Table of Contents

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Introduction

Ever since computers were invented, the ability to communicate with them was paramount. The RS 232 serial port became the standard way to do this. Modern computers now use USB ports to communicate together be it a camera, mobile phone or a hard disk drive.

There are programs on the internet that test Serial Ports. The object of this section is to use these programs to test the different USB Serial cables that are candidates to use with Eazylink2.

64 bit

Software

The following windows software was downloaded.

File Name	Release Date	Version	File Size
PL2303_CableTest_v2.2.1.1.zip	2010/02/25	2.2.1.1	753.78KB
COM PORT STRESS TEST	March 11, 2014.	1.4.3 build 907.

Hardware

The following items were made

Name	Item	Circuit	Function
Loopback Connector			To test individual Serial Port
NULL MODEM adapter			To connect two Serial Ports together

Tested USB Serial Cables

Manufacture Chip set	PL2303HX PLUGABLE	Image Added CH340	FT232R TRONIX	FT232R CHIP-10X	TUSB3410
Picture		Image Added
Where Purchased
COM Port	4		3	6	5
8/6/14 inc. VAT £ p+p	£11.59		£9.98	£19.18	£23.99

Test & Results

Run as administrator
	It was found that unless these programs were "Run as administrator," errors and a Blue Screen Of Death were encountered.

PL-2303 - Cable Test Program Ver 2.2.1.1

This program tests two serial ports, by sending data from one port to the other, changing each parameter settings and reporting the result of each test.

This screen shot shows a successful test
provided the Check Signal Events
was un-ticked.

The RTS Signal testing ... section failed.
This was due to the cable was a 3 wire type.
This only connects the data pins together.

I now have a correctly wired NULL MODEM Cable. Here are the The results of 2 USB Serial Cable connected together with a NULL MODEM Cable shows they are all OK.

Both FTDI

Serial

cables

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,	Keyspan & Prolific

Serial cables

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Keyspan & FTDI

Serial cables

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Image Added	Image Added	Image Added

Com Port Stress Test

This program either tests COM Ports individually, or with 2 COM ports as above.

Dual USB Serial Cable Results

These results shows the test running at different baud rates with RTS and CTS enabled.

If the COM port is faulty, error messages are generated and recorded into a log file.

Both FTDI Serial cables

115200 baud

This is not using any handshaking and has no errors

This is using RTS & DTR and has no errors

38400 baud

This is using RTS & DTR and has no errors

9600 baud

This is using RTS & DTR and has no errors

Keyspan & Prolific Serial cables

38400 baud

This is using RTS and DTR, reports errors to start with and then is stable.

Keyspan & FTDI Serial cables

This is using RTS and DTR, reports errors to start with and then is stable.

Prolific & FTDI Serial cables

This is using RTS and DTR, reports errors to start with and then is stable.

Single USB Serial Cable Results

These results shows the test running at 38400 baud with RTS and CTS enabled. There are different values in the port settings. This had no effect on the speed of transfer.