PCI-COM422/485 Series

User’s Manual

Measurement Computing Corporation
Revision 1, January, 2000
© Copyright 2000

HM PCI-COM422-485.DOC

ii

TABLE OF CONTENTS
1. INTRODUCTION

1

2. INSTALLATION

2

2.1 SOFTWARE INSTALLATION
2
2.2 FACTORY DEFAULT PORT CONFIGURATION:
2.3 HARDWARE INSTALLATION
3
2.4 SET UP THE COM PORT PARAMETERS
32

2.4.1 IF YOU ARE USING WINDOWS 95 OR 98:
3
2.4.2 IF YOU ARE USING WINDOWS NT:
3
2.4.3 TEST THE COM PORTS FOR PROPER OPERATION (COMAPP.EXE)

2.5 RS-485 AUTO-ENABLED MODE 6
2.6 EXTENDED BAUD RATE OPERATION 6
2.6.1 WINDOWS 95 OR 98 SPECIFIC CONFIGURATION
2.6.2 WINDOWS NT SPECIFIC CONFIGURATION 8
2.6.3 RESETTING CONFIGURATION ON POWER UP

78

3. HARDWARE CONNECTIONS 10
3.1 DB9F CONNECTIONS
10
3.2 PORT IDENTIFICATION 10
3.3 CHANGING THE COM PORT ASSIGNMENTS 10
3.4 STANDARD COM PORT CONFIGURATIONS 11
3.5 TERMINATION JUMPER SETTINGS
11

4. REGISTER MAP

12

4.1 REGISTER MAP OVERVIEW
4.2 REGISTER DESCRIPTIONS

12
12

4.2.1 INTERRUPT STATUS/CONTROL12
4.2.2 PORT 1 CLOCK SELECT / INTERRUPT STATUS
4.2.3 PORT 2 CLOCK SELECT / INTERRUPT STATUS

5. SPECIFICATIONS 15
6. TROUBLESHOOTING Q/A:

17

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13
13

5

This Page is blank intentionally .

iv

1. INTRODUCTION
The PCI-COM422/485 family consists of one and two port, RS-422 and RS-485-compatible, serial I/Oboards designed to operate in computers with PCI bus accessory slots. The package includes complete
software drivers for Windows 95, 98 and NT that allow the boards to be installed as a standard “COM”
port in your computer.
The boards are fully plug-and-play and provide an independent UART for each port. An easy to use set
up application program allows the user to choose between RS-422 and RS-485 operation as well as toenable the automatic transmitter enable mode in RS-485. The boards provide a maximum baud rate of
460.8 kbaud. All connections on the boards are made through DB9F connectors.
The available models are shown in the table below.

Board
PCI-COM422/485
PCI-COM422/485/S

Number of Ports
1
1

PCI-COM422/485/2
PCI-COM422/485/2/S

2
2

On-Board Surge
Suppression
No
Yes
No
Yes

1

FIFO
Depth
16 bytes
16 bytes
16 bytes
16 bytes2. INSTALLATION
2.1 SOFTWARE INSTAL LATION
Insert the PCI-COM CD into your CD drive. If your systems auto-run feature is enabled the PCI-COM
installation wizard will automatically launch.
If the installation wizard does not auto-launch, you can initiate the software installation by running the
program SETUP.EXE on the CD. Do this by locating the CD’s SETUP.EXE file in your Windows
Explorer and double clicking on it. Assuming your CD drive is the E: drive, SETUP.EXE will be in E:\
Follow the wizard’s instructions and accept the default settings if possible. An option is provided during
installation to copy an application that will restore the user settings after a reboot. This option should beinstalled if the board will be operated in a mode other than the factory default configuration shown below.

2.2 FACTORY DEFAULT PORT CONFIGURATION:
Mode
Transmit Control
Max Baud Rate

RS485
Auto Enabled
115.2K

If the PCI-COM422/485 board will be operated at either a higher baud rate or in RS422 mode then theconfiguration settings should be restored after reboot. This will prevent the end user from having to
manually reconfigure the hardware after each reboot (Figure 2-1).

Figure 2-1. Installation Option
Selecting yes to the above option during installation will cause the board settings to be stored in theregistry. When the computer is started the ComSet32.exe application will execute and restore the PCICOM422/485 hardware settings to their pre-shutdown state.

