10623 Roselle Street, San Diego, CA 92121
TEL (858)550-9559 FAX (858)550-7322
MODEL PCI-COM422/4
USER MANUAL
FILE: MPCICOM422-4.E1b
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 1995 by ACCES I/O Products Inc, 10623 Roselle Street, San Diego, CA 92121.
All rights reserved.
Page iii
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.
The PCI-COM422/4 Serial Interface Card was designed for effective transmission in RS422 (EIA422)
protocol. The card is 6.1 inches long and may be installed in PCI-bus slots of IBM PC or compatible
computers. The card features four independent, asynchronous RS422 serial ports, type 16550
buffered UARTs, and, for Windows compatibility, automatic control to transparently enable/disable
the transmission drivers.
There are two I/O connector options. The standard model PCI-COM422/4 includes a single DB25
male connector on the mounting bracket plus a breakout cable that terminates in four 9-pin female
connectors. Optional model PCI-COM422/4S1 has two 9-pin male connectors on the card mounting
bracket plus a second mounting bracket with two more 9-pin male connectors with ribbon cables to
connect them to headers on the card.
RS422 Balanced Mode Operation
The PCI-COM422/4 supports RS422 communications and uses differential balanced drivers for long
range and noise immunity. PCI-COM422/4 also has the capability to add load resistors to terminate
the communications lines. RS422 communications requires that a transmitter supply a bias voltage
to ensure a known "zero" state. Also, receiver inputs at each end of the network should be terminated
to eliminate "ringing". The PCI-COM422/4 supports biasing by default and supports termination by
jumpers on the card. If your application requires the transmitter to be un-biased, please contact the
factory.
COM Port Compatibility
Type 16550 UARTs are used as the Asynchronous Communication Element (ACE). These include
a 16-byte transmit/receive buffer to protect against lost data in multitasking operating systems, while
maintaining 100 percent compatibility with the original IBM serial port. The system assigns the
address(es).
A crystal oscillator is located on the card. This oscillator ensures precise selection of baud rates up
to 115,200 or, by changing a jumper, up to 460,800 with the standard crystal oscillator.
The driver/receiver used, the SN75176B, 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.
Communication Mode
PCI-COM422/4 supports Full-Duplex and Half-Duplex communications with a 4-wire cable
connection. Half-Duplex allows traffic to travel in both directions, but only one way at a time.
Manual MPCICOM422-4.E1b
Page 1-1
PCI-COM422/4 Manual
Baud Rate Ranges
The card has capability for two baud rate ranges and you can select which you wish to use on a
port-by-port basis. One range is for up to 115,200 baud applications and the other is up to 460,800
baud applications.
Specifications
Communications Interface
•I/O Connection:9-pin D-sub connectors
•Serial Ports:Four shielded male D-sub 9-pin IBM AT style connectors
compatible with RS422 specifications. (Note: On model an
external "spider" or breakout cable terminates with four female
D-sub 9-pin connectors.)
•Character length:5, 6, 7, or 8 bits.
•Parity:Even, odd or none.
•Stop Interval:1, 1.5, or 2 bits.
•Serial Data Rates:Up to 115,200 baud, Asynchronous, A faster range of rates up
to 460,800, is achieved by jumper selection on the card. Type
16550 buffered UART.
•Address:Continuously mappable within 0000 to FFFF (hex) range of PCI
bus addresses (Conforms to PCI Specification 2.1).