How to read from a serial port using xpcom from Firefox?

I want to use xpcom to connect Mozilla Firefox to a se开发者_如何学编程rial port. The final result should be an xpi addon that can be installed on various environments (cross-platform Windows/Linux with Firefox 3.*). Where should I start?

I have found an example here: http://forums.mozillazine.org/viewtopic.php?f=19&t=1083965&start=0 , but I think that code will only work on Linux... Can I do something similar in Windows?

XPCOM is not for serial port communication. From what I can see, it is any interface to MS COM.

Please research your questions a little.