Error 8020

I have a program I wrote in VB 6 and it has been used on XP machines. Now someone is installing it on a Vista machine. We are using a TRENDNET TU-S9 USB - Serial adapter. I download the newest Vista/XP drivers. It show up as a Prolific USB - Serial adapter. This is the same USB - Serial adapter we have used on XP machines. I installed the same driver on my XP machine and it works fine.
So is it a Driver issue or a Vista Issue? From Microsoft http://support.microsoft.com/kb/318784
If it is a adapter issue anyone have one they use with Vista and MSComm

so the program you write on vb6 doesn't work with vista or what?

The program runs fine until it trys to acess the Com port. Then it gives error 8020. This only happens in Vista 64 (so far) using the same USB to Serial adapter I used in the past and tested again with XP.

I would say start by checking the COM number assigned to your USB-RS232 device in the control panel. Verify that your application is indeed opening up the correct COM port.

If everything is as expected, I would open hyperterminal and verify you are receiving data from the USB-RS232 device when expected.

As a last resort, you can download portmon and "sniff" the RS232 line as well as see some other information...
PortMon

This is in vista
I know what port number is assigned to the USB to Serial adapter. I checked in control panel. (Com for for the test)
Everything see the comport it is just when I open it I get the problem.
Im not sure using another program would be any help other than telling me that the com port works that that program.
From http://support.microsoft.com/kb/318784

Quote:

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When you use the Input method of the MSComm control with some serial ports, the MSComm.Input method may fail, and you may receive the comReadError error (error 8020).

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and

Quote:

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This problem is only known to occur with some third-party serial drivers. To correct the problem, contact the manufacturer of the serial driver to obtain an updated driver.

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So unless the other program is using MSComm it most likely will work.

Again this only happens in Vista It has never happened in XP Pro or Home.

it may be as much a 64 bit problem, did you try with XP64?

try to use this software to debug your issue...

USBlyzer - Professional Software USB Protocol Analyzer

or

http://www.aggsoft.com/serial-port-m...2-analyzer.htm