how to measure the time with keithly 2000

[helaka]

Hi , I am doing same resistance measurements and i need to measure the time as well for every data point. I have tried but have not succeded so far.  Does any one know how to do that? thank you for your time. Helaka


Data Read Multiple.vi:
http://forums.ni.com/ni/attachments/ni/170/349187/1/Data Read Multiple.vi

[Dennis Knutson]

Have you verified in the Keithley programming manual that the instrument can return a timestamp? If the instrument is capable of doing so, you would modify one of the existing functions or add a new function to the driver. Otherwise, when you initiate a measurement, use the Get Date/Time in Seconds for the start time. Then see if there is a function that returns the sample rate of the instrument (or maybe this is something you are setting).

[helaka]

Hi Dennis , Thank you for your answer. I do know what is the delay time, let say I do 150 measurements at a delay time of 0.35 s, that means that the total time would be 52.5 s ,but if I measure the time right before and after the measurements it gives me 60.51s . Now my final goal is to fit this data to a given function, if I  divide 60.51s with 150 and find dt for every data point the fitting is mush better than if I use dt=0.35s, but I still have problems and I believe that is because the time measured is not the right one. I am a attaching these programs and hope that some one might  have any suggestion. I did check keithly manual, it does not seem to be a command that says how to measure the time, or may be I am wrong. Helaka


time test.vi:
http://forums.ni.com/ni/attachments/ni/170/349344/1/time test.vi


Data Read Multiple.vi:
http://forums.ni.com/ni/attachments/ni/170/349344/2/Data Read Multiple.vi

[Dennis Knutson]

I think your time calculation is faulty. You are measuring the time it takes for the instrument to acquire and transfer. The transfer time really should not be part of your timestamp. If you want only relative time, just build an array with your dt and starting at 0. If you want absolute time, replace the tick count with Get Date/Time in Seconds. Use that as the first element in the time array with the dt added to each element.