How to set NI6115 DC coupling mode?

[xsfl]

I use Analog Input:General Properties:Input Configuration:Coupling Property to set the coupling mode. But it doesnot work for NI 6115

how can I configure the NI 6115 coupling mode.

Thanks

[Brad_K]

Hi xsfl,

Could you describe what is not working? Did you get an error? Is the device still removing the DC offset when you select DC coupling? (If so, check your wiring to make sure AI0- is connected correctly.)

It might help to post a snippet of code showing how you tried to use the property node.

Brad

[xsfl]

Hi Brad:

Thank for your help.

I use signal generator (Stanford research system, Model DS335) to generate a 10Hz (Vpp = 4V, offset = 1V) square wave, the result is shown in "square wave result.jpg".

If I change to sin wave, and the offset is removed by the device.

I have attached the vi at here, maybe you can help me check it.

The connecter part, I use SH68-68-EP Cable, and connect to CB-68LPR (in CA-1000), and use BNC cable connect signal generate and the CB-68LPR board.

Thanks again.

Zhongyao

[Brad_K]

Hi Zhongyao,

Your code looks correct (though it is missing a call to DAQmx Clear Task.vi).

The NI 6115 uses a pseudodifferential terminal configuration, so swapping AI0+ and AI0- will not produce satisfactory results. Which terminals on the CB-68LPR did you connect to the function generator?

I've also seen similar behavior on a device with a bent pin 34, which prevented AI0- from making contact. Try visually inspecting the connectors.

Brad

[xsfl]

Hi Brad:

I have check the connector.

I use pin68 and 67.

And I try AI2 (pin 65 and pin 64) and  AI3 (pin 30 and pin29).

Same phonomenon.

Do you think the Ni6115 is out of order? Is it need to be check or repair?

Zhongyao

[Brad_K · Accepted solution]

Hi Zhongyao,

You need to connect the negative lead to AI0- (pin 34), AI1- (pin 66), AI2- (pin 31), etc. Pages 4-6 through 4-15 in the S Series User Manual have all of the details.

Brad

[xsfl]

Hi Brad:

That is it. I connect the AI0- to GND. Everything is perfect.

Thanks alot.

Zhongyao