Copyright: Copyright ©1999


BERT Page
BERT (Bit Error Rate Test) Page

Overview

The Bit Error Rate Test (BERT) sends a binary pattern that cycles through every possible bit sequence.  It tests any received data against that pattern, keeping track of the number of sync losses and bit errors.  The test can be set up on one port using a "loopback" conector, or on two ports connected by a null modem.

Technical Info

The test pattern is a cyclic binary sequence intended to emulate white noise on a serial connection.  It is produced by repeatedly shifting a byte using the following polynomial:

1 + x^4 + x^9.

Caution

In order for the BERT test to function, the port must be set to 8 data bits.  Also, since the test uses a cyclic binary pattern, enabling XOn/XOff flow control will cause the test to not work correctly.  To change these settings, go to the Port Information tab and click on the Settings button.

Layout

Click on the picture below to get more specific information.


BERT::Bit Errors
The number of bit errors detected in the bytes checked.


BERT::Bytes Checked
The number of bytes that have been received and successfuly checked against the pattern.


BERT::Reset Button
Resets all the statistics to 0.


BERT::Rx Data Rate
The receive data rate in bits per second.  This number is only an estimate, updated every couple seconds, and does not provide accurate or instantaneous rate information.  Furthermore, the data bits, start, stop, and parity bits are included.  (This is a change from previous versions of WinSSD.)

Also, if the input is "out of sync," this number will be 0.


BERT::Rx Frames
Number of frames received.  Each frame consists of a binary string 511 bytes long.


BERT::Start Button
Starts the BERT test by transmitting the binary pattern.

Once the test is started, this button changes to Stop.  Click here to stop transmitting.


BERT::Sync Losses
The number of times that the pattern has fallen out of sync.  WinSSD searches for the pattern in the incoming data, and keeps a count of the number of times it "loses track."


BERT::Sync Status
The status of the received signal.  There are four possibilities:

No Data

Out of Sync	(red light)

Searching	(yellow light)

In Sync	(green light).


BERT::Test Time
The time elapsed since the start of the BERT test.  Since WinSSD is constantly monitoring the receive line, the test starts when the user clicks on the BERT page.


BERT::Tx Data Rate
The trasmit data rate in bits per second.  This number is only an estimate, updated every couple seconds, and does not provide accurate or instantaneous rate information.  Furthermore, the data bits, start, stop, and parity bits are included.  (This is a change from previous versions of WinSSD.)


BERT::Tx Frames
Number of frames transmitted.  Each frame consists of a binary string 511 bytes long.


DB25 RS232


DB25 RS422


DB25 RS530


DB9 RS232


DB9 RS422


Loopback Connector

In order to build a loopback connector, use the diagram appropriate for your adapter.

DB9 RS-232

DB9 RS-422

DB25 RS-232

DB25 RS-422

DB25 RS-530


Loopback Page

Overview

The loopback page allows the user to test a single port by sending patterns and comparing them to the data received.  It is necessary to have a "loopback" installed on the port connector in order for the port to be able to receive its own transmited data.

Caution

Make sure that a "loopback" is installed on the correct port connector.  If not, the test will either timeout or freeze, depending on the timeout values.  If the test freezes, hit the cancel button.

Do not try to run the loopback test on two ports connected by a null modem.  The test will not run properly, since it was designed to test a single port with a "loopback."

Layout

Click on the picture below to get more specific information.


Loopback::ASCII Check Box
Click here to enable or disable the "ASCII message" loopback test.


Loopback::ASCII Test
ASCII Test

Repeatedly sends the following sentence:

The quick brown fox jumped over the lazy dog's back.


Loopback::Counters
Number of times the test has been repeated.  For example:

19 / 20

The first number indicates that the pattern, sentence, or modem control signal has been sent (or raised, in the case of the control signals) 19 times.  The second number indicates that it should have been sent/raised 20 times.  The second number can be changed, allowing the user to repeat the test as many times as desired.


Loopback::Diagrams Button
Brings up a window illustrating the electrical connections for each type of loopback, allowing the user to create a connector.


Loopback::Modem Check Box
Click here to enable or disable the "Modem Control Signals" loopback test.


Loopback::Modem Test
Modem Control Test

Repeatedly raises and lowers the RTS and DTR modem control signals while checking the status of CTS, DSR, RI, and DCD.


Loopback::Pattern Check Box
Click here to enable or disable the "Pattern" loopback test.


Loopback::Pattern Test
Pattern Test

Repeatedly sends a pattern.  The pattern (55AA in 8 bit mode) is an alternating sequence of 1's and 0's.  For a more extensive pattern loopback test, set up the Bit Error Rate Test (BERT) using a "loopback" connector.  The BERT test sends a binary pattern that cycles through every possible bit sequence.


Loopback::Progress Bar
Indicates the overall progress of the test, giving an estimate of the time left until the test is finished.


Loopback::Start Button
Before the test is started, this is the Start button.  Click here to start the test.  Make sure to select the desired tests by clicking on the apropriate check boxes before the test is started.

Once the test is started, this button changes to Cancel.  Click here to cancel a test in progress.


Port Information Page

Overview

The port information page serves two purposes.  It allows the user to open and configure the port, and it also displays a log of errors reported by the serial driver.

Caution

WinSSD is designed to give maximum control to the user.  Because of this, not all settings will work optimally.  Be especially careful when changing the timeouts, since this can drastically change the behavior of the tests.

