simple parallel port control

[kevinhy]

Hi, I am new in programing and what I need to do is to maintain 5V on 4(any 4, cause I can hook the wires to any pins I wanna to) of the 25 pins of the parallel port. and at specific time I need to press a button to let the voltage drop(a signal) to active the machine I am working on. Can any one give me a lift on what vi to use? I check the NI tutorial but it all talks about how to send and recieve 8 bits info over the parrallel port while what I really need is just a simple program to control 4 pins. I am using windows XP pro and labview 7.0

[MCP]

First of all read this arcticle about the Parallel Port
http://zone.ni.com/devzone/conceptd.nsf/webmain/72C6FC6CE4AD4D1386256B1800794596

After that downaload the Accesshw.zip which allows you to write and read from any computer's port under windows.

Now if you want lets's say to write to the 1st bit of the parallel port you have to put to the parallel's port data address the value 1. In order to leave the other bits unaffected you have to keep somewhere the state of the parallel port and use the following condition [state OR 2***bit_number] if you want to turn on (1) this number. On the other hand if you want to turn it of use [state AND NOT(2***bit_number)]

Please let me know if you need more information

[kevinhy]

Thank you very much! but I don't quite understand the condition you posted, can you give a sample vi?

[kevinhy]

also, I have download the Access_Parallel Port_with_VISA VI do you think I can use this one? sorry I can't try it out on the machine yet, becasue this is an old high power X-ray machine and we need to make sure what are we doing before firing to prevent potentially dangerous X-ray radiation.