Have bben working with a Plam application that read data from a device connected on the serial port. Had some problems with it. To see what actually was received I needed some tools and I found these;

RealTerm from SourceForge. Its specifically developed for debugging serial communication!

HCalc was also convinient to have when calculating CRCs.

The RealTerm people are working on another project I should check out when I got time. A PIC programmer, called PP06.