c# - Monitor a COM port already in use -

Is it already used on a Windows XP port from a port?

I would like to see the communication between some software and a device that was plugged into a serial device. I wrote a small program using C # to monitor COM, but once it is used by another device it will not let you open it again. How to monitor a COM port in advance Could?

I am open to third-party software.

Yes, it is technically possible that you will need a filter driver, one device of one component Driver type that is already injected with the original serial port driver. The driver gets a crack on the IRPs before sending them to the regular driver.

This technique is used by the SysInternals PortMon utility, however, you can not write such a driver in the C # code, CLR can not be loaded in ring 0. At least as long as the Super-Secret Midori project does not see the light of day.

COM filter drives are very common, for example check out though you have to score a few goals to detect a NAT cover.