timed multichannel acquisition of channels with different gains

[Dimon]

I am looking for an example of VI or advise how I can acquire data from three channels (temperature, pressure and distance: millivolts, volts and volts) in time (so that each data point is referred to an elapsed time) and record it in a spread sheet file.
The typical examples are not straightforward and I do not know how to add time to a waveform or how to "disassemble" a set of data to process each column separately.
The straightforward use of three "Scan 1 Channel".VI placed in a while loop provides all necesary features but implement huge interference between channels so that I cannot read temperature.

I am using LabView 5.0.1 and Keithley KPCI-1801HC DAQ board with 32 differential
channels, OS - Windows NT 4 with SP6.

Thank you in advance for your help.

Dimon

[Ronald]

For long time DAQ it's always a good idea to scan for some time and take the
average of the result. When measuring a signal you also measure the noice
(especially when measuring voltage signals). Acquire a waveform and use the
mean function. (0.1 seconds, 10kS/s or something).

Hope this helps for the 'interference'-problem

Ron@ld

Dimon schreef in berichtnieuws
506500000008000000BE180000-984882144000@quiq.com...
> I am looking for an example of VI or advise how I can acquire data
> from three channels (temperature, pressure and distance: millivolts,
> volts and volts) in time (so that each data point is referred to an
> elapsed time) and record it in a spread sheet file.
> The typical examples are not straightforward and I do not know how to
> add time
to a waveform or how to "disassemble" a set of data to
> process each column separately.
> The straightforward use of three "Scan 1 Channel".VI placed in a while
> loop provides all necesary features but implement huge interference
> between channels so that I cannot read temperature.
>
> I am using LabView 5.0.1 and Keithley KPCI-1801HC DAQ board with 32
> differential channels, OS - Windows NT 4 with SP6.
>
> Thank you in advance for your help.
>
> Dimon

[Dimon]

Thank you. But noise is not my problem. In the case of using three "Scan One Channel".VI, the millivolt reading on one channel in LabVIEW becomes nearly proportional to the voltage reading on the other channel.

[Raecine Meza]

I realize that you have already looked at some of the examples, but perhaps you have missed the Datalogger to Spreadsheet File example. I have this example in LabVIEW 6 with NI-DAQ 6.9 installed. You can request three channels with this example by using the correct channel string input. For example, "0:2" is channels 0 through 2. The chart in the example is already set to a time format and it is all being nicely saved to a spreadsheet file.