CreateTwinPort Method

Creates virtual serial port twin with non-standard name.


Visual Basic .NET
Sub CreateTwinPort(ByVal PortName As String, ByVal Alias As String) 
Visual C#
void CreateTwinPort(String PortName, String Alias);



[in] The name of virtual serial port (e.g. "COM1", "VSP25", "SERPORT10" etc). Names "COM0", "COM4294967295" and "LPTx" are prohibited.


[in] Alias name for existing COM port. You still will be able to open existing COM port using this alias name. The string is an MS-DOS path (e.g. PORT1, COM100).


TRUE - the port has been created successfully, FALSE otherwise.


The method may throw exception. Use GetLastError method to get the error code.

ftvspcErrorFailed 1 The operation has not been completed.
ftvspcErrorInvalidParameter 2 Invalid parameter.
ftvspcErrorPortAlreadyExists 100 This port already exists.


Port twin is an overlapped virtual serial port created over the physical serial port and existent only when the physical port exists.

Once created, port twin is available for enumeration by EnumVirtual function but does not exist in the system (does not visible in the device manager). It appears in the system only if corresponding physical port appears. When physical port is removed from the system, port twin is removed too.

Port twin can be permanent. In this case it will be available for enumeration by EnumVirtual function at each system startup and will exist in the system if corresponding physical port exists.