22.3 HARDWARE INSTAL LATIONThe PCI-COM422/485 boards are plug-and-play configured by the host operating system. There are noswitches for setting the base address or interrupt level. Configuration is controlled by your systems’
BIOS. To install the board, turn off your PC, unplug it, open it, and insert your PCI-COM422/485 board
into any available PCI slot.
To check that all ports have been properly installed you can interrogate the COM port system with thefollowing sequence:
If you are using Windows 95 or 98:
1.
2.
3.
4.

Right click on the “My Computer” Icon on your desktop.
Click on “Properties”.
Click on the “Device Manager” tab.
Double click on the “Ports (COM & LPT)” Icon
If you are using Windows NT:

1. Right click Start and then Settings on the Task Bar.
2. Click on “Control Panel”.
3. Click on the “Ports” icon.
The new PCI-COM ports should be listed.

2.4 SET UP THE COM PO RT PARAMETERS
2.4.1 IF YOU ARE USING WIND OWS 95 OR 98:
To set the RS422/485 port parameters (e.g. baud rate, parity) follow the sequence listed above
and then double click on the port you wish to configure. The Communications Port (COM#)
Properties sheet will appear. Click on the “Port Settings” tab and change the port settings tomatch your applications requirements. Click on the “Advanced” tab to select between RS422 andRS485 mode and to set the maximum baud rate clock. Figure 2-2 below shows the Advanced
setting screen for Windows 95/98.
When “Enable RS422 Mode” is selected, the RS485 mode settings are ignored. The settings fromthis page are saved in the system registry to support automatic reconfiguration after reboot.
2.4.2 IF YOU ARE USING WIND OWS NT:
To set the RS422/485 port parameters (e.g. standard baud rates, parity) use the Ports applet that canbe found in the Control Panel. Select the port you wish to configure and change the port settings tomatch your applications requirements. To configure the RS422/485 mode settings and to change
the maximum baud rate execute the control panel applet PCIcom. Figure 2-3 below shows theconfiguration screen that is displayed. The application supports the selection of RS422 or RS485
mode as well as maximum baud rate selection.

3

Figure 2-2. “Advanced” port settings tab for Windows 95/98.

Figure 2-3. PCIcom Control Panel Applet for Windows NT.

4

2.4.3 TEST THE COM PORTS FOR PROPER OPERATION (COMAPP.EXE)
An application is provided that allows you to test your installation by communicating with another
RS-422 or RS-485 serial port. This test application is called ComApp.exe, and was installed during yourdriver installation procedure. ComApp is a simple ASCII terminal emulator that automatically sends
whatever you type on the keyboard over the selected COM port, and automatically displays the data the
COM port receives.
You may use this application to test between two ports on the same PC, or install it on two PCs and test
communication between them. If you are installing a multi-port board, or you have a free RS-422 or RS485 port in addition to the one you are adding with the PCI–COM board, you can use the first method byrunning two instances of ComApp on the same PC.
If your COM port is connected to a simple ASCII controlled device, use ComApp to test for proper operation simply
by typing one or more commands, and watching how the external device responds.
To launch ComApp.exe you may either find the file using your explorer and double-click on it or, starting with your
Windows Start button, follow this order:Start

Î Programs Î ComputerBoards Î ComApp

Note: The above sequence assumes that the application was installed in the default “ComputerBoards”
folder. If you selected a different folder during installation then replace “ComputerBoards” with yourfolder name.
If you have a multi-port board, you can make a quick port communication test by connecting one port to another,and sending/reading data between the two ports.
To do this test you will need to connect the two ports together. In RS422 mode the receive pair (Pins 6 and 7) must
be connected to the transmit pair (Pins 8 and 9).
Port 1
Port 2
6 --------------------------- 8
7 --------------------------- 9
8 --------------------------- 6
9 --------------------------- 7
RS485 is a half-duplex protocol and thus transmits and receives over the same pair of wires. For RS485 thefollowing connection will suffice to test the installation.
Port 1
Port 2
8 ---------------------------- 8
9 ---------------------------- 9This serves to connect the transmit pins from one port to the receive pins of the other and vice versa. To perform thetest, follow the instructions below:
1. Connect the two ports as indicated above
2. Launch the ComApp program (as described above)
3. Select the Settings menu block and configure the first port. Figure 2-4 shows the settings dialog that will
be displayed.

