how to read multiple inputs from single anologue channel and display it on diffrent wavef

[vineetmv]

hi

i am doing a project in which i need to read multiple analogue inputs at different time and display the different input in different waveform graph. i tried using index arrays to show multiple channels together. but its not working, can anyone please help me to solve this.

[MikeS81]

Hi vineetmv,

from where did you read your values? Did you using DAQmx. Can you show the part of code you have right now?

Mike

[vineetmv]

i am attaching the code. the top part of the block using daqmx is used to send pre determined values to the digital port (port 0)of ni daq 6009 with some delay. there are 4 digital values as 1,2,4,8 and it again starts from the first in the loop. the bottom block using daq assistant is to read the analogue input from a single point in the hardware. each time a digital signal is send, then an anlogue input would be read and it is displayed in the waveform chart and in the color ramp. the external hardware is a thermal sensor and the change in temperature is shown using color ramp. when the first digital signal is send, then it should read the analogue input and show in the first waveform graph. when the second digital signal(2) is send, then it should read the anlogue input and show in the second waveform.........but i tried using index array to solve this problem. all the waveform charts are showing the same data simoltaneously instead of first input in the first wave form chart and the second input in the second waveform chart..... can anyone help me to solve this problem.

thanks

vineet

[Prashant M]

Hi Vineet,

I hope you are well.  Thanks very much for this post.  It is quite interesting.  I have taken a look at your code and I noticed that you only have one channel selected in your DAQ Assistant.  This could be why you are only seeing one waveform on all 4 charts.  If you add in more channels so that you have 4 channels in the DAQ Assistant and assign them to the same physical channel then I think that would solve your problem.

Also could you tell me what the Combo Box is for as I would be quite interested.

I hope this helps and please let me know how you get on.

Kind regards,

Prashant M
Applications Engineer
NI UK & Ireland

[vineetmv]

hi

Thanks for the reply. . is there anyway to take multiple inputs through a single channel and show in different graphs. the combo box is not used anywhere. it was a mistake.

can u please help me to build a string or text in the front panel only when particular inputs are selected to show its selection.

thanks

vineet

[Prashant M]

Hi Vineet,

I hope you had a nice Easter. Thanks for your message. 

I have taken another look at your code and what you would like to do and made a few modifications.  In the top part of your code, I have put in a local variable with shift register to indicate the digital signals coming in and I have linked this to your index array. 

In the bottom part of your code, I have added 4 channels in the DAQ Assistant and assigned them to the same physical channel as stated in my previous reply.  I have also added a case structure which the index array is connected to and have assigned cases for all 4 waveforms so that you see the respective waveform(s) being updated and displayed after the 20second preiod that you have set up in the code at the top with respect to the digital signal coming in.  I have attached the code to this reply.

I hope this helps and let me know how you get on.

Thanks very much.

Kind regards,

Prashant M
Applications Engineer
NI UK & Ireland

[vineetmv]

thanks for the reply. the labview version i am using is 8.2. so this program cannot be loaded. is there anyway to hold a particular signal from the hardware untill the next value is attained.

thanks

vineet

[Prashant M]

Hi Vineet,

Sorry about that.  I have converted the file compatible for LV 8.2, so the attached file should run on your machine now.  Hope this helps.

Let me know how you get on.

Thanks.

Kind regards,

Prashant M
Applications Engineer
NI UK & Ireland

[Ben]

Prashant,

I think you are mis-reading the req's.

The user is trying to implement their own multiplexing (like what happens in SCXI).

Ben

[Prashant M]

Hi there,

Thanks for that, I have had another look at the code and modified it so that I think it does what you want it to do now.

You should see your inputs going through a single channel and shown on different graphs with the Numeric display on your front panel indicating your digital values. 

Sorry about the confusion.

I hope this helps and let me know how you get on.

Kind regards,

Prashant M
Applications Engineer
NI UK & Ireland