Another USB-Serial problem, possible bug report

I suspect VMSPC (V24B2) does not work properly with COM ports above COM9. In an effort to get a more reliable connection to my Dell Inspiron 6000 laptop (XP Pro 2002 SP3) I have tried several USB to serial cables with PL-2303 and HL-340 chips. Depending on which of my USB ports I plug into, the COM port assigned range from 8 to 12 as noted in the Device Manager. When using 8 or 9 VMSPC recognizes the port (no port failure message) and displays engine data correctly. When using ports assigned to 10, 11 or 12 port failure is always reported. I know the double digit ports work because I plugged a RS-232 GPS into them and streets and trips 2009 recognized the GPS device and acquired data.


You are generally correct.

We don't know why - in theory there is no difference. But we often find it necessary to go into the Device Manager and force the COM port to a smaller number. In some cases Windows will give you a message telling you that this will have unpredictable results . . . but the results are that it works!