How to sweep Nanoampere current in Keithley 6220 current source with Labview 8.6?

[PVR Karanth]

I am interfacing Keithley 6220 current source by Labveiw 8.6 through GPIB bus and KUSB 488A. I am using example VI which is provided with Keithley drivers for current sweep. I don’t have any problem in sweeping the current in micro or milliamps. But when try to sweep in nanoampere (even the step level in nanoampere), it shows error message “-222” which stands for “Parameter data out of range”.

Can anybody please help me to resolve this error to sweep in nanoampere (stop level as well as step level in nA). I am herewith attaching the the VI which I am using. Front Panel during run (which shows my controls) and the error message are also been attached.

Thanks in advance

Front panel.doc

KE622x -- Execute Current Sweep Example.vi

[Neil Pate]

If you are struggling to get something to work go back to basics and try and create the most simple example you can think of. Can you set a single nA current at all just using the Set Current Level VI that is in the driver?

I have used the 6220, and although I cannot remember if I went down to nA (I think I did) I also do configure the range before setting the current level. I see the example does this (it sets the range to 2 nA), which is strange then that you are getting it to work in the uA and mA range.

I did not use any of the sweep functions, all my outputs were static so perhaps this is just a limitation of the device (but I doubt it).

 

Edited August 22, 2016 by Neil Pate

[PVR Karanth]

Dear Neil Pate

Thank you Very much for your answer.

When I am trying with Set current vi for single current setting, it works fine. Even the instrument is working well, as I can sweep manually in nano range.....

Here with i am attaching the snapshot of front panel.  Is the front panel parameter adjustments are correct? Is there any changes are required? 

Snap shot of Front Panel.doc

Edited August 23, 2016 by PVR Karanth

[Neil Pate]

The only thing I can suggest is looking at the Error message which suggests the error arises in Set Lin Log. Looking at your sweep params on the FP, are you sure you have this set up right. You have a start level of 0 A, a finish level of 10 uA, a step of 100 nA and 11 steps. One of those parameters is not correct, as your step level needs to be more like 1 uA to get from 0 --> 10 uA in only 11 steps. Perhaps this is the source of the error? 

As I mentioned in my previous post, I have not actually used the sweep functions on the instrument. Your time delay seems quite long so would it not be possible to just do the timing manually in a loop?