5

Figure 2-4. TTY Settings

4. Launch the ComApp again. You will get a second ComApp window. Go to the Settings
menu and configure the second port. Note that you must use the same settings on both
ports for this test to work properly.
5. On both open ComApp windows, go to the Action menu and select Connect.
6. After connection, move the cursor to either ComApp window. Whatever is typed in thatwindow should be immediately displayed in the other. You can also test port
operations by selecting the Transfer menu and clicking on Send Data Block. A large
block of ASCII characters will automatically be sent, and should appear on the other

ComApp window. The transfer block can be used to send ASCII characters or hex numbers inuser defined block sizes.

2.5 RS-485 AUTO-ENABL ED MODE
The PCI-COM422/485 board incorporates a software selectable “Auto-Enable” mode. This mode can beused for applications that require reduced software overhead or to remove the burden of flow control
from the application itself. The Auto-Enable mode can be used for the transmission of single characters orfor block transfers of multiple characters in RS485 mode.
When using Auto-Enable mode, the PCI-COM485’s on-board state machine enables the transmitter’s
output driver once the falling edge of a start bit is detected. The length of time the output driver is enabled
is dependent on the combination of start, data, parity and stop bits the user selects.
Note: The user can select from any combination of start, data and parity bits, although this mode does
limit the transmission to a single stop bit (1.5 and 2 stop bits are not allowed in this mode and if used will
result in data integrity errors).

2.6 EXTENDED BAUD R ATE OPERATION
Though it isn’t possible to set baud rates greater than 115.2 kbaud on the PCI-COM series using the standard
Windows Communications Port Properties dialog, the board and operating system are actually capable of operating
at transfer rates up to 460.8 kbps. The PCI-COM series boards have a programmable divider between the on-board
system clock and the UART. This divider can be set using the Advanced tab that was added to the Windows 95/98
Communications Port Properties dialog or the PCIcom applet added to the NT Control Panel during the PCI-COM
software installation.
6

If the divider is set to divide by four, (the default setting) the board’s baud rate is exactly as Windows sets it. If thedivider is set to divide by two, the actual board baud rates become double what Windows has set them to. If thedivider is set to divide by one, the board’s baud rate is four times the baud rate set in Windows. These selections are
summarized in the table below.
UART
Clock Rate Divider
1.8432 MHz
4 (default)
3.6864 MHz
2
7.3728 MHz
1

Windows
ActualSetting baud rate
115.2 kbps
115.2 kbps
115.2 kbps
230.4 kbps
115.2 kbps
460.8 kbps

Note: Please pay very careful attention to your baud rate selections when using the extended baud rate operating
modes. The baud rate you select in windows will not be the actual baud rate setting of the PCI-COM board, and it iseasy to get confused regarding the speed at which the system is actually running.

2.6.1 WINDOWS 95 OR 98 SPEC IFIC CONFIGURATION
Extended baud rate operation is set on the COM port’s property page. To change to the enhanced baud rate
operating modes follow this procedure.
1.
2.
3.
4.
5.
6.
7.

Right click on the “My Computer” Icon on your desktop.
Click on “Properties”.
Click on the “Device Manager” tab.
Double click on the “Ports (COM & LPT)” Icon.
Double click on the port you wish to configure.
Click on the “Advanced” tab.
Select the desired UART clock rate from the radio buttons as shown in Figure 2-5:

Figure 2-5. PCI-COM422/485 (Port1) (COM3) Properties Screen Display
72.6.2 WINDOWS NT SPECIFIC CONFIGURATION
Extended baud rate operation is set by the control panel applet PCIcom. To change to the enhanced baud rate
operating modes, follow this procedure:

1.
2.
3.
4.

Right-click Start, then Settings on the Task Bar.
Click on “Control Panel”.
Click on the “PCIcom” icon.
Select the desired maximum clock rate from the dialog shown in Figure 2-6 below.

