should be terminated at the receiving end in its characteristic impedance. Installing a jumper at
the location labeled TL or RL applies a 120Ω load in series with a small capacitor across the transmit/receive
input/output for RS-485 operation or input for RS-422 operation.
In RS-485 operations where there are multiple terminals, only the RS-485 ports at each end of the network should
have terminating resistors as described above. Also, for RS-485 operation, there must be a bias on the RX+ and
RX- lines. If the board is not to provide that bias, contact the factory technical support.

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Manual 104-COM-8SM
14
DATA CABLE WIRING
The following connections are used to communicate between two ports (usually on different devices), depending on
the communication mode:
Note that the user cable should include a ground to ground connection for RS-422 and RS-485 not just RS-232 as
high common mode between external devices will burn out the transceiver.
Cable Pins
Mode
Port 1
to
Port 2
RS-232
RX
to
TX
TX
to
RX
Ground
to
Ground
RS-485 Half-Duplex
TX/RX+
to
TX/RX+
TX/RX-
Ground
to
to
TX/RX-
Ground
RS-422 Full-Duplex
RX+
to
TX+
RX-
to
TX-
TX+
to
RX+
TX-
Ground
to
to
RX-
Ground
RS-422 Simplex Receive Only
RX+
to
TX+
RX-
Ground
to
to
TX-
Ground
RS-422 Simplex Transmit Only
TX+
to
RX+
TX-
Ground
to
to
RX-
Ground

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Manual 104-COM-8SM
15
INTERRUPTS: In addition to standard interrupt levels IRQ2 through IRQ7, the board also supports higher interrupts
IRQ10 through IRQ15 (Except those reserved by other installed hardware). The same interrupt is used for all
channels, it must be entered into the interrupt location in the EEPROM.
Please note: In Windows NT, changes must be made to the System Registry to support IRQ sharing. The following
is excerpted from “Controlling Multiport Serial I/O Boards” provided by Microsoft in the MSDN library.Document id:
mk:@ivt:nt40res/D15/S55FC.HTM, also available in the Windows NT Resource Kit. The text enclosed in brackets
(“[]”) denotes a comment by ACCES.
The Microsoft serial driver can be used to control many dumb multiport serial boards. Dumb indicates that the
control includes no on-board processor. Each port of a multiport board has a separate subkey under the
CurrentControlSet\Services\Serial subkey in the Registry. In each of these subkeys, you must add values for
DosDevices, Interrupt, InterruptStatus, Port Address, and PortIndex because these are not detected by the
Hardware Recognizer. (For descriptions and ranges for these values, see Regentry.hlp, the Registry help file on the
Windows NT Workstation Resource Kit CD.)
For example, if you have an eight-port COM board configured to use address 0x100 with an interrupt of 0x5, the
values in the Registry are: [assuming every port is configured to use the same IRQ, and the addresses are
configured to be consecutive and contiguous]
Serial2 subkey:
PortAddress = REG_DWORD 0x100
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM3
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 1
Serial3 subkey:
PortAddress = REG_DWORD 0x108
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM4
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 2
Serial4 subkey:
PortAddress = REG_DWORD 0x110
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM5
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 3
Serial5 subkey:
PortAddress = REG_DWORD 0x118
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM6
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 4
Serial6 subkey:
PortAddress = REG_DWORD 0x120
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM7
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 5
Serial7 subkey:
PortAddress = REG_DWORD 0x128
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM8
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 6
Serial8 subkey:
PortAddress = REG_DWORD 0x130
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM9
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 7
Serial9 subkey:
PortAddress = REG_DWORD 0x138
Interrupt = REG_DWORD 5
DosDevices = REG_SZ COM10
InterruptStatus = REG_DWORD 0x500
PortIndex = REG_DWORD 8