NI myDAQ Reset?

[DJ_Moore]

Hello Everyone!

I am currently a student at ITT, and I was doing a lab for one of my assignments. While I was doing this lab, I had accidently hit "RUN" on the V-DC setting when I had the probes configured for A-DC. When I reconfigured the probes to the correct configuration, I set the NI myDAQ to "Specify Range" and "Run Continuously" and then hit "RUN". Without me connecting the probes to anything or touching anything, and even with the probes not connected to the device, the myDAQ suddenly gave readings from -600.00 mV to ~200.0 mV. I read somewhere that I can reset the device. If so, how can I do this? Many thanks, Derrick.

[Kristoff2]

Hey Derrick,

If the probes are not connect to anything that means the input are floating (ie nothing connected).  It is hard to predict what will happen in this situation and you'll often read noise.  This is common to most analog and digital input and is one reason that some inputs will have pull up or pull down resistors attached.

If you connect both the red and black probe to ground do you read a smooth 0v?

What if you try to read the voltage from a battery?

It's likely that everything is still working fine, but let us know if the answers the the questions above are not what one would expect.

Thanks!

-Sam K

LabVIEW Hacker

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[DJ_Moore]

Hello Sammy!

Sorry I havent been able to reply as soon as I should have- I have been quite busy.

When I was testing the circuit that I built on the voltage setting, I read 14.95v (what was expected) for a few seconds, then the readings started to swing wildly into the mv range. Since this is getting hard for me to explain, I have included an image. The test probes are not connected to the myDAQ. The situation has improve somewhat, (ie, no longer reporting readings as high as ~600mv) but it's still an issue. The settings that are used are Mode: Auto and Acquisition Mode: Run Continuously. In this case the myDAQ picked up voltages in the 200mV range and stuck there.

Another thing that I would like to add here is that when I switched to Mode: Specify Range - Range: 2v, the myDAQ read -0.000vDC. When I switched to the 20v and 60v ranges, the output read 0vDC. Also, when I switched on Null Offset, the readings increased on the 200mv range.

Many thanks for helping,

Derrick

[Kristoff2]

Hey Derrick,

In the picture you posted the myDAQ probes are not connected to anything.  In this case what I said about floating inputs applies and I would expect to see 'random' noise on the screen.  This is expected since the outputs are 'floating'.

What happens if you connect the probes to the myDAQ and connect them to a battery.  Are you able to read a steady voltage from the battery?

Thanks!

-Sam K

LabVIEW Hacker

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[DJ_Moore]

Hello Sammy,

The battery is reading a steady 1.591vDC.

Derrick

[Kristoff2]

Ok, good.  I'm pretty sure your myDAQ is working correctly then.

If you're still having trouble reading from your circuit can you provide some more information about the circuit.  Can you test other points in your circuit (such as the power rails) to confirm they are working correctly.

Thanks!

-Sam K

LabVIEW Hacker

Join / Follow the LabVIEW Hacker Group on google+