nightlight wrote:
> i have been trying to output a digital value using parallel port. i
> know there are two ways to do that. one is to use visa and the other
> is portin and portout function. The labview version i am using is 6.i
> student edition, so it doesn't support portout with the accessHW
> function. therefore i am left with only visa. i have some difficulty
> in getting it work. i grounded pin 11 and pin 12, and tried to use a
> multimeter to measure the voltage between the one of the data lines
> and ground. i thought when i ran the program and adjust the value that
> i output to the port, the value i read from the multimeter should
> change between 0v and about 5v according to the value i give. but i
> never changed, always stayed at 3.3v. could anybody te
ll me the
> possible reasons?
Well, I guess the student edition does not have support for the Call
Library Node, does it?
Otherwise you could go to
http://cvs.sourceforge.net/viewcvs.py/opengtoolkit/portIO/
where you will find the files to do what the accessHW library is
supposed to do. It works for me for NT4, W2K and XP, but I haven't
tested it on W9x although it should work there too.
That about the logic levels of the parallel port: don't expect to good
voltages on a notebook computer and even desktops do have some problems.
0.8 V for logic 0 is sometimes already quite low and 3.3V for logic one
can also often be the max you can expect.
Rolf K