Figure 2-6. Windows NT PCIcom dialog

2.6.3 RESETTING CONFIGUR ATION ON POWER UP
The PCI-COM board will power up with the mode set to RS485 and UART Clock Rate set to 1.8432 MHz. If youchange the UART Clock Rate or mode via the Device Manager Property Page, you must execute the ComSet32.exe
application to restore the settings after a reboot. The Device Manager configuration dialog writes the chosen settings
to the registry. The ComSet32.exe application reads the settings from the registry and restores the PCI-COM
hardware configuration.
During installation, the user has the option to install a shortcut to the ComSet32.exe in the Startup folder. If you
select this option, (see Figure 2-1) your PCI-COM422/485 hardware configuration is maintained across reboots. If
you select NO, at each reboot the PCI-COM422/485 board is restored to its default configuration.
Note: The default settings for the hardware are RS485 mode with rates up to 115.2 kbaud.
If you selected NO during installation, when prompted about installing the ComSet32.exe, then you can manuallycreate a shortcut and copy it to your Startup menu. The ComSet32.exe application is installed in the directory
specified during installation. The default installation directory is C:\cb. To create a shortcut do the following:
1.
2.
3.
4.

Start the “Windows Explorer” application and open the installation directory.
Right click on the “ComSet32.exe” entry.
Select the “Create Shortcut” option from the drop down menu.
Under Windows 95/98: Copy the shortcut to the Startup folder(C:\Windows\Start Menu\Programs\Startup).

85.

Under Windows NT: Copy the shortcut to the general Startup folder(C:\Windows\Profiles\All Users\Start Menu\Programs\Startup)

To keep the ComSet32.exe window from popping up during execution, set the shortcut to execute minimized. To set
this option, do the following:
1. Right-click on the shortcut icon and select Properties.
2. Select the shortcut tab.
3. Set the option labeled Run to “Minimized”.

93. HARDWARE CONNECTIONSThe PCI-COM422/485 series provides 9-pin female “D” (DB9M) connectors that extend through the
backplate of the board.

3.1 DB9F CONNECTION S
The connectors on the PCI-COM422/485 boards provide the pin-out shown in Figure 3-1 below. Theview shown is looking into the connector.

1

GND

6

2

RTS+

7

3

RTSCTS+

4
5

CTS-

RX+
RX-

8

TX+

9

TX-

Figure 3-1. PCI-COM422/485 Connector Pinout

3.2 PORT IDENTIFICAT ION
The PCI-COM422/485/2 port identities are shown in Figure 3-2 below:

Figure 3-2. PCI-COM422/485 Board Port Locations

3.3 CHANGING THE CO M PORT ASSIGNMENTS
In Windows 95/98, the PCI-COM ports is automatically installed, starting at COM5: (if available).
Alternatively, the next available port is assigned if COM5 is not available. Other ports on multi-port
boards are assigned in numeric sequence after the first port installed. If you wish to change the board’s
initial COM Port number (e.g. from COM5: to COM3), please follow the procedure below. Additional
ports on the board will also be changed so that the COM port assignments are sequential.
1. Right click on My Computer.
10

2. Click on Properties.
3. Click on the Device Manager tab.
4. Click on MultiFunction.
5. Click on PCI-COM.
6. Click on Resources
7. Uncheck the Automatic Settings box.
Note the I/O ranges listings. There will be one more range listed than the number of ports provided onyour board (e.g. the two port board will have three ranges listed). The first range +/-10 is a sharedinterrupt status register and should not be changed. Subsequent ranges are the actual COM port addresses.
Change the first port on your board to COM3: by following the procedure below:
1. Double click on the second I/O range listed. Highlight the complete listing.
2. Type; 03e8-03ef and click OK.
3. Windows will then notify you that you have made changes that may affect other devices.
4. Click OK.
If installing a multi-port board, you will want to install the board’s second port as COM4:. To do this:
1. Double click on the third I/O range.
2. Highlight the complete listing, then type 02e8-02ef and click OK.
3. Once again, windows will alert you that you have made modifications that may affect other devices.
4. Click OK.
Your COM ports have now been moved to COM3: and COM4:. If you are installing the four port board,ports 3 and 4 now reside at COM5: and COM6: respectively.
This sequence is not required under Windows NT as the PCI-COM422/485 ports will be installed as thenext available ports under NT. By default, a two-port PCI-COM422/485 board is installed as COM3: andCOM4:.

