noise PXI 1520

[oliboiss]

Hello

i have a small VI where i read a LVDT with a PXI 1160 and a Strain gage with a PXI 1520. If i read the strain in first i have no problem but if i read the LVDT in first the strain have a big noise (0.5 volt). What is the problem?

Thanks a lot

Oliboiss

[oliboiss]

this a word picture of the VI with two probe

[Laura F.]

Hello Oliboiss,

What sampling rate are you using?  Does this problem go away if you decrease your sampling rate?  What type of SCXI module do you have your LVDT connected to?  What SCXI modules are in your system, and which are you using as your communicating module?  Check that which ever module you have listed in Measurement and Automation Explorer (MAX) as your communicating module, is the module that actually has a cable connected to it if you are using a stand alone SCXI chassis and not a SCXI/PXI combo chassis.

Regards,

Laura

[Olibois]

Hi Laura

I change my sampling rate and i dont see amelioration. I use a sampling rate of 2000 pt/sec. My LVDT is connect on a SCXI 1102c with a terminal block SCXI-1303. (not 1160, sorry). I have too a SCXI 1520 with a terminal block SCXI-1324 and a SCXI-1160 with a SCXI-1324. All module are connect on a PXI-6052E with a multiplexed mode.

I have also a PXI-6733 with an external terminal block BNC-2110 but i dont use it at this moment. I send u a print screen of the MAX for help u because i'm a beginner. So if u have more question reply me.

Thanks

Oliboiss

P.S. Sorry for my bad english

[Olibois]

Hello Laura

I make an another test with the same VI. I change the input range of the task. with a -2 to 2 volts i find a noise of 0.1 volt but if i use an input range of -10 to 10 volts i find  a noise of 0.45 volts.

What's my problem??

Thanks

Olivier

[johnsold]

Are all the unused channel inputs grounded? Floating inputs on mutiplexed devices can often produce strange results, especially if the signal magnitudes are quite different. I am not familiar with your specific equipment, so consider this a generic suggestion.

Lynn