Multifunction DAQ

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Periodic DAQ shutdown

Using an OEM USB-6008 I am experiencing the same symptoms described in the post below:

 

http://digital.ni.com/public.nsf/allkb/D44312CF1A49FD638625723A00192681

 

However, I have removed all devices from the 5V line and the problem persists.  Are there any other causes of this sort of shutdown aside from overdrawing from the 5V line?

 

I am currently using 3 analog output lines for 0-5V control signals and 1 analog input to recieve 0-5V signals.  I am also using the 8 channel digital output.

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Check your USB bus power settings in Windows.  Windows 7 has this feature where it will turn off the USB bus power to save energy.  You can go into the device manager and turn that off.


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Thanks for the quick advice!  I've changed the setting and it is still occurring.  I am using the 8 channel digital output to control this relay board:

https://www.futurlec.com/Relay_8.shtml

 

The shutdown seems like it usually occurs while relays are being switched.  Is it possible that this could cause the DAQ shutdown?

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The 6008 has open collector outputs.  Which mean all of the driving current is coming from the 5V.  What is likely happening is when you have many relays turned on the DAQ goes into a power reset mode.

 

I would add another 5V power supply to pull up the lines.  This will allow some extra current to drive the relay controls.  Something like a 1kOhm would be a good pull up.


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Could also be a large reverse-current spike from the relays... make sure there's protection diodes in the conditioning circuit.

 

http://en.wikipedia.org/wiki/Flyback_diode

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I've looked more closely at the relay board, and it looks as though it has built in flyback protection, so that is not likely the problem.

 

With regard to adding another supply to "pull up the lines", I am fairly novice with electronics and want to make sure I do this properly to avoid damage to the DAQ.  Does the diagram below show what you were describing crossrulz? If not would you be able to help get me on the right track?

Capture.PNG

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I've looked more closely at the relay board, and it looks as though it has built in flyback protection, so that is not likely the problem.

 

With regard to adding another supply to "pull up the lines", I am fairly novice with electronics and want to make sure I do this properly to avoid damage to the DAQ.  Does the diagram below show what you were describing crossrulz? If not would you be able to help get me on the right track?

Capture.PNG

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That is exactly what I am proposing.


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