There are a couple of ways to talk to the parallel port in LabVIEW. You can use NI-VISA to communicate with LPT1 (also known as, I think, "ASRL::10::INSTR"). This will let you do straight reads and writes, and assumes that the device uses pretty normal signaling. Under the hood, NI-VISA is using the Windows API to talk to serial ports, and this happens to work for parallel ports.
However, this won't expose the full parallel port functionality. In particular, you won't have control over individual digital lines on the port. So, if your device needs finer-grained control than just reading and writing data, you will need to use the Port I/O functions. Use the Example Finder and search for "parallel" and you'll find a couple of examples of how to do this lower level port I/O. Good luck. I hope this helps. Brian
