Applying formula to two columns of data

[Michael Collins]

Hi,

I've started to use DIAdem and it appears very powerful.  Comparision between different data channels

is straightforward and the built in functions are useful.  What I'm comparing with with the older way I

analysed data within EXCEL.  To deduce INL and DNL from raw data of a DAC.  See attached how the

formula has been applied to some dummy data I made up of a 3 bit DAC!  Anyhow I'm wondering if there

is a correspondingly easy way to implement this formula in DIAdem.  Any help appreciated.  I'm played

around with the calculator a little but to no avail.

Thanks,

Mike

[Brad_Turpin]

Hi Mike,

What version of DIAdem are you using?  If it's 11.x or later then I'd recommend you try the Calculation Manager, which is much easier to use than the Channel Calculator, and it's also much easier to re-use expressions you've created.  Exercise 6 of the free downloadable DIAdem Hands-On Exercises shows an example of this starting at about step 30:

http://zone.ni.com/devzone/cda/epd/p/id/5393

If you're stuck with an earlier DIAdem version, we can get the Channel Calculator to work for you.  Let me know and I'll try to set you on your way with the best technology available.

Brad Turpin

DIAdem Product Support Engineer,

National Instruments

[Michael Collins]

Hi Brad,

I'm using version 11.2 so I do have the Calculation Manager which I've used in a similar way to

that in the exercise document you've forwarded.  Good document BTW.  However what I wish to

do is a little more complex than just addition of the square of elements etc.  As per the EXCEL

file I'm looking to perform an calculation on Element (i) and Element (i-1) for all i (the length of

the array) etc. 

Again an example of this would be appreciated.

Regards,

Mike

[Otmar]

Michael,

I took your Excel file and tried to recreate the exact same thing in DIAdem 2010.

Here's what I did:

The Excel function that subtracts values within a column from each other can be replaced by the "Calculate Differences" function in DIAdem ANALYSIS (ANALYSIS > Basic Mathematics > Calculate Differences). That creates a new Channel I called "Delta" in my DIAdem Data Portal.

The next thing I did was add the LSB value as a property to a data channel (in my case I added it to "Readings" as a custom property).

The next step was to go to ANALYSIS and select the Calculation Manager from the toolbar. I added two calculations to the calculation manager, one for DNL and one for INL.

And here is the INL calculation:

That's what got me the same results you have in Excel ...

Ask if you have further questions,

      Otmar

[Brad_Turpin]

OK Mike,

I'll take a closer look at the Excel file and get back to you.  What you describe is possible and quite efficient in DIAdem.  I'll provide an example.

Brad Turpin

DIAdem Product Support Engineer
National Instruments

[Michael Collins]

Thank you Otmar,

That looks pretty straightforward.  Did you also calculation for the LSB from the readings,

and similarly for the Ideal Readings from this.  I'm still trying to perform these step.  The

calculate difference function is useful.

Thanks,

Mike

[Brad_Turpin]

Hi Michael,

Otmar sent me his Calculation Manager files before he went home for the day in Germany.  I created a quick VBScript that loads the data from a TDMS file, calculates the Span and LSB properties and the Delta channel and then runs both Calculations.  Give this a try, then we should probably chat about how easiest to import your data into DIAdem.  Does your data start in Excel or does it start in an ASCII file that you load into Excel?

Brad Turpin

DIAdem Product Support Engineer

National Instruments

[Michael Collins]

Hi Brad,

Thanks for that.  My data would come from a DMM, into LV and save as a .dat or csv file.  I think open

within EXCEL and perform my analysis there.  You solution works for me.  However developing a script

for each function may be an overhead initially.  If we could have a chat about this I'd appreciate it.  Let

mw know a number to call and a suitable time.  I'm free today after 2.30pm (Irish time).

Thanks,

Mike

[Brad_Turpin]

Hi Michael,

What type of *.dat file do you mean?  Is it binary?  Is it the old DIAdem-DAT file format?  Regardless, the best solution would be to have a DataPlugin available for each file format you use so that import into DIAdem is easy.  We already have a DataPlugin for the old DIAdem-DAT file format, which installs automatically with DIAdem.

Send me an email and we can arrange a time to talk-- brad.turpin@ni.com

Brad Turpin

DIAdem Product Support Engineer

National Instruments