signal cross talk on pci 6014?

[jimmyinct3]

I am using a pci 6014 with a scc 68 wiring box two acquire two analog signals.

In AI 12, there is a amplified strain guage signal which spans 0-10v.

In AI 5, there is am amplified DC LVDT signal which spans -5 to +5V.

A respective ground from each sensor goes to the scc break out box.

When a sinusoidal signal is applied to the load cell, some of that signal is seen on the LVDT channel.

Yet, the LVDT has the core removed and is a large distance away from the project.

This strain guage signal shows up around 2V peak to peak on the lvdt channel.

Yet, if I stimulate the LVDT, I can see the signal clearly in both labview and on an oscilloscope.

None of the LVDT signal is seen on the load cell. 

If i place an oscillosope on the LVDT output signal, the signal appears clean down to 20m regardless of strain guage stimulation.

It is only when plotting/charting in labview that Im seeing the strain signal on the lvdt channel.

Ill attach an example file from ni which is modified to read two channels at the same time, and the problem can be seen with this file.

I doublt the programming is the is the problem though.

Message Edited by jimmyinct3 on 11-13-2009 03:19 PM

[jimmyinct3]

i was able to plug in the signal to ai13 rather than 5

im now seeing seperate signals rather than merged signals.

[TCPlomp]

Have you terminated non-connected signals with a 50 Ohm resistor?

I am not familiar with the 6014, but it might be an ADC with one converter, adding a terminated channel in between two channels might be a good idea if so.

Ton

[Kodeeswaran]

Try grounding the unused channels, R u using the DAQ assistant where all the scales and channels are configured using the signal express DAQ Assistant, If so there might be a chance of channels misconfiguration ensure this also, try reading in the measurement and automation only the particular strain gauge and LVDT channels,

[jimmyinct3]

i posted a vi that had the cross talk issue.

that meaning that the AI12 signal was showing superimposed on AI5 signal.

There was no daq assistant.

Its straight from the example files.

To answer the other question. Using 50 terminators on used channels to ground didnt make a difference.

And it is a brand new board and breakout box so i doubt they are defective.

Each of the input signals works fine and they look perfect on the oscilloscope, its something internal to the pci card.

I moved one of the signals from AI5 to AI12

The signals are now sepearate and I should be good to keep plugging.

Thanks for checking in.