Problem regarding Loop back test in NI USB 6009

[seetha92]

Hello !

I am using NI USB 6009 for my experiment. While performing the loop back test, I observed that the test seems to be successful for RSE mode whereas it shows a consistent difference of 1.4 V between analog output and input.

The following were the results obtained:

Differential mode:

AO0 = 1.5 V =>  AI0 = 0.1 V

AO0 = 2.5 V => AI0 = 1.1 V

AO1 = 1.5 V => AI1 = 0.1 V

RSE mode:

AO0 = 1.5 V =>  AI0 = 1.49 V

AO0 = 2.5 V => AI0 = 2.49 V

AO1 = 1.5 V => AI1 = 1.49 V

Could someone explain as to why is this happening?

[aputman]

It sounds like your device is damaged.  This user had a similar experience. 

[GerdW]

Hi seetha,

The following were the results obtained:

Differential mode:

AO0 = 1.5 V =>  AI0 = 0.1 V

AO0 = 2.5 V => AI0 = 1.1 V

AO1 = 1.5 V => AI1 = 0.1 V

Did you notice the different pin naming when using differential mode?

What did you wire to AI0+ and AI0- when measuring? How did you wire to AI1+ and AI1-?

[seetha92]

Hi GerdW,

Thanks for the reply.

Please have a look at the attachment. I cross-checked my connections lot of times. So, there is no scope of wrong wiring or loose contact.

[seetha92]

Hi aputman,

Well, I can't say for sure. I tried cross-checking the DAQ measurements of my experiment with the measurements obtained from the oscilloscope.

For the experiments, I am using AI0+ terminal along with the GND, in RSE configuration. The values weren't crazy. I guess the problem is only with the AI0- and AI1- terminal.