FieldPoint Family

cancel
Showing results for 
Search instead for 
Did you mean: 

Problem acquiring data with cFP-AI-100

The vi we are trying to design is very simple, just trying to acquire 2 channels, however the sensors in question have both a high and low output, so I have written the VI to acquire 2 channels, one for the high and one for the low of each sensor, and used the express formula function to obtain the difference between them, multiplied by a number to give us a true pressure.  We do get a signal bouncing around 0, but don't seem to be acquiring anything other then backround noise.

I've attached the VI as this is my first attempt at working with compact fieldpoint, so I just want to see where i've made my mistake
0 Kudos
Message 1 of 4
(4,842 Views)
What kind of sensor are you connected to?  Why are you wiring the high of a sensor to one channel and the low to another channel?  The cFP-AI-100 uses single ended inputs relative to a common ground.  If you don't tie one side of the signal to Common, the single lead is going to have a floating voltage level.  The channels are isolated from each other so there is no voltage reference from one lead to the other.
 
Here is a link to the manual.  http://www.ni.com/pdf/manuals/370278a.pdf
0 Kudos
Message 2 of 4
(4,835 Views)
we are wired to a pair of omega px302 pressure transducers, i'll check over the wiring a second time, and go back to placing the low end on common, excuse my inexperience with single ended modules, as in the 5 years i've used labview and NI equipment, i've never used anything other then differential mode
0 Kudos
Message 3 of 4
(4,824 Views)
Is there some other model of a PX302 transducer you are using?  I looked it up and came across this page.  http://www.omega.com/Pressure/pdf/PX302.pdf  This is a strain gage bridge transducer.  4 wires.  2 for bridge excitation and 2 for sensing.  I am using these (or at least ones similar to these.)  I use the cFP-SG-140 module to read them.
 
Definitely take a close look at your wiring setup.
0 Kudos
Message 4 of 4
(4,817 Views)