DAQ setup

[Charles_CLA]

That sounds like it is appropriate. I checked your DAQ express VI and the Max/Min is set to +10 and -10V respectively. This could be the problem as I suspect the bridge is giving either milli or micro volt changes in response to the strain. Another stupid question... if the wheatstone bridge produces a resistance change, don't you have to excite it with a current source? Does the 6210 provide that for you?

Charles

[Coulton]

Not a stupid question. The 6210 does have a power supply option, but the goal is to run 5V through the circuit and the 6210 doesn't have enough power. I probably should have mentioned this before (stupid of me not to) the powewr supply I currently am using is somewhat broken in the fact that the voltage drops to .3V when the load is applied. Being that eventually I will have a 5V power supply I don't think this is too big of a problem right now since the 6210 should still be able to read the change in voltage. If it does need the 5V then I am just spinning my wheels. I won't have the good power supply until Thursday so I wanted to troubleshoot everything else. If you believe the 0.3V is too small let me know so I can stop pestering you. 😃

[Coulton]

I also changed the range to +/- 1V

[Coulton]

I just checked with a separate sample that was built to over emphasize the bending of the specimen and it shows I am getting a reading so I think it might be the low voltage that is making it difficult to determine the change in voltage.

Another quick question though, how do you turn off the autoscale on the front panel graphs? To add to this do I change the ammount of points within the graph in the front panel graph or in the DAQ.

Essentially I want to see a long continuous line showing the changes in voltage. Right now with the autoscaling on, the points get discarded quick with new points. DO you understand what I am saying?

[Coulton]

I am leaving work for the day, but thank you so much for your help!

[Charles_CLA]

---

@Coulton wrote:

I just checked with a separate sample that was built to over emphasize the bending of the specimen and it shows I am getting a reading so I think it might be the low voltage that is making it difficult to determine the change in voltage.

Another quick question though, how do you turn off the autoscale on the front panel graphs? To add to this do I change the ammount of points within the graph in the front panel graph or in the DAQ.

Essentially I want to see a long continuous line showing the changes in voltage. Right now with the autoscaling on, the points get discarded quick with new points. DO you understand what I am saying?

---

You have asked two different questions here 🙂

1. Autoscaling can be turned off by right-clicking the graph and selecting "Autoscale X" or "Autoscale Y"

2. The reason that your data is only showing the most recent is that you are only plotting the data that comes directly from the DAQ Assistant VI. You should plot the data in your shift registers.

Another observation from looking at the code, you are casting all 100 points of data down to a single scalar. Try taking the mean of the data and see if that gets you anywhere. This might be the underlying cause of why you aren't able to filter out noise. Please try the attached code and let me know how it goes.

Charles

[Coulton]

Unfortunately I don't have Labview 2011 so I can't read your Labview, but based off of what you wrote this is what I got. I tried to follow your advice about placing the graph at the shift register, but I got nothing. Perhaps a screenshot of where it should be whould work. I placed the graph after the build array, but came up empty handed. Let me know what you think about the rest of the file. Thanks!

[Charles_CLA]

what version of LabVIEW are you running?

[Coulton]

On the computer I will be running the labview for the experiment, 2009. I have access to a computer that runs 2010, but I would only use it to check a VI.

[Charles_CLA]

Try this one.