3.4 STANDARD COM PO RT CONFIGURATIONS
Table 3-1 lists the standard configurations for PC serial ports. Typically, COM1 and COM2 are assigned
to the on-board serial ports.
Table 3-1. PC Serial Port Standard Configurations
Port Name
COM1
COM2
COM3
COM4

Address Range
0x3F8 – 0x3FF
0x2F8 – 0x2FF
0x3E8 – 0x3EF
0x2E8 – 0x2EF

Interrupt
43
4
3

3.5 TERMINATION JUM PER SETTINGSThe PCI-COM422/485 board contains several jumpers that can be used to terminate a network.
Termination is used to match the impedance of the node with the impedance of the transmission line
being used. The use of termination techniques is very application-specific and beyond the scope of thisdocument. However, the PCI-COM422/485 does offer several termination configurations to help meet
individual application requirements. Termination resistors (120 Ohm) can be applied by moving therespective jumper from the DISABLE to the ENABLE position. (Information on RS422/485 termination
can be found in the B&B Electronics “RS-422 and RS-485 Application Note”, www.bb-elec.com.)11

4. REGISTER MAP
Although most users will take advantage of the COM driver supplied with the PCI-COM422/485 boards, thefollowing register map (Table 4-1) has information for users that may require it.

4.1 REGISTER MAP OVE RVIEW
Table 4-1. Register Map
REGISTERBADR1+4Ch

READ FUNCTION
Interrupt Status

WRITE FUNCTION
Interrupt Control

Operations
32-bitDWORD

BADR2 + 0
BADR2 + 1
BADR2 + 2
BADR2 + 3
BADR2 + 4
BADR2 + 5
BADR2 + 6
BADR2 + 7

Port 1 UARTPort 1 UARTPort 1 UARTPort 1 UARTPort 1 UARTPort 1 UARTPort 1 UARTPort 1 Clock Sel Register

Port 1 UARTPort 1 UARTPort 1 UARTPort 1 UARTPort 1 UARTPort 1 UARTPort 1 UART
Interrupt Status Register

8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTEBADR3 + 0
BADR3 + 1
BADR3 + 2
BADR3 + 3
BADR3 + 4
BADR3 + 5
BADR3 + 6
BADR3 + 7

Port 2 UARTPort 2 UARTPort 2 UARTPort 2 UARTPort 2 UARTPort 2 UARTPort 2 UARTPort 2 Clock Sel Register

Port 2 UARTPort 2 UARTPort 2 UARTPort 2 UARTPort 2 UARTPort 2 UARTPort 2 UART
Interrupt Status Register

8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE
8-bit BYTE

The single port PCI-COM422/485 board uses only Address range 1 and 2. The PCI-COM422/485/2 uses
Address range 1, 2 and 3.

4.2 REGISTER DESCRIP TIONS
4.2.1 INTERRUPT STATUS/CO NTROLBADR1 + 4C hex
This register, and all 9052 registers, is 32 bits long. Since the remainder of the register has specificcontrol functions, they would need to be masked off in order to access the interrupt control functions:
INTE is the Interrupt Enable:
0 = disabled, 1 = enabled (default).
INTPOL is the Interrupt Polarity:
0 = active low (default), 1 = active high.
INT is the Interrupt Status:
0 = interrupt is not active, 1 = interrupt is active.

12

31:8
x

7
x

6
x

READ/WRITE
4
3
X
x

5
x

2
INT

1
INTPOL0INTE

The UART ports are 16C550 compatible. See any 16C550 data sheet for register functions.
AVAILABLE PORTS:
PCI-COM422/485:
PORT 1
PCI-COM422/485-2:
PORTS 1-2
4.2.2 PORT 1 CLOCK SELECT / INTERRUPT STATUS
BADR2 + 07 hex

7
PORT1
TXSEL16PORT1TXSEL05PORT1CKSEL14PORT1CKSEL0

7

6

5

4

PORT1
TXSEL1PORT1TXSEL0PORT1CKSEL1PORT1CKSEL0

INTx

READ
3
-

2
-

1
INT2

0
INT1

WRITE
3

2

1

0

-

-

-

PORT1
ECHOENInterrupt status for each port. The same signals are connected to this read register for all ports.

