Our lab is transitioning from an older 486 computer using windows 3.1,
labview 3.1, and DAQ instruments connected via parallel port to a Far Point
Communications parallel port card installed in the computer. The
configuration of DAQ devices involves an SCXI-1200, SCXI-1100, and SCXI-1124
installed in an SCXI-1000 chassis.
The new machine we are moving to is a Pentium II machine with Windows 98,
and Labview 5.1. We are attempting to connect the DAQ equipment to this
machine through the standard parallel port on the motherboard, but seem to
be getting a constant reading on the pressures read from the SCXI-1200
analog inputs and the temperatures measured from the SCXI-1100 are all
reading within 0.1 degrees of one another. This is very odd because
previous temperature measurements from the old setup normally stayed within
a degree of one another but fluctuated normally.
The pressure measurements have found a steady base reading from which they
do not vary from for more than a few seconds, even when pressures being read
change significantly. None of the DAQ equipment has been changed between
the two computers. Changes in readings occur just depending on which
computer the parallel cable is hooked up to.
Additionally, multiple SCXI-1200 modules have quit functioning while using
the new computer. All tempuratures read a constant 470 degrees F, and the
pressures all fall to 0.01 inches of water and do not change when the 1200
fails. The 1200's have been replaced afterwards because of faulty analog
chipsets, but this has happened to 4 different modules, and only one of them
(approximately 3 years old) has shown signs of physical damage to the board
itself (according to the RMA report).
The SCXI modules operate in multiplexed mode, and jumper W-1 (or is it J-1)
has been changed from the factory default on the 1200 accordingly. I cannot
successfully install the old parallel port card in the new machine (Windows
98 does not successfully detect the new hardware), and I'm not sure if I
need to. Does the parallel port on my new machine not meet the standards
necessary for use with the SCXI-1200 module, and how can I tell for certain?
I've changed the BIOS setting to EPP, and all of our output functions from
the DAQ seem to be working properly, only the temperature and pressure
inputs from the 1100 and 1200 seem to be affected. If it is necessary to
install a second parallel port card (from Far Point or anyone else), can
someone recommend an appropriate card for use with NI equipment?
Fire Test Engineer