jdegama

com ports I am using com ports in my C# windows applications, It is not the most elegant solution, but I use the mscomm control that comes with Visual Basic to send and receive data to instruments and PLC's using com 1 or com 2. jerry

Same Problem I think this exception is not a lot of help. I am writing in C# and when I try to send data out of Com1 and the port is already open I am receiving the same exact message. I would assume that either your Com4 does not exist or is alredy open. Maybe another member has a better idea.