Measuring multiple piezoelectric voltage sensors at the same time

[Jonahvdm11]

I am trying to measure the voltage output of two sensors at the same time with the USB-6289.

I connected the two wires of one sensor to the top two ports in the figure below, and the other sensor to port 4 and 5 as displayed with the circles.

When looking at the signals measured with signal express, all signals display the signal of each sensor, so when there is an output of only one sensor both acquired signals show this output instead of just the one that outputted the signal.

Can anyone tell me what I am doing wrong?

thanks...

[santo_13 · Accepted solution]

1. You need to connect the Piezo signal to AI GND, not just AI+ and AI- - read more https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YIfVCAW&l=en-US
2. Your DAQ is a multiplexed ADC device and these are prone to Ghosting - read more https://knowledge.ni.com/KnowledgeArticleDetails?id=kA03q000000YHy6CAG&l=en-US

[Jonahvdm11]

Thanks a lot for your response,

What is the easiest way to accomplish this?

Do I need to connect another wire to one of the wires and connect it to AI GND?

Or do I move one of the existing wires to the AI GND port and thereby it is grounded?

'Jonah

[santo_13]

It all depends on your actual signal from the piezo sensor.

You can connect resistors to ground for both AI- and AI+ lines as shown in the below image.