USB6008 output

[Dibbs]

Hi,

I have been asked to plot the voltage output of the USB-6008 vs the input of the NI-9234. The cards are linked together, so the NI-9234 should read exactly what the USB-6008 sends it to.

But there is a strange phenomenom that happens, the NI-9234 is unable to read the signal under 3.5mV. I do not know where this is coming from, do you have any ideas?

Could this be from the USB-6008, or the NI-9234?

On my graph, the white line is the signal that i am sending to the usb-6008 (ideal signal) and the red is the input of the NI-9234.

Thank you

 

[Henrik_Volkers]

Take a deep look into the spec of the 6008, without doing so , I assume the output offset of this cheap device is in full spec 😉

[jschwartz · Accepted solution]

Hi Dibbs,

We are looking at a couple things here - the AO accuracy of the 6008, the AI accuracy of the 9234, and the  use case of the 9234.  The 9234 is a DSA device so is it is optimized for acceleration and vibration measurements - not low frequency/DC measurements.  The offset error of the 9234 is 7.1 mV and the absolute accuracy of the 6008 AO is 7 mV, up to 34 mV at full scale. One thing you could try doing is using the AI of the 6008 to characterize the 6008 AO or use a device optimized for DC measurements, like a DMM.

6008 AO Specs

9234 Accuracy Specs