I am using a USB Serial Port Adapter on several different computers all of which run Windows XP home or Windows XP Pro. I installed the USB Serial Port Adapter using the XP drivers supplied by manufacturer on each computer. The USB Serial Adapter installed and setup fine. In device manager all looked good. But some of the USB Serial ports did not seem to pass data through them correctly or the peripheral could not communicate with the program. Opening HyperTerminal I was able to connect on some of the computers and some I could not make a connection through the USB Serial Port Adapter. Some passed data to HyperTerminal without a problem but some “dropped” parts of the data passing through. After doing a lot of trouble shooting I finally narrowed it down to 2 specific Open Host Controllers that were causing the problem. If the computer had an Intel or NEC or Standard Open Host Controller I had no problem with any peripheral I would connect to the USB serial port adapter. The peripherals could communicate with any appropriate program running in the Windows XP operating system. If the Open Host Controller was an ALI or VIA Rev 5 or later I would have problems. These two Open Host Controllers would cause the peripheral notto connect to the program/programs running in the Windows XP OS or I would have data bytes dropped.
What would be the cause of this behavior? The same USB serial port adapter, the same peripheral and the same program would work perfectly on a desktop or laptop with Windows XP Home or Windows XP Pro if the Open Host Controller was Intel, NEC, or listed as Standard but would not work if the Open Host Controller was an ALI or VIA Rev 5 or later. If I removed Windows XP and loaded W98 or Windows ME everything worked with all Open Host Controller! Is it the driver, Win XP, open host controller or a combination of some or all?