I’m using QuickBasic 3.0 to read a scanner on a serial port (Com1) using XP SP2. I recently added a shell out to DOS to run a Visual Basic program. I can scan a barcode fine, but now when I return after the shell to the XP DOS emulator, my com port gives me and error 68, “DEVICE UNAVAILABLE ERR 68”. What I can find says that SP2 closes the com port when not in use. I can scan multiple times without errors if I don’t SHELL to DOS.
I know this is old school stuff, but it’s what this old system uses.
Any suggestions as to how to fix this ?
