Comparison of EMG from NI 9234 and NI 6210

[Haritha]

Hello,

We are students from Oklahoma State University and we are working on a project where EMG data is collected using NI 9234 and NI 6210.

When we posted in the forum earlier while asking for suggestions of what board would be suitable for EMG data acquisition, some engineer from NI replied saying USB 6210 is enough for getting EMG signals. We had already got NI 9234 for some other project. We tried using both the boards for EMG data acquisition. But from the results, it looks like NI 9234 gives better signal than NI 6210. The signal from 6210 is dominated by noise.

I am using same kind of configuration for both the boards.

1) Pseudodifferential mode for NI 9234 and Differential mode fro NI 6210.

2) We are using Myoscan sensor interfaced with Sensor Isolator from Thought technologies as input to both the DAQ boards

3) The voltage range set for both the boards is -5 to 5 millivolts

I would like to know why the signal from NI 6210 is dominated by noise and whether is there any way to improve the signal.

I am attaching the screen shot of both the outputs for your reference.

Thanks,

Haritha Srinivasan

[Carisa_L]

Hi Haritha,

How is your sensor connected to the NI 6210? How many EMG signals (or other kinds) will you be working with? Are both devices necessary for the application? As an additional side note, the NI 9234 is a more precise device and has higher resolution than the NI 6210. Hopefully we can improve the signal from the NI 6210.

Cheers,

Carisa

[Haritha]

Hi Carisa,

We tried to connect the Pins 17 & 18 of the 6210 and formed a Differential pair. It seems that it is working, but is still dominated by Noise.

Then we tried connecting Pin 19 with Pin 28 (Ground) and it worked in RSE mode. The signal was better than the Differential pair.

Apart from the above two cases, it is not working for any other Differential Pair or RSE configurations.

Also whatever EMG signals we are getting from 6210, it is either fully in Positive Voltage or Negative Voltage scale. Normally the peak-to-peak EMG signals should be both in Positive & Negative scales, which we are getting perfectly from NI 9234.

I would like to know the reason behind this difference of EMG signals from both the devices and also about the Pin Configurations.

Attached are screenshots of the signals we are getting from 6210.

[Carisa_L]

Hi Haritha,

I've linked to two documents below that should be able to help you with the wiring and noise you're experiencing with the 6210.

Field Wiring and Noise Considerations for Analog Signals: https://www.ni.com/en/shop/data-acquisition/measurement-fundamentals/field-wiring-and-noise-consider...

6210 Manual (Pinouts on page A-2): https://www.ni.com/docs/en-US/bundle/usb-621x-manual/resource/usb-621x-manual.pdf

How to Eliminate AC Noise: https://knowledge.ni.com/KnowledgeArticleDetails?id=kA00Z0000019MnMSAU&l=en-US

Please read through these, try some of the suggestions and let me know how these work out for you.

Thanks!

Best,

Carisa