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Immediately source at configured compliance?

Models 2400, 2401, 2410, 2420, 2425, 2430, 2440, 6430
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ddffnn
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Joined: January 12th, 2012, 2:26 pm
Country: United States

Immediately source at configured compliance?

Post by ddffnn » January 12th, 2012, 2:36 pm

I'm trying to use a 2400 with LabVIEW to source 5V with 0.5A compliance, but I'm finding that it uses the default compliance of 105uA until I take a measurement. I take measurements at other times during testing, but I don't need one in this instance. Sure, I can take the measurement just to get the compliance right, but I shouldn't have to. Is this a bug in the LabVIEW driver or the firmware or something?

See attached vi snippet for more info:
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keithley troubleshoot.png
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Kenneth P
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Re: Immediately source at configured compliance?

Post by Kenneth P » January 12th, 2012, 3:28 pm

Hi,

I checked the 2400 LabVIEW vi for setting level and compliance. Additionally, I also duplicated the routine as you have shown. My experiment indicated that the compliance setting changed after the command to set compliance was sent to the 2400. Both the meter, and driver check out OK. I am using firmware version C32.

ddffnn
Posts: 3
Joined: January 12th, 2012, 2:26 pm
Country: United States

Re: Immediately source at configured compliance?

Post by ddffnn » January 13th, 2012, 7:47 am

I've done this on two 2400s now, one with C17 firmware, the other with C32 firmware. I've also attached slightly different labview code that makes it easier to observe the issue. I use an external dmm to measure the current before I actually push a button on my labview front panel to tell the 2400 to measure the current.

Also in the attachment is the version of the 24XX labview drivers I've been using. To

Nathan S
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Re: Immediately source at configured compliance?

Post by Nathan S » January 13th, 2012, 8:36 am

It sounds like you are hitting range compliance then. I haven't run the specific program, but on the 2400 there are two types of compliance, range and source. The source is the standard one that you are setting to a higher level. However, after setting that you should change your current measure range (even if you are not reading those measurements) to the 1A range. On a normal reset, the unit is on the 100uA measure range which will allow a maximum of 105uA to go through even if you change your source compliance. Note on the front panel of the instrument you can verify this is happening by checking the lower right hand corner of the display. If the Cmpl is flashing, that is source compliance; if the current unit -- likely A in your case -- is flashing, you are in range compliance.

ddffnn
Posts: 3
Joined: January 12th, 2012, 2:26 pm
Country: United States

Re: Immediately source at configured compliance?

Post by ddffnn » January 16th, 2012, 7:46 am

Thanks Nathan, you're statements are exactly right. The unit (A) was flashing until I took the measurement. By using the configure measurement vi and manually setting the range to 1A, the problem was fixed. As soon as I enable the output, the SMU sources the full 5V, driving a current of 70mA.

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