extend the display time in DAQ for more than 10 sec

[smoothengine007]

I create a analog DAQ vi. Everything works fine. However, no matter what I increase the sampling # and rate; the maximum display time is always 10 sec. I need to display longer period time, but don't know how. Can anyone help?

[RavensFan]

Display time where?  A waveform graph or chart?

A waveform chart has a default history of 1024 points which can be changed.

The other possibility is that depending on your sampling rate and # of samples (please give some examples as to what numbers you want to use) is that the # of samples if more than 10 times the sampling rate would take longer than 10 seconds, and you are hitting the default timeout for a DAQ read.

Please post your code with and values that you are setting in controls saved as defaults before uploading the VI.

[smoothengine007]

It is the display time in the waveform graph.

 I used the sampling rate at 1k Hz, and the number of samples is 10000. I played around with this 2 parameters, and didn't increase the time scale. It did shorten the time scale if lower the sampling rate.

I have another vi to feed in the box-car signal (1 sec on and 2 sec off), and this signal will continue for a few minutes. I am measuring  the other signal (UV) throughout this period. I don't have to display the full length of it, but at least I can display 20 to 30 sec in any period that it is acquiring the data.

I hope this explanation will help you understand what I'm doing.  I attached the vi. Thank you and I appreciate all you help.

[RavensFan · Accepted solution]

Not a good VI.  Where did you get it from?

The VI properties/execution had the check box next to Autmatic Error handling unchecked.  And you don't have an error indicator on your DAQ assistant or any error wires at all.  Fix them and I bet you will see you are getting a timeout error.  Also the while loop had Autogrow unchecked which meant adding constants or changing the view of the Express VI's caused them to disappear outside of the loop rather than growing to accomodate them.

You don't have a timeout constant wired to the DAQ assistant, which means it will use its default of 10 seconds.  This will cause a timeout error which you won't see because that VI property is unchecked and you don't have any other error handling in its place.