Serial write blocks

Rob

Hi,
I am developing an application that does constant serial communication.
The application is closely guarded for looptimes and hanging threads.
I noticed that my commu-thread ofter hangs, or reports long looptimes.

This thread writes to the comport.
All Write timeouts are set to 0 (not used).
Another thread is continuously reading from the port.
This can be done at the same time right ? (read/write I mean).
I know enough about uarts to know they can do it, but I don't know if the
win32 api has it's own idea's about this. (note that actually I'm using a
virtual USB comport).

I am using regular WriteFile()/Readfile(), and SetCommTimeouts().
What could be the problem with the long write times ? (or even hangups)
Maybe the virtual comport driver is to blame ?
I never saw this behaviour on regular comports.

Greetings,
Rob.