Some combinations of settings will cause certain tests to perform incorrectly.  For example, setting the byte length to 6 data bits will cause the ASCII loopback test to not function.  Also refer to the Caution on the help page for the BERT test.

Timeouts

the timeout values are in milliseconds.  The default settings (100ms) provide good performance at most speeds.  If problems are encountered are really slow speeds, increase the timeout values.

In order to disable the timeouts (ie: set the timeout to infinite), set all the values to 0.

Layout

Click on the picture below to get more specific information.


Port Information::Com Port
Enter the desired comm port number here.


Port Information::Error Count
The error log keeps a running count of the following errors:

Frame Errors

Parity Errors

Receive Buffer Overflow Errors

Transmit Buffer Overflow Errors

The values indicate the total number of errors of that type having occured during the current WinSSD session.


Port Information::Error Log
The error log keeps track of most errors reported by the serial driver.  The errors are kept in a list, using the following format:

<Time Stamp> : <Error Description>


Port Information::Open Button
Click here to open the currently selected comm port.  If the port does not exist, or if there is a problem opening the port, WinSSD will return an error message.

Once the port is open, this button becomes the Close button.  Click on it to close the currently open comm port.


Port Information::RITimeout
Read Interval Timout:

Sets the maximum time (in milliseconds) allowed to elapsed between each received character on the serial port.  If that time is exceeded, the serial driver will report a timeout.


Port Information::RTTimeoutC
Read Total Timeout Constant:

Sets the constant (in milliseconds) for the receive timeout.  This value indicates the minimum amount of time that a read operation should wait before reporting a timeout.  It is used in combination with the Read Total Timeout Multiplier to calculate the final receive timeout.


Port Information::RTTimeoutM
Read Total timeout Multiplier:

Sets the multiplier (in milli seconds) for the receive timeout.  When performing read operations, this value is multiplied by the number of bytes to be read, and then added to the Read Total Timeout Constant, producing the final receive timeout.


Port Information::Settings Button
Click here to open the settings dialog.  This is were all the basic configuration options are changed (baud rate, data bits, flow control...).

WARNING: some combinations of settings will cause certain tests to perform incorrectly (Such as 6 data bits when doing a loopback ASCII test.  Also refer to the Caution on the help page for the BERT test).


Port Information::WTTimeoutC
Write Total Timeout Constant:

Sets the constant (in milliseconds) for the transmit  timeout.  This value indicates the minimum amount of time that a write operation should wait before reporting a timeout.  It is used in combination with the Write Total Timeout Multiplier to calculate the final transmit timeout.


Port Information::WTTimeoutM
Write Total timeout Multiplier:

Sets the multiplier (in milli seconds) for the transmit timeout.  When performing write operations, this value is multiplied by the number of bytes to be written, and then added to the Write Total Timeout Constant, producing the final transmit timeout.


Terminal Page

Overview

The terminal emulation page consists of a console providing simple ASCII dumb-terminal emulation.  Any characters typed will be sent directly to the open port, while any received characters will be displayed in the window.

Layout

Click on the picture below to get more specific information.


Terminal::Hex Mode
Click here to enable/disable Hex Display Mode.  When this is enabled, all bytes received are displayed as a hexadecimal value, instead of using their ASCII equivalent.


Terminal::Local Echo
Click here to enable/disable Local Echo Mode.  When this is enabled, any characters transmitted will also be echoed to the display.


Terminal::Main Window
This is where all received data is displayed (as well as all typed characters, if the Local Echo option is enabled).


WinSSD Overview
WinSSD 2.01

Windows System Serial Diagnostics

Version 2.5.26

Description

WinSSD is a tool used to test serial ports, as well as the quality of the connection between two different ports.  It provides maximum flexibility to the user, allowing them to modify a number of operating parameters, such as timeouts and flow control.  Because of this, it is useful in many situations, both for the end user and for the software/driver developer.

Platforms

• Win95 / 98 / NT / 2000

Functional Overview

• Advanced parameter control (timeouts, ...)

• Error log

• Customizable loopback test (including modem control signals)

• Bit Error Rate Test (BERT)

• ASCII/Hex simple terminal emulation

• Modem control bits show / toggle

Quick Start

• Attach a loopback connecter to the serial port in question

• Open WinSSD by double clicking on the program icon

• Select the COM number for the desired serial port (the one with the loopback connector)

• Click the "Open" button

• Select one of the other program tabs (Loopback, BERT, Terminal) and start the desired test

Layout

The WinSSD main window consists of a tab control containing four control pages and a panel which manipulates and displays the modem control bits.

Modem Control Panel

WinSSD incorporates some functionality to display and modify the modem input and output bits.  The displayed input bits are: CTS (clear to send), DSR (data set ready), RI (ring indicator) and DCD (carrier detect).  These lights will flash green when set.  The modifiable output bits, which flash yellow when set, are: RTS (request to send) and DTR (data terminal ready).  Click the buttons next to these two lights to toggle their current status.  Note that the output lights are intended to display the current bit status in software only, and are not actually read from the hardware itself!  This means that under certain settings (i.e. if the hardware automatically controls the flow bits), these lights may be inaccurate and the toggle buttons nonfunctional.  If hardware flow control is specified within WinSSD, the output toggle buttons will be disabled.

Control Pages

Click on the links for information about each page:

• Port Information

• Loopback

• BERT (Bit Error Rate Test)

• Terminal