CKSEL1:0

UART clock select. This allows for data rates to 460.8 Kbps and different data rates oneach port. These settings are per port:
CKSEL1
0
0
1

UART CLOCK
1.8432 MHz
3.6864 MHz
7.3728 MHz

CKSEL00
1
0

Max Data Rate
115.2 kbps
230.4 kbps
460.8 kbps

TXSEL1:0 Transmit data control select. This allows for controlling the Transmit Data driver. The
default mode for RS485 is ‘Auto Enable’. This mode is recommended for all RS485 communication.
TXSEL1TXSEL0
0
0
1

1

0
1
0
1

Transmit Control
Duplex Mode
Auto Enable
Half
RTS Enable
Half
DTR Enable
Half
Transmit ‘ON’
Full – RS422 Mode

ECHOEN 1:0 Echo enable/disable. When set low, this enables the hardware to echo the transmitted data to thereceiver. When set high, this disables the ‘Receiver Enable’ control signal on the RS485 transceiver while data is
being transmitted. Therefore, the transmitted data are not echoed to the receiver.
For TXSEL0:1 = ‘11’, ECHOEN has no function since this is full duplex mode and the transmitter and receiver arealways ‘ON’.

4.2.3 PORT 2 CLOCK SELECT / INTERRUPT STATUS
BADR3 + 07 hex

13

7
PORT2
TXSEL16PORT2TXSEL05
PORT2CKSEL14PORT2CKSEL07
PORT2
TXSEL16PORT2TXSEL05
PORT2CKSEL14PORT2CKSEL0

READ
3
-

WRITE
3
PORT2
ECHOEN

2
-

1
INT2

0
INT1

2
-

1
-

0
-

INTx
Interrupt status for each port. The same signals are connected to this read register for all ports.
CKSEL1:0
UART clock select. This allows for data rates to 460.8 Kbps and different data rates oneach port. These settings are per-port:
CKSEL1
0
0
1

UART CLOCK
1.8432 MHz
3.6864 MHz
7.3728 MHz

CKSEL00
1
0

Max Data Rate
115.2 kbps
230.4 kbps
460.8 kbps

TXSEL1:0 Transmit data control select. This allows for controlling the Transmit Data driver. The default
mode for RS485 is ‘Auto Enable’. This mode is recommended for all RS485 communication.
TXSEL1TXSEL0
0
0
1

1

0
1
0
1

Transmit Control
Duplex Mode
Auto Enable
Half
RTS Enable
Half
DTR Enable
Half
Transmit ‘ON’
Full – RS422 Mode

ECHOEN 1:0 Echo enable/disable. When set low, this enables the hardware to echo the transmitted data to thereceiver. When set high, this disables the ‘Receiver Enable’ control signal on the RS485 transceiver while data is
being transmitted. Therefore, the transmitted data are not echoed to the receiver.
For TXSEL0:1 = ‘11’, ECHOEN has no function since this is full duplex mode and the transmitter and receiver arealways ‘ON’.

14

5. SPECIFICATIONS
Typical for 25°C unless otherwise specified.
POWER CONSUMPTION+5V
PCI-COM422/485
PCI-COM422/485-2

240mA typ.
250mA typ.

COMMUNICATIONS SECTION
Number of Ports
PCI-COM422/485
PCI-COM422/485-2
Port TypeUART

1
2
RS422 or RS485 (software selectable)
16C550

Data Rate

Up to 460 kbaud, software selectable

Miscellaneous

RS485 mode is software programmable for RTS Enable,
DTS Enable or Automatic Enable
DB9F female 9-pin D connector

INPUT/OUTPUT SECTION
Data Transceiver type
Data Rate

SP491
5Mbps min.

Data Transceiver Output Characteristics
Vol 0.4V max. (Iout= +4mA)
Voh
3.5V min. (Iout= -4.0mA)
Differential Output Voltage GND to Vcc (unloaded)
Short Circuit Current±250mA
Propagation Delay 30ns typ. (tplh/tphl)
Driver Enable to Output High40ns typ.
Driver Enable to Output Low
40ns typ.
Driver Disable Time to Low40ns typ.
Driver Disable Time to High40ns typ.
Data Transceiver Input Characteristics
Vil 0.8V max.
Vih 2.0V min.
Maximum Input Voltage±14V
Differential Threshold Voltage±0.2V
Input Current
1mA (Vin = 12V)
-0.8mA (Vin=-7V)
Propagation Delay 90ns typ. (tplh/tphl)
Receiver Enable to Output Low
20ns typ.
Receiver Enable to Output High20ns typ.
Receiver Disable from Low 20ns typ.
Receiver Disable from High 20ns typ.

