For the past 30 years, National Instruments has been a technology pioneer and leader in virtual instrumentation - a revolutionary concept that has changed the way engineers and scientists in industry, government, and academia approach measurement and automation.
LabVIEW, Data Acquisition, Modular Instruments, PXI, Programmable Automation Controllers.
Here is a page from an old NI Catalog. RS-232 Tutorial of NI. drag-drop image to read.
National Instruments - Test and Measurement
One which is useful for beginners is the LabVIEW Student Edition - LabVIEW easily connects to any device be it hardware or outside applications like Microsoft Excel. You can depend on this seamless development experience as you write your program.