cportlib
I have tried a few, but the main problem was, that the most of them uses the VCL library. Since I am developing cross platform applications I am using the CLX library.
The only CLX comport component that I have found (and which is still have support) is the nrComm library:
**broken link removed**
This is not free, I had to pay for it, but have good support. (When I have found a bug in it, they repaired it in two days.)
I really don't understand Borland, why they have not included such a basic thing in their developement tool...