15

RTS/CTS Transceiver type
Data Rate

SP490
5Mbps min.

RTS/CTS Transceiver Input Characteristics
Input Voltage±14V max.
Data Rate 5Mbps min.
Differential Threshold Voltage±0.2V
Input Current
1mA (Vin = 12V)
-0.8mA (Vin=-7V)
Propagation Delay 90ns typ. (tplh/tphl)
RTS/CTS Transceiver Output Characteristics
Differential Output Voltage GND to Vcc (unloaded)
Short Circuit Current±250mA
Propagation Delay 30ns typ. (tplh/tphl)
Miscellaneous

All inputs supplied with 120 ohm jumper selectabletermination,
data pull-up and data pull-downresistors

TRANSIENT VOLTAGE SUPPRESION OPTION
Board Description
PCI-COM422/485/S
PCI-COM422/485-2/S
Data Transceiver Input

RTS/CTS Transceiver Input

TVS type
Working Voltage
Breakdown Voltage
14.7V max.
Peak Pulse Surge Current
Peak Pulse Power Dissipation

ENVIRONMENTAL
Operating temperature range
Storage temperature range
Humidity

SP491
Input Voltage Range (derated)

±12V

SP490
Input Voltage Range (derated)±12V

SMAJ12A±12V
13.3V min.
15.1A max. (avalanche duration time =10µs)
300W max. (avalanche duration time =10µs)
Peak Pulse Power Dissipation is proportional to theamount of time the TVS remains in the avalanche
mode. For specific power vs. avalanche duration
information, consult the SMAJ12A datasheet.

0 to 70°C-40 to 100°C
0 to 90% non-condensing

16

6. TROUBLESHOOTING Q/A:
1) The system was working before I rebooted and now no longer works.
The main issue with detecting the PCI-COM hardware involves the system-assigned base address. The PCICOM board relies on the Plug-and-Play capabilities of the system BIOS to assign the base address for the COM
ports. When new hardware is added to the machine, the entire system is reconfigured. This might affect theaddresses assigned to the PCI-COM board and hence where the system detects the board. The easiest way todeal with this issue is to go into the Device Manager and delete the “PCI-COM…” entry under the “MultiFunction” node and reboot the system. This will force the system to reconfigure the PCI-COM board. After themachine has rebooted, go back into the Ports entry under the Device Manager and configure the Advanced
settings. This forces the system to write the new settings to the registry. If you installed the ComSet32.exe
application in the Startup folder, the new configuration is restored after each reboot.
2) I cannot configure an internal modem under Windows NT.
The PCI-COM installation replaces the standard Windows NT Serial.sys device driver with a modified driverthat supports the PCI-COM family of boards. The modified driver will work for any of the boards in the PCICOM family as well as the internal COM1 and COM2 ports. However, there is an issue with the system being
able to detect internal modems. This appears to be a resource-related issue with the current implementation of
the modified serial device driver. Until this issue is resolved, internal modems are not supported on machineswith PCI-COM boards.

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EC Declaration of Conformity
We, ComputerBoards, Inc., declare under sole responsibility that the product:
PCI-COM422/485 seriesPart Number

RS-422/485 interface for the PCI
bus
Description

to which this declaration relates, meets the essential requirements, is in conformity with, and CE marking
has been applied according to the relevant EC Directives listed below using the relevant section of thefollowing EC standards and other informative documents:
EU EMC Directive 89/336/EEC: Essential requirements relating to electromagnetic compatibility.
EU 55022 Class B: Limits and methods of measurements of radio interference characteristics ofinformation technology equipment.
EN 50082-1: EC generic immunity requirements.
IEC 801-2: Electrostatic discharge requirements for industrial process measurement and control
equipment.
IEC 801-3: Radiated electromagnetic field requirements for industrial process measurements and control
equipment.
IEC 801-4: Electrically fast transients for industrial process measurement and control equipment.

Carl Haapaoja, Director of Quality Assurance

19ComputerBoards, Inc.
16 Commerce Blvd.,
Middleboro, MA 02346
Tel: (508) 946-5100
Fax: (508) 946-9500
Web: www.computerboards.com