acquiring data at fast through 6514 electrometer

[charnu257]

I have been working with Keithley Electrometer 6514 to acquire the current values using GPIB (KUSB 488B), and for that, I made a simple program using available drives and pellets. but I am able to get only 3 to 4 data points in a second, how can I increase the data acquisition speed? the VI made by me is attached here.

[GerdW]

Hi charnu,

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@charnu257 wrote:

I have been working with Keithley Electrometer 6514 to acquire the current values using GPIB (KUSB 488B), and for that, I made a simple program using available drives and pellets. but I am able to get only 3 to 4 data points in a second, how can I increase the data acquisition speed?

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Read the manual of your device to learn about its specs and about its programming interface.

With both you can try to increase the sample rate…

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@charnu257 wrote:

the VI made by me is attached here.

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Nope.

[charnu257]

Thanks for your reply. here is the VI

[GerdW]

Hi charnu,

a simple way to improve iteration speed would be to move as many init functions as possible out of the loop…

[Henrik_Volkers]

Have a look at the manual.  (or RTFM in short 😄 )

By defining NPLC (default 6 or 5 , depending on power line freq)  and filter settings and if you use autorange or not , you will get different reading rates. Faster readings , lower resolution/acccuracy, that the deal as always 😉

And have a look at the producer consumer architecture if your software is the bottleneck

[santo_13]

In short, to improve the speed, move all one-time configurations outside the loop, especially the ones highlighted below.

As Henrik guided, read the manual to see if there is special technique recommended to get the utmost performance from the instrument.

[charnu257]

Thanks for your reply, I already tried moving all the configuration pellets out of the loop but it didn't help much. Please suggest any other way of doing it. Thank you.

[cstorey]

What is the range of your current reading? (fA, nA, mA??) 

Electrometers are typically used for very low charge (i.e low current, low voltage) measurements where you have either extremely high capacitance or resistances.  This low charge "counting" process is not instantaneous and the noise is only improved with averaging.  I usually expect 1 measurement per second when measuring ~1pA.  So the 2-3 measurements a second seems normal.   

If you need high speed measurements perhaps look at using a scope with a current probe or an SMU.

Craig

[santo_13]

As per the instrument manual, you can leverage the 2000 measurement buffer to sample at the fastest rate.

[charnu257]

Thank you all for your replies, I will try to figure it out now with your important suggestions. If anyone wants to add something, it will be a great help. thank you.