Deadzone When Measuring Piezoelectric Accelerometers Using Measurement Computing USB-1808X

[Nicholas_ATI]

Hey all!

First time poster. Hoping for some assistance. 

As the title suggests, I'm measuring some piezoelectric accelerometers using a USB-1808X. The accelerometers are powered by a signal conditioner built by the same company I bought the accelerometers from, so to be clear I am NOT attempting to power the piezos from the DAQ.

- Collecting all 8 channels at 50Khz

- 4 channels are load cells, and are reading as normal

- 4 channels are reading accelerometers. I've seen many normal tests, but recently I've been seeing deadzones (see included picture). 

- Outputting to TDMS and also outputting via python library and MCAP file.

Can anyone help me find a starting point to debug? 

 

[Fausto]

Hello @Nicholas_ATI.

19 minutes ago, Nicholas_ATI said:

I've seen many normal tests, but recently I've been seeing deadzones (see included picture).

Please elaborate. 

Where is the 'deadzone' in the picture?

Does the deadzone appear during what starts off as a normal test?

Have you checked your Python code or software application?

Can you reproduce the deadzone with DAQami?

Is there an issue with your signal conditioner, sensors or cables?

Regards,

Fausto

 

[Nicholas_ATI]

Hey Fausto, thanks for the reply. 

 

• The deadzones are the flat areas at the beginning of the collection and towards the center. These are samples of the behavior and over the course of long captures we see many deadzones in-between sections of useful data. 
• The deadzones appear in all tests. To clarify, they do not only appear at the beginning, but throughout the test.
• We have used the MCC python library and Daqami (TDMS output) to reproduce the condition. 
• I am also contacting the signal conditioner company. Sensors and cables have been checked and are working fine. 

 

One interesting thing to note is I have tests using this exact setup from September where the deadzone does not appear. One potential cause that has come to mind is a grounding issue with humidity affecting it.

[Fausto]

Hello @Nicholas_ATI.

To rule out the input channels, disconnect the sensors signals to the USB-1808X.  Connect the +VO terminal over to the CH#H terminal(s) and the CH#L terminal(s) to the AGND terminal.  Run you example and/or DAQami.  Any signs of a deadzone?

Regards,

Fausto

[Nicholas_ATI]

Fausto, 

Test performed. No signs of a deadzone, output is hovering at 4.8VDC. 

 

[Fausto]

Thank you for the update.  The USB-1808X appears to be functioning correctly.

Let us know when you have more information regarding the signal conditioner, since you verified the sensors and cables are working fine. 

Any chance your DUT goes static which is indicated by the deadzones?