Comm Port in VB.NET

Question

Hi friends,
I'm trying to write/read on a device on Comm Port (RS232) but it's not working properly.
VB.NET 2005,  is there somebody with a smiple example code to write a string on a port and read a returning string out of comm port input buffer (not byte after byte - it's to slow and dificult to synchronise with other events)
Thanks for any help.
Sandra