daqmx

[twophoton]

Hello Friends:

I have been testing the sample program of 'Cont Acq&Graph Voltage-Int Clk-Analog Start.vi.' I got some questions whic puzzled
me a lot.

I have a PCI 6251 card and  DAQmx 7.4 and LabView 8.0 installed in my PC.

My questions are:

1) In the sample program I had to set the measurement range and timing parameters (rate and samples to read). However,
in Measurement & Automation I had to set the same things too. But which settings determine the measurement. When I set
the Signal Input Range as MAX 10 and MIN -1 a sine signal (ai0 channel) was still displayed with its part below -1 volt.

2) The diagram of the settings of the 5 switches did not work. If I selected the Factory Default Setting ( S1 and S2 both left, S3,
S4, and S5 all down) the signal displayed in the graph drifted downward continually and finally below -10 volts! If I switch S4 up
and kept others unchanged the signal seemed right with its applitude and 0 level same as which displayed in an oscilliscope.
I adopted NRSE terminal Configuration with signal connected to AI0 and grounded to AI SENSE. Was my switch setting correct?

3) If I want to adapt this sample program to measure only the positive part of sine signal how can I do? I want every pulse of
the sigal to be triggered independently.

Regards,

Jin

[Hal_L]

Hi Jin,

If you are using LabVIEW 8.0, then you need to download DAQmx 8.0 as well. Setting the voltage limits to not include negative readings is not going to filter out that data for you. The easiest way to get only the positive portions of the sine wave is simply to acquire all of the data and then filter out the negative readings in post processing.

However, for NRSE configuration, your connections are correct with the signal connected to AI0 and the ground to AI Sense. Is there a specific reason that you chose this configuration? Here is a link with more information on these configurations: Field Wiring and Noise Considerations for Analog Signals.

I am not sure what switches you are referring to in your second question and I am not sure exactly how you want to trigger your signal. Could you please be more specific?

Regards,
Hal L.