I am writing a Python (2.6) app which is making use of com0com virtual serial ports. It is running on Windows Server 2008 R2 (sp1) (I am also seeing the same issue on my dev machine which is Win 7).
The com0com port pairs are created prior to the app running. The app opens the ports (by creating serial.Serial objects), makes use of them & then closes them.
Attempting to re-use that port too soon fails - calling the constructor is fine (that is, it returns an open serial.Serial object) but this object appears to be unusable. As these objects are being used by another application, it is possible that application is not releasing something correctly.
Is there a known interval I should be waiting to re-use the com0com ports? Could it be that the com0com ports are set up wrongly in some way? Or something else?
Pseudo-code super high level overview of code:
loop:
serialPort = serial.Serial(port=COM90)
subprocess.check_call([blah.exe, "COM90"])
# this check_call succeeds on first iteration
# fails on second iteration, but will succeed subsequently ...
serialPort.close()
# pause before reusing COM90