I have been developing applications professionally for over 16 years in multiple industries.
My suggestion for this application would be to develop it as a C++ application using the Qt framework ([login to view URL]). This framework has classes specifically for serial port handling. I just completed a similar project for a client pulling GPS data over a serial link using Qt on Linux. Another benefit of going this route (Qt) is that it makes the application more portable (can be recompiled for windows/linux).
This seems to be a very straight forward project. It would be nice to have a more extensive data log from the device (can be generated by hooking up to the serial port with Putty or another terminal program). Additional data provides the developer a better chance of creating parsing routines that cover all cases.
I will be honest, I have not distributed a Qt application for Mac, I have only distributed windows/linux Qt applications, but I'm sure this is achievable.
I operate a small software firm in the Dallas, Texas, USA Metroplex area ([login to view URL]), you would be dealing with someone who speaks English natively and has excellent communication skills.
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If you look at my freelancer profile, you will see that while I am a fairly new freelancer, I have excellent reviews and repeat customers.
Thank you for the opportunity to bid on this project.