Multiple channel measurement

[LB_Vladi]

Hey guys, i am relativly new to Labview. I did a lot of the beginners Tutorials but i am stucked with my VI.

At the moment i simulate the Signals of the NI USB-6289.

Basically i want to measure 24 Voltage Inputs with the NI USB-6289 at the same time on 12 diffrent Positions and write it into Arrays.

Each of the Values must get a diffrent Offset and Factor.

I also want to control when to measure ( with a button " next measurement" or something like that ) and  in which Array the next measurement will be written.

Furthermore i woud like to have a boolean wich on the true case automaticly go to the next postion when i  click on "next measurement" and on the false state it stays on the position i have choose. How coud i implement this function in my VI ?

This is my current VI ( see Attachments).  I`ve been told that this can be done much easier since my Block Diagram is allready so big. And that I have a Race Condition.

And now i have no Idea how i can give every single channal diffrent Offsets and Factors with an easier VI and how i can get rid of the Race Condition. 😞

Can someone help me

best Regards

LV_Vladi

[Jon_15]

Hey,

die Offset and Factor can be set with the custom Scale:

What Are Custom Scales and How Do I Use Them? - National Instruments
http://digital.ni.com/public.nsf/allkb/0464919A11C092E386256D800079C3BB

How Do I Programmatically Create NI-DAQmx Custom Scales in LabVIEW? - National Instruments
http://digital.ni.com/public.nsf/allkb/F7DAE47B4408A86F8625765700767FCD

The custom scales can be sored in a array.

Check out this:

Community: Create Custom Linear Scale for Each AI Channel in LabVIEW Using DAQmx - National Instruments
https://decibel.ni.com/content/docs/DOC-11136

Is it needed to change the position to write?

Otherways you just can write the measured data in a 2-D Array and each column represents one measurement.

[LB_Vladi]

Hey Jon thanks for your help. I will read your Links and try to implement them.

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@Jon_15 wrote:

Is it needed to change the position to write?

Otherways you just can write the measured data in a 2-D Array and each column represents one measurement.

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Normaly it is needed to change the Position to write.

But for the first Try it woud be enough without this function.

Will it work with the DAQ Assistent ? or do i have to start new and build the VI with the DAQ Functions ?

[Jon_15]

you can use the DAQ Assistant and set the custom scale for each channel.

to get a better view of the tast you can convert the Assistant to DAQmx tasks:

Using the DAQ Assistant to Automatically Generate LabVIEW Code - National Instruments
http://www.ni.com/tutorial/4656/en/#toc8

[LB_Vladi]

Hey Guys,

Why do i always get this Error if i try to Custom Scale my values ? ( see attachment ) .

Do i missunderstand the Custom Scale ?

I mean i want to be able to measure volts from -1V to 1V but display them as a Numbers from -1000 to 1000 or  -3000 to 3000 whatever my scaling is.

I thought i coud do it with the linear Scale 😞

[crossrulz]

The value you use for the Maximum and Minimum when you set up a channel need to be based on the values AFTER the scale has been applied.  It looks to me that your current scale is just a positive offset of 5.  Therefore your max and min need to be within the -5V and +15V.

[LB_Vladi]

Hey Crossrulez,

Thansk for the help. I Understand the error but it means i cant use the custom scales for my purpose or ?

Or How can i dispay my measured values like i want ?

For example if i measure 1V  i want to multiply it by 100 and add 15 to it so on the Front Panel i see a 115 value.

mfg

Vladi

[crossrulz]

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@LB_Vladi wrote:

Hey Crossrulez,

Thansk for the help. I Understand the error but it means i cant use the custom scales for my purpose or ?

Or How can i dispay my measured values like i want ?

For example if i measure 1V  i want to multiply it by 100 and add 15 to it so on the Front Panel i see a 115 value.

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I'm not understanding your problem.  If you apply a DAQmx scale to a channel, then when you do a DAQmx Read, it will return the value after the scale.

[LB_Vladi]

Hey Crossrulez,

Did you checked my VI on my first post ? I have there 24 Channels. And I add and multiplay a number to each channel so i can display the measured values like i want.

But i was told that there is a way to do this much easier and better for example with this custom scales. But i only get Errors if change The Values in the custom scales :/.

Sorry i am a beginner ^^.

[crossrulz]

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LB_Vladi wrote:

But i was told that there is a way to do this much easier and better for example with this custom scales. But i only get Errors if change The Values in the custom scales :/.

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Then you should show what you tried and say exactly what your scale is.  In this example, I made a scale that just had a gain of 1000 and offset of 0.  I then had to change my range to match my scale: -10k to 10k.  The value that is then passed out is the value after the scale is applied.  It is that simple.