LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

keithley 2400 scheduled acquisition

Greetings,

      I'm new to LabView (as in greener than green).  We already have a vi that acquires I-V data from a Keithley 2400 and outputs these data as text files on a per run basis.  I'm wondering if there is a way to configure the existing vi to acquire data on a schedule?  I'd like not to have to come into my lab every 4 hours just to hit a button 🙂  Does anyone have any advice?  Thanks!

0 Kudos
Message 1 of 4
(2,375 Views)
The preparation video for the CLD exam covers different timing techniques if you have the time. There are several ways to accomplish what you want to do. One quick and crude method is to use the elapsed time express vi along with a case structure.
0 Kudos
Message 2 of 4
(2,366 Views)

Hi Bob,

 

There are a few ways to do this, but the way that I would suggest is to use the Elapsed Time VI inside the case structure. Just set the start time at 0 seconds and count up to 14400 seconds (4 hours). Then wire the time 'Timed has Elapsed' boolean output to a case structure that does whatever function you need every 4 hours.  Also make sure you wire a true constant to AutoReset.

 

Regards, 

National Instruments
RIO Embedded Hardware PSE

CompactRIO Developers Guide
0 Kudos
Message 3 of 4
(2,336 Views)

I prefer to use the Time of Day functions for long time like that. Set the start time into a shift register.  Once per second check if current time is greater than or equal to start time.  If True, set a new start time and do the acquisition, else wait a second and check again.

 

This method does not require you to compensate for the time it takes your acquisition to run.  In this regard the method I described above starts at a specified time of day rather than after a specified delay.  The Elapsed Time VI does use the time of day internally but does not have an option for a target time rather than elapsed time.

 

By saving the next start time to a file, the system could be set up to resume testing after a power failure.

 

Lynn 

0 Kudos
Message 4 of 4
(2,331 Views)