SCXI and DAQ issues

[Yossi]

Hello all,

I'm using the SCXI-1143 connected to the PXI-6143 S series DAQ.

I have two issues:

1. How do I configure the Voffset of the SCXI module from labview? for example, if I try to acquire a signal that varies from -3.2 to -2.8 V, and I would like to use the maximal gain, I would like to offset it by 3V so the SCXI will amplify a signal from -0.2V to 0.2 V, so my samples will have the maximal DAQ resolution.

When I samplt today, no gain is appled, as the signal is about -3V which is close to the SCXI voltage limits (-5V).

2. Other issue.

When I sample a nice signal (almost with out noise), I get it nice but some times I get spikes in the voltage samples, of about 100mv to 400 mV. I'm using the S series, so this is not cross talk, so do you have any idea what can cause such phenomena?

Thanks in advance,

Yossi

[Neville D]

QUOTE (Yossi @ Oct 14 2008, 06:55 AM)

When I sample a nice signal (almost with out noise), I get it nice but some times I get spikes in the voltage samples, of about 100mv to 400 mV. I'm using the S series, so this is not cross talk, so do you have any idea what can cause such phenomena?

Bad ground? Do you see the spikes with an oscilloscope as well? Does the card you are using have isolated channels? I find the best way NOT to have noise issues is to use isolated channels, but this can get expensive pretty quickly.

N.