Lucent Technologies PassageWay Service Provider For PARTNER Communications System Getting Started

Troubleshooting
4-22
Failure Code -121
Meaning: The PC and the PassageWay adapter cannot communicate
over your serial port.
Things to Try: Follow the instructions for Failure Code 111.
Failure Code -131, -132, -133, or -135
Meaning: The PC cannot communicate properly with your PassageWay
adapter.
Things to Try: Try replacing any RS-232 cables or adapters you are using
between your PC’s COM port and the PassageWay adapter’s 25-pin
connector.
Failure Code -134 or -141
Meaning: The PassageWay adapter cannot...

Troubleshooting
4-23
Problem 3: Connect will not work on COM ports other than COM1 and
COM2.
By default, many PCs are not configured to permit the simultaneous use of
three or more COM ports. Specifically, most PCs are configured such that
COM ports are grouped into pairs: COM1 is paired with COM3, and COM2 is
paired with COM4. By default, such PCs permit only one COM port from each
pair to be operating at the same time (for example, COM1 with COM2). COM
ports within the same pair will usually conflict...

Troubleshooting
4-24
The chance of a communications problem depends on your PCs
configuration. The PassageWay Service Provider operates at a data rate of
4800 baud, and it relies on Windows to manage the flow of data through your
PCs serial port. Depending upon the speed of your PC, the number and type
of applications you are using, and various hardware components in your PC
configuration, Windows will be able to manage serial communications with
varying degrees of effectiveness.
If you encounter...

PC Serial Ports
A
A-1
Overview
This appendix provides detailed information about PC serial ports, including
background information about what they are and how they work.  It also
explains how Microsoft Windows 3.1 manages serial ports, how to resolve
problems using COM3 or COM4 under Windows, and how to choose serial
port hardware that is well-suited to the PassageWay Service Provider.  If you
are familiar with serial port terminology (for example, I/O port addresses,
IRQs, etc.), you may wish to skip...

PC Serial Ports
A-2
Background
Serial ports (also sometimes referred to as communications ports or COM
ports) are hardware interfaces that permit your PCs microprocessor to
communicate with peripheral devices using a communications standard
called RS-232 (hence, serial ports are also sometimes referred to as RS-232
ports).  Many common computer accessories make use of serial ports,
including serial mice, modems, and serial printers.
Under DOS (and Windows, which works cooperatively with DOS), the serial...

PC Serial Ports
A-3
The microprocessor/serial port communication consists of two aspects:  an
I/O port address and an interrupt request signal (IRQ).  The I/O port address
represents a small region of the microprocessors input/output memory space
that is used to pass data back and forth to the serial port.  This memory
region acts something like a mailbox:  Outgoing mail (data from the
microprocessor to be transmitted to the peripheral device) is placed in the
mailbox by the owner (the microprocessor) to...

PC Serial Ports
A-4
In the PC architecture, IRQs acts like the doorbell in our analogy:  They
provide a method by which hardware devices in the computer can get the
microprocessors attention to deal efficiently with some process.  The serial
port hardware makes use of an IRQ to announce that it is ready to receive
more outgoing data and/or that new data have arrived from the peripheral
device that need to be processed.
Like I/O port addresses, IRQs must generally be unique among the active
hardware...

PC Serial Ports
A-5
The table below lists the default I/O port addresses and IRQs used by the
serial ports of IBM-PC/AT-compatible computers:
Serial Port
Device NameI/O Port Address IRQ
COM1 03F8 4
COM2 02F8 3
COM3 03E8 4
COM4 02E8 3
The values in this table play an important part in understanding the “wrinkles”
associated with serial ports:  although there is provision for up to four serial
ports, with four unique I/O addresses, there are only two unique IRQs
associated with them (recall that most PCs...

PC Serial Ports
A-6 Serial Ports Under Windows 3.1
Unlike the DOS-only world of yesterday, todays multitasking environments
like Windows permit the microprocessor to communicate with up to four active
serial port devices at the same time (COM1 through COM4).  For example,
under Windows, if you are using a serial mouse (on COM1) within a terminal
emulator program that operates a data modem (on COM2), while using a fax
board (on COM3) to transmit or receive a fax “in the background,” you are
using three...

PC Serial Ports
A-7
Workarounds and Solutions to the
IRQ Conflict Problem
It is important to remember that the IRQ conflict is a problem in hardware; it
cannot be resolved in software alone.  Consequently, there are only three
alternatives for working around or resolving it:
Workaround 1:  Configure your serial devices such that you use only
two at any one time, and those two use serial ports with unique IRQs.
This is the simplest workaround to the IRQ conflict problem, but it does not
solve the...