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Time Intervals measurements using 2612

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johan.castrillon
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Joined: November 13th, 2013, 8:26 am
Country: Puerto Rico

Time Intervals measurements using 2612

Post by johan.castrillon » November 13th, 2013, 8:52 am

Hi,
I am developing a TSP using the default KE26XX Factory Pulse Script in LabView. It should measure current values given time intervals of 10ms to 10ns. My script is only measuring for intervals of .1s or higher.

Script:
------------------------------------------------------------------------------------------------
smua.reset() --Restore Series 2600 defaults.

points = 10
smua.nvbuffer1.clear()
errorqueue.clear()

mybuffer = smua.makebuffer(points)
smua.measure.count= 10
smua.measure.interval = 0.1

smua.source.func = smua.OUTPUT_DCVOLTS --Select voltage source function.
smua.source.autorangev = smua.AUTORANGE_ON --Set source range to auto.
smua.source.levelv = 0e-3 --Set voltage source to 0mV.
smua.source.limiti = 10e-6 --Set current limit.
smua.measure.autorangei = smua.AUTORANGE_ON --Set current range.
smua.source.output =smua.OUTPUT_ON --Turn on output.

mybuffer.collecttimestamps = 1
mybuffer.timestampresolution = 0.001
mybuffer.appendmode = 1
smua.measure.overlappedi(mybuffer)
waitcomplete()

smua.source.output =smua.OUTPUT_OFF --Turn off output.
printbuffer(1, points, mybuffer.readings, mybuffer.timestamps)
-----------------------------------------------------------------------------------------------------------
How can I improve this script in a way that it allows intervals less than the .1s?

Dale C
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Re: Time Intervals measurements using 2612

Post by Dale C » November 13th, 2013, 10:03 am

Turn off Auto range(select a range). (smuX.measure.autorangeY)
Disable Auto Zero. (smuX.measure.autozero)
Set the source delay to 0.0 (smuX.source.delay)
Please note that the Model 2612 cannot get to the 10nsec level. About 200usec is the fastest.
And these are general ICL commands right out of the reference manual. Check the syntax on all of them.

Andrea C
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Re: Time Intervals measurements using 2612

Post by Andrea C » November 13th, 2013, 5:36 pm

Also set the smuX.measure.nplc = x.x

The nplc defaults to 1.0 which for 60Hz power cycles will be 16.7msec for each measurement.

johan.castrillon
Posts: 3
Joined: November 13th, 2013, 8:26 am
Country: Puerto Rico

Re: Time Intervals measurements using 2612

Post by johan.castrillon » November 20th, 2013, 6:36 am

So basically, if I want to have lower measure intervals I need to use a lower nplc, but it causes that my accuracy will be a poor one. Am I right?

johan.castrillon
Posts: 3
Joined: November 13th, 2013, 8:26 am
Country: Puerto Rico

Re: Time Intervals measurements using 2612

Post by johan.castrillon » January 31st, 2014, 6:24 am

I've been trying to reach the 200usec measuring time without hampering the accuracy of the measurements changing the nplc, without success. Is it possible to reach a lower time without changing at all the accuracy? Or is there another way to heighten the speed besides changing the nplc?

Dale C
Keithley Applications
Keithley Applications
Posts: 2841
Joined: June 10th, 2010, 6:22 am
Country: United States
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Re: Time Intervals measurements using 2612

Post by Dale C » January 31st, 2014, 8:14 am

All the parameters mentioned will affect accuracy and resolution.
There is no way to get 200usec measuring time with a setting of 1PLC.
The PLC must be at least 0.01 (167usec).
And at 0.01 PLC the resolution is only 4 1/3 digits.

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