Difference between Voltages in time frames!

[aarief]

Hello,

I am working on LabVIEW for analysis on temparature measurements.  Can anyone help me out-- how to find the difference between two voltage values in two time frames?  I get continuous values of varying voltage from USB module(ez430 RF2500) every second, for example, at time t0 -- 0.415V , at t1 --  0.425V, ......continuous...i want to display the difference between the amplitudes between two time frames continuously (present and previous) in a waveform chart!  Can anyone suggest any method/VI for above!?

Thanks in advance!

[srikrishnaNF]

Hi aarief,

 Can you post your VI for continuos acquisition of data with samples for every one second?

Thanks and regards,

srikrishnaNF

[aarief]

Hello Krishna,.

I have designed the VI for normal single read of buffer string, but i run the VI in continuous mode, the USB module sends data to Labview via VISA Open nd VISA  Read and i have done few modifications on strings to get the values. As i need the differences in values to be displayed, i am trying using converting into array thn array functions,then finding difference. Do you have any idea how to find out the difference?

I run the VI in Continuous mode to read the buffer continuously!

[srikrishnaNF]

Hi aarief,

  Since you are acquiring data at the rate of 9600bps...so for a second you will acquire 9600 bits means 800 floating values.....if you acquire a value A,then after 800 values ,if your acquired value is B..then you need B-A ..isn't?

Thanks and regards,

srikrishnaNF

[aarief]

Hi krishna,

Yes, That will be one difference value, as i get continuous data buffers till i keep VISA Read running,i want to have difference between consecutive values (present nd previous) continuously to display the differences in a waveform chart

Thank You,

Aarief Hussain

[srikrishnaNF]

Hi aarief,

  For that as you use a while loop for continuos acquisition...place a shift register and initialize with zero...and now read the value from read function and substract the value from the left...Just check the attachment..

Thanks and regards,

srikrishnaNF

[aarief]

Hello Vamsi,

Im new to LabVIEW (learning),

What is the function you have used for string to DBL?

Can you forward me the VI?

Regards,

Aarief

[aarief]

Hi Krishna,,

I got the function(scan from string),, i have to implement in the VI..

Thanks alot! I guess this will work!

Regards,

Aarief.