From 11:00 PM CDT Friday, Nov 8 - 2:30 PM CDT Saturday, Nov 9, ni.com will undergo system upgrades that may result in temporary service interruption.

We appreciate your patience as we improve our online experience.

LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

Data acquisition 20Ks with time stamp

Solved!
Go to solution

Hi, Please I need help! I need to do data acquisition with 20 KHz and I would like to save these data with time stamp for each sample. I have used the myRio 1900 do it.  In my code below I have tried to read only one analog channel but after the fix my issue I will need to read two analog channel. According diagram below for each exectuion I received array with 1000 data but when I save the data in TDMS format I have only one time stamp for each exectuion.

For example the lenght date & time is 120 and the voltage is 120000.

 

LVelozo_1-1679592504843.png

 

 

LVelozo_0-1679592449451.png

 

0 Kudos
Message 1 of 13
(1,907 Views)
Solution
Accepted by topic author LVelozo

Hi LVelozo,

 


@LVelozo wrote:

when I save the data in TDMS format I have only one time stamp for each exectuion.


Convert your signals to waveforms, which contain t0 and dt. Then save those waveforms to TDMS.

Then you can easily recover a timestamp for each sample…

 

(Does myRIO allow to read waveforms directly in the same way as DAQmx?)

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
0 Kudos
Message 2 of 13
(1,892 Views)
Solution
Accepted by topic author LVelozo

I don't think that myRIO has a DAQmx timing engine to store the t0. You can implement your own t0 engine. 

The inspiration is from NI CompactRIO Waveform Reference Library

ZYOng_0-1679600285461.png

 

 

-------------------------------------------------------
Control Lead | Intelline Inc
0 Kudos
Message 3 of 13
(1,881 Views)

Hi GerdW, first I appreciated a lot your help. Please could you share with me the example how can I recover a timestamp for each sample ? I would like to have a file with two columns one time stamp and second column with data. 

0 Kudos
Message 4 of 13
(1,853 Views)

Hi ZYOng, first I appreciated a lot your help. In the example I have one column with the data, is it possible to have two collumns in the file ? I would like to have a file with two columns one time stamp and second column with data for each sample.

0 Kudos
Message 5 of 13
(1,852 Views)
Solution
Accepted by topic author LVelozo

On the waveform manipulation pallet you will find a vi that takes in a waveform and returns an array of timestamps calculated from t0, dt and size of y[].  Of course, it is trivial to write yourself.  Just auto index a for loop over y, and output t0 + i * dt to an indexing output tunnel.  If you really can't find it in your heart to use a wfm instance of DAQmx read, use timestamp + i / sample rate.


"Should be" isn't "Is" -Jay
0 Kudos
Message 6 of 13
(1,838 Views)
Solution
Accepted by topic author LVelozo

Use a while loop to generate an array of increasing timestamps and write it to a different channel.

ZYOng_0-1679627485343.png

 

-------------------------------------------------------
Control Lead | Intelline Inc
0 Kudos
Message 7 of 13
(1,824 Views)

Hi team, please I would like your help. I am not familiar with myRIO 1900 and I need to do data acquisition from two analog input with 20KHz and 10.000 samples with time stamp. The code below working good for one analog input I have the data record in file with time stamp, but I don`t know how to insert the second analog input. If I insert two analog input in the array connected to Smart Open.vi I had a error. 

 

LVelozo_0-1679681846714.png

 

   

 

 

LVelozo_2-1679681573913.png

LVelozo_3-1679681697928.png

 

 

 

0 Kudos
Message 8 of 13
(1,793 Views)

Hi L,

 


@LVelozo wrote:

I don`t know how to insert the second analog input. If I insert two analog input in the array connected to Smart Open.vi I had a error. 


Which error did you encounter?

Best regards,
GerdW


using LV2016/2019/2021 on Win10/11+cRIO, TestStand2016/2019
0 Kudos
Message 9 of 13
(1,784 Views)

LVelozo_0-1679682436778.png

LVelozo_1-1679682467684.png

 

0 Kudos
Message 10 of 13
(1,777 Views)