Hi kwads,
I have not used the Arlyn 6200 scale specifically, but I believe your best bet is going to be to use VISA programming. VISA allows for easy reading and writing to serial ports, and works with both RS-232 and RS-485. Here is a link to a Serial Quick Reference Guide which gives some basics about serial communication, and shows a basic program that uses VISA to communicate with a serial port.
Serial Quick Reference GuideAlso, if you open up Find Examples in LabVIEW and search for "serial," several great programs will come up that detail how to send and receive strings using VISA functions. If you have any more specific questions regarding your application, please feel free to post them and we will do our best to try and help you.
John M
Applications Engineer