PXI 1082- 4MS/s card

[panoskak]

Hi guys,

I face a problem about noise added up into my signals. This appears to every single channel, connected or not to a probe and

thus this is not my fault. I attached a screenshot, because you may know how to get rid of this.

link

Thank you in advance!

[Ben-N]

Hey panoskak!

The link you attached doesn't work.  Can you repost that screenshot?

Thanks!

[panoskak]

Thanks, now is alive again. link

[Ben-N]

The noise is definitely cyclic, which makes me think that this is coming from an external source.  You mentioned that this noise is the same regardless or whether you have anything connected or not.  What modules do you have in your 1082?  Can you give us an idea of what your system setup is?  Based on the image you provided, it looks like that noise may be a cyclic 120 Hz signal.  Do you have anything around your system that is running at 120 Hz?  Is your system in a room that has a lot of fluorescent lights in it, or is very close to a power supply of some sort? 

I would suspect that this noise is coming from something in your environment, the issue will just be pinning down what that source is.  Get back to us with some more information and we can definitely try to see what's going on.

[panoskak]

Hi,

yes you are right. The PXI is in a laboratory with about 100 fluorescent lights. The card attached to it is NI PXIe6124 Series S.

I mentioned that this noise is the same regardless or whether I have anything connected or not, but this is not right. I have connected the probe, but the probe may be or not connected. I looked it again yesterday, sorry for my mistake. Today, we will change the NRSE/RSE switch to see the changes.

The problem may be that we considered a non grounded system. We checked in the manual, and found sth about ground loops and the NRSE/RSE switch. I will post again the results and photos of our system if the problem persists.

Thanks!

[Ben-N]

Hey panoskak!

No worries at all.  Definititely let us know what the results are so we can help figure this out if fixing the ground doesn't work!

[panoskak]

We found the solution, supposing that this is the best solution. We had a floating signal and used the single ended option with the RSE switch on. The problem was not the lights, but a transformer. We used a transformer 240/24V and a bridge to supply our LEM transducers and this was our common point for our measurements. This was the reason for the 100/120 Hz noise.

In your previous post you said that sth with double frequency is the reason, and the only responsible for this was the bridge and the transformer. Even in the case we did not supply the measuring devices, but the transformer was under voltage caused this noise combined with the common point. Do you know any possible reason for this? Floating common point created by a transformer 240/24V and a bridge with electrolytic capacitors supplying a Traco dc stabilizer, the output supplies the LEM and creates the floating common point. This caused the strange noise...

The noise, however, appeared and in the case of the disconnected probes. This was due to the RSE/NRSE switch and the differential option. In order to eliminate this noise we put capacitors in our floating common. This caused the "uniform" noise...

Thanks for your interest...

[sumeet_PE]

Would like to know how can I use NI PXI 1082 modules remotely.
We have 4 PXI slots but 1 machine to operate, we exactly want to utilize the remaining 3 PXI slots remotely using different host machines wherein acquired data will be sent directly to the labview residing in host PC.

Can Anyone let me know how to do this and if possible post example on the same comment