Noise problem PCIe-6259

[marianomosk]

Hello,

I'm having some issues with a PCIe-6259. The problem is with all the analog inputs, there is noise in all of them. In order to remove signal conditioning from the problem I've disconnected all the signals, and I was hope of a solid 0V, but I instead of this there is a 0,02 Vpp oscilating signal (see attached screen shot). Is it possible that the PC is generating the noise? Are there PC minimum requirements in order to avoid noise???

Thanks

Mariano

[Dennis_Knutson]

Disconnecting the inputs will not give you a 0V reading. What you are seeing is normal with floating inputs. If you want to read 0V, you need to GND the inputs.

[marianomosk]

Ok, see the attached file. That is a AA battery conected to channel 0 in my SCB-68 block with a shielded cable to the PCIe-6259. With the input range the resolution is 0,000320 V, and the signal has a 0,02 V pp. That is noise I'm sure. Can be the PC?

Mariano

[Dennis_Knutson]

You are doing a differential measurement. What pins on the SCC-68 do you have the battery connected to?

[marianomosk]

Dennis,

I made a mistake, the battery wasn't conected properly for a differencial measurement.
I corrected that conecting the positive terminal of the battery to AI0, the negative terminal to AI8 and I also wired AI8 with AIGND, I think that's the correct differencial conection for a floating signal source as a battery. I ran the test panel and I saw a rms noise of about 0,002 V. This is 10 times better that in previous situation, but It's still to much taking in count that for a +/- 10 range the resolution is 0,000320 V. The battery is wired to the block terminal with a short wire (1 ft), and I look at the signal with high resolution DMM and the signal is perfectly stable in 1,517 V

Thanks for your interest.

Mariano

[Jgstchuy]

Buenas Tardes

Siempre pudiste resolver lo del ruido.....yo tengo el mismo problema.....tengo un ruido que no puedo disminuir de +/- 5 mV en mis entradas analogicas de una tarjeta PCI6320? Que podria hacer para reducir este ruido a menos de +/- 1 mV?