E series maximum AI voltage range

[Andy_458233]

Hi All

I hope you can answer my questions:

We use E series NI PCI-6031 multifunction DAQ cards. The Analogue inputs are taken up to +15VDC but the datasheet of the card states the input range is +/-10V. If the AI voltage is above 10V it is ignored anyway and not measured.

Will this damage the I/O card?

The only parameter in the datasheet on this issue is as below, does this apply for this case?

Analogue Input

Maximum working voltage..............Each input should remain within +/-11V of ground

These analogue inputs have been giving us some strange readings so I wondered if we have damaged the DAQ card by apply a higher voltage than the spec.

Thanks for you help

Andy

[devchander]

---

These analogue inputs have been giving us some strange readings so I wondered if we have damaged the DAQ card by apply a higher voltage than the spec.

---

What sort of 'strange' values are you observing??

could you tell what voltage you are applying and what voltage you are reading??

Are you getting any error message??

does the device fail the resource test in MAX??

This card has overvoltage protection for AI as mentioned

Overvoltage protection

Powered on .................................±25 V

Powered off.................................±15 V

Through it superficially seems you may have in permissible limits, there is a chance you might have damaged the board

[Andy_458233]

Thanks for your reply

We use 32 of the AI channels for one type of measurement which are all reading as expected.

The other 32 channels can be taken upto +15VDC maximum but are usually kept below +8VDC. We see a varying number of these 32 channels give very similar or identical readings of 0.01V or 0.02 although the value can be up to +4.0V. Sometimes occasionally there are no channels with identical values, other times there are up to about 20 out of 32 channels. In the application we are using, this is unlikely to be the true value. These values move to different channels and changes in value and do not occur every time.

The 32 channels in question are measuring the voltage across a resistor which is between ground and +15VDC.

I'm not 100% sure it is the NI PCI card but I just wanted to check we havent damaged it due to what we have been doing to it.

I thought it may be the software we are using, so i formatted the PC hard drive and reinstalled windows and Visual C++ so it is now running the same software as two other identical machines but it still has this problem.

Thanks for your help

Andy

[Andy_458233]

Just to add to my last reply, the card Passes Self Test and doesn't give an error messages

Thanks

Andy

[devchander]

In that case, the best method would be to feed a known voltage value from a voltage generator/ source and verify if the that particular AI channel reads it accurately

[Tom.]

Hello,

The card's specifications are found here : http://www.ni.com/pdf/manuals/370720c.pdf,

That lists it's AI protection, which has already been mentioned as 25V. Make sure you are selecting the correct voltage reference (RSE etc), and if the measurements are only mV out then make sure it is accurately calibrated.

Hope this helps,

Tom.
NIUK

[Andy_458233]

Thanks for your replies guys, I did try all the obvious stuff when I was first looking at it. After taking the whoel thing apart, it turned out to be the moving probes of the test system shorting on something randomly.

Nevermind thanks for the replies anyway...

Regards

Andy