I've created a glamorized DAC that I wish to control using LabView software. I have already developed the control part of the software in LabView but I do not know how (or even if it's possible) I could use LabView to read and write digital I/O through a LPT port when I am not connecting it to a DAQ device. My interface does use a 8255 PPI. My operating system is Windows NT. I have heard that C can be used to access a LPT port directly and read/write data without using a communications protocol. I know that LabView can call C code but I have yet to find a reference manual which explains the process of directly writing to a port in C. If you have any suggestions, I would greatly appreciate them.
In LabVIEW Technical Resource, Volume 2, Number 4 there was an article covering how to access the standard Centronics parallel port. Unfortunately this port only supports writing of data so this only covers half of your problem. /Lars-Goran
You can use the "In port.Vi" and the "Out Port.Vi". This VIs are located on "Function/Advanced/Memory palette . This VIs read and write data on a port. I'm sending a file created by Rolan Yang that show how to read and write to the LPT1 port. This file can run on the windows qbasic.
