I'm not sure this is the right category that I post this question.

I have BarCode generating application using MSComm control. This was originally written by BASIC and converted,newly made,with VFP5. The problem is this application works good on some machine but doesn't work on another. On such not-working machine, the pringting signal goes to LPT port instead Com port connected to Zebra Labler. It's the same using legacy BASIC program.

What can be the main reason of that problem ? I think it's not the application or Comm control but the configuration of those PCs. Is there anyone can tell us why ?

TIA