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U6 measurement of 8 different voltage values

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5 replies to this topic

#1 kleanthise

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Posted 05 June 2014 - 04:12 AM

Hello guys, 


I recently bought a labjack U6-pro 

I manage to communicate with it using python .

I want to use it in an application where i am going to get eight different values of voltage and store them in a text file on my computer.

My problem is that at the moment i have just connected two AIN0 and AIN2 to a voltage source with a small resistor so as to have a tiny voltage difference.


import u6, time
d = u6.U6()
{'BootloaderVersion': '6.15',
 'FirmwareVersion': '0.88', 
FileName = r'Z:\TFTS-PC\Labjack_2101493.txt'
SleepTime = 1 # wait time in seconds    
fileHandle = open ( FileName, 'a' )
fileHandle.write ('Time\tT1(K)\tT2(K)\tT3(K)\tinpV(V)\tVDev(V)\tR(ohm)\n')
for i in range(1,100):
    input0 = (d.getAIN(0))
    input1 = (d.getAIN(2))
    print input0, input1
I am using the above code but the output it fluctuates a lot.
Is there any solution to that? 

#2 LabJack Support

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Posted 05 June 2014 - 11:57 AM

So you have too much noise or variation?  Start with this app note:




Start by jumpering AIN0 to GND and AIN2 to GND.  You can then take readings and confirm that the U6 performs similar to the noise levels from Appendix B of the U6 User's Guide.

#3 kleanthise

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Posted 16 June 2014 - 09:09 AM

Thank you very much for your quick reply. I recently bought a relay driver 

LJU39RL8 - Relay Board for the LabJack U3 and U6 and is connected to labjack U6 using the DB15 connector .

I am using the following code


d.writeRegister(EIO0_STATE_REGISTER, 0) 
d.writeRegister(EIO1_STATE_REGISTER, 1) 
To enable relay 1 and disable relay 2 but it seems to doesnt work when i set both values to 0 to enable both relays and when i am setting them to 1 it disables both . Am i doing something wrong ? 
Thanks again

#4 LabJack Support

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Posted 16 June 2014 - 09:23 AM

I don't quite follow what does work and what does not work?  Please clarify.

#5 kleanthise

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Posted 17 June 2014 - 04:38 AM

I can see that when i enable the relay lets say relay 1 and relay 2 i get the output measured from labjack correctly. When i disable both of relays it gives me 0 output that is correct but when i am trying to use a combination of either relay 1 or relay 2 on the output seems to doesnt respond correctly. Is there anything wrong in the code that i am using ?

#6 LabJack Support

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Posted 17 June 2014 - 01:56 PM

Your code looks fine to set EIO0 to output-low (0V) and EIO1 to output-high (3.3V).  We are not familiar with the LJU39RL8, so remove that and use a DMM to measure the voltage on EIO0 or EIO1 versus ground to confirm they are set properly:



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