With Serial Port Monitor ActiveX you can:
Monitor already opened ports
Start monitoring the port that has already been opened by another application. Serial Port Monitor ActiveX will tell you which application exactly has opened the port. You can stop monitoring the port the same way, without the need to close the port first.
Monitor all serial port activity in your system
Serial Port Monitor ActiveX will let your application sniff all communication between application and serial port. Serial Port Monitor component features a complete set of methods, events and properties to let you intercept all data that has been sent to a port, any changes to port's settings and track everything that happens to the port.