Input range for a PXI-6071e in DAQmx

[Knight3]

Hi

I’m not sure if this is the right group to be posting to, so my apologies if I’ve got this wrong.

I’m in the process of converting routines written in Labview 7.1 to 2014, which has also meant upgrading from Traditional DAQ to DAQmx. The old version of NI Max I’ve got is 4.5 and this includes the conversion utility. Executing this successfully converts all channels shown in the Data Neighborhood, and no errors are flagged up. However, looking at the Global channels list it creates, those associated with the PXI-6071e card I use have a red X next to them. Clicking on the ‘test’ button for any of these results in DAQ Assistant giving the same error – the expected limits should be between +/- 10V and I’ve specified 0-20V which is how it was originally set up in Traditional DAQ. The measurements I need to make can be upto 15V so I’m assuming I can only set the 0-20V range via software. Would that be correct?

Thanks

Bruce

[Duffy2007]

Hello Knight3,

from the specification side the card can only measure up to +-10V (Range 20V)

NI 6070E/6071E FamilySpecifications

if you measure +15V, then this value is out of specification, this is the reason why the DAQmx task say only up to +10V is possible.

[Knight3]

Hello Alexander,

Thanks for your reply. I had a quick look at the 6071E spec and it shows a unipolar range of 0-20V as unavailable, so I don't quite understand how in Traditional DAQ I was able to set this up without getting any errors. Since DAQmx only allows +/-10V as the maximum range, I guess I've got to work on ensuring the voltages I'm measuring are either clamped or scaled to +10V, or look at getting another DAQ card that can handle a larger voltage range.

kind regards

Bruce

[Duffy2007]

Hello Knight3,

it could be a mistake of the traditional DAQ, that this driver do not check this setting.

[crossrulz]

I just use a voltage divider to get the voltage less than 10V.  In your case, I would use two 1MOhm resistors to divide by 2.  Then use a DAQmx scale to bump your reading back up (gain if 2).  You can also throw in an op-amp set up as a voltage follower to help out the DAQ (low output impedence helps eliminate ghosting).