PCI-5112 Simulation and Calibration

[AFolly]

Hello,

I am working in a lab where they are using the PCI-5112:

http://www.ni.com/pdf/manuals/373495b.pdf

I had a few questions.

First, I would like to simulate this device on my computer using NI-DAQmx so I can play around with a program which we have on another computer with the actual hardware. However it is not included in the list when I try! Is there a way to "import" the PCI-5112 so that I can simulate it? If not, is there a similar device which someone recommends?

Also while reading the spec for PCI-5112 I saw this:

Calibrated Vertical Ranges; ±25 mV to ±25 V in 10% steps

Just to make sure, this means:

±25mV, 27.5mV, 30.25mV, 33.275mV, etc...

Or does it mean:

±25mV, 27.5mV, 30mV, 32.5mV...etc...

As well, if I select a voltage range outside of these values, is it completed uncalibrated? Or does it round my input to the near calibrated range?

I assume the same answers to the above question also apply to the Calibrated Offset Range? 

Finally, I saw that the internal source should be calibrated to an external source every year, and the self-calibration every 24 hours. I know for certain my lab doesn't do the self-calibration every 24 hours, and I assume they have never done it to an external source. With our experiments however we are just concerned with measuring the decay of an exponential signal. Therefore, would calibration be a moot point?

Thanks in advance for your help and sorry for the multitude of questions!

Cheers

[AFolly]

Strange. When I check the preset ranges in NI-SCOPE on the computer with the NI-5112 it shows:

6.2mV, 10mV, 20mV, 50mV, 0.1V, 0.2V, 1V, 2V, 5V, and 6.2V

When I check in the options I see that the range is indeed set to -10V/10V

[AFolly]

Found a solution to the one question, however doesn't explain why the scope has different values and doesn't go up till -10/+10.

http://digital.ni.com/public.nsf/allkb/38F18D418E2433ED8625690E006BBE94

[DFGray]

The 5112 is a very old device and the driver is written using tradition DAQ, not DAQmx.  This is why you cannot simulate it using DAQmx like you can most high speed digitizers.  You can simulate it by using the correct options in the Initialize with options VI instead of the simple Initialize VI.  I believe they are the default option string (it has been almost a decade since I did this).  If you try this and have problems, let us know and I can dig up the exact string.

The 5112 does indeed have 10% increments in the voltage range setting.  The exact values vary slightly from device to device.  On the 5112, you should set the range to your anticipated need and the driver will choose the next highest range which matches your request, assuring you of best resolution (the 5112 is an 8-bit device, so this is important).

Self calibration can be done on demand by any user.  You can see an example of how to do this in the example niScope EX Calibrate.vi.

Let us know if you have further questions.  Good luck.

[AFolly]

Thanks for the reply!

It looks like it will be too much of a headache to mess around with VI on my computer with all the different versions and such. More time spent which could be spent programming the new VI. I will just try and steal time in the lab when the experiment isn't in use to do it on the computer itself. However, if I do find I have to simulate I will try what you mentioned. Thank you for your help.

About the calibration... Any idea how that works? I don't mean the procedure, but I mean what is affected if the device isn't calibrated? For example, if I have a 5V sine wave as my input signal. Would it mean I would just get say (in a really bad case) a 4.5V sine wave, but the form of the signal would not be changed? In our case the actual signal would be a sharp pulse followed by an exponential decay (with a slight sinusoidal modulation). Or does it mean something else?

I know the self-calibration is easy to do, but I don't see the point if it hasn't been externally calibrated in say 5 years, and we don't have the neccessary equipment to do the external calibration.

Cheers!

[DFGray · Accepted solution]

If you don't do the external calibration, the values you get from the card will not be as accurate as the spec sheet says they are.  This can effect both the time and voltage values, but time values will be less effected, since the clock uses a quartz oscillator, which is very stable.  Since you are using it to measure decay rates, you should probably be OK.  If you need really accurate timing, you can drive the 5112 from an external clock source that has been calibrated recently.