how to read the gain list of a DAQ card from labview?

[Vsh]

Hi,

Its known that you can set the gain of an ADC of a DAQ card by setting the high and low values.

Different cards have got different signal ranges corresponding to different gains.

My question is ... Is it possible to read the gain list of a DAQ card from labview?

It is definitely possible to read the signal ranges available for the device. It would be very helpful if some one can tell me the method to read the gains corresponding to the signal ranges.

(Even the device specification provides only the signal range but not the gain corrsponding to it )

Thanks

Message Edited by Vsh on 04-08-2008 03:50 AM

[Mathan]

Hai,

Could you provide some more details like which particular DAQ card you are using.

Thanks,

Mathan

[Vsh]

I am using different DAQ cards. both E series and M series

For example let say for time being you can consider as PXI - 6251, an M series board

[Vsh]

The idea behind knowing this is, An M series(PXI 6251) has a gain of 1 for its full scale range(-10 to 10).

But an E series (PCI 6030E) has a gain of 0.5 for its full scale range(-10 to 10)

[Neal M]

Hi Vsh,

It appears that you have found the gains applied for the various ranges (I assume from the user manuals).  So if I understand your question correctly, you are looking to poll the card for the current gain (or the various gains available)

Because DAQmx selects this for you (unlike Traditional DAQ), there is not a way to poll directly. If you want, you could poll the min/max values and then use this to figure out the range setting (and thus the gain).

Please refer to this post, it gives more information about the gains/ranges in general.

I would suggest putting in a product suggestion if you would like this feature.  Those go into the decision making process for our R&D team, meaning they actually do look at them.  If you wish, I can submit a suggestion internally was well for you, that way your suggestion gets 2x the exposure.  Let me know if you want me to do this.

[Vsh]

Hi Neal,

like you said,
I was wishing to have a list of gains that are set in DAQ card corresponding to the High limit and low limit. Since it is not available, an option for polling the gain for full scale range also would have been helpful so that I can calculate myself the rest of the gains based on the high and low limits.

---

@Neal M wrote:
I would suggest putting in a product suggestion if you would like this feature.  Those go into the decision making process for our R&D team, meaning they actually do look at them.  If you wish, I can submit a suggestion internally was well for you, that way your suggestion gets 2x the exposure.  Let me know if you want me to do this.

---

I would be very much pleased if you can do this.

And yes, I found it in user manuals, but no information regarding the same in the device specifications.

Thank you for your concern.
 

[Vsh]

Sorry,

I did not get it from the user manuals, I got it from searching through the NI website. Can you tell me which user manual you are talkng about?


Message Edited by Vsh on 04-09-2008 05:45 PM

[Neal M]

Hi Vsh,

I got the E series gains from the E Series User Manual (starting on page 2-3).  I happened to know the M series off the top of my head.  I dont think that they are in the user manual because you dont need to program them like in Traditional DAQ (which the E series can use). In DAQmx it all is taken care of in the driver.

[Neal M]

P.S.- I went ahead and submitted that product suggestion for you.

[stilly32]

One thing to remember about gain and the ADCs - scaling for the M-Series is not linear it is a polynomial, so if you are reading binary values and trying to use the gain to calculate the voltages you're going to get incorrectly scaled data. This may not be a concern, but I thought I'd bring it up.

cheers,
Andrew S.