how to send a voltage value from labview to Keithley 2400 source meter

[hamlam]

Hi everyone,

I just want to use Labview to send 7 (arbitrary number) volts to heat up a heater connected to the Keithley but it's not working. I have zero to no experience with Labview so I'd greatly appreciate your help..........................

I am using an RS232 to USB to connect the Keithley to my laptop. I opened NI-MAX to use the test panel and sent the command "SOUR:VOLT 7\n" and got Vsrc to say 7V but I looked at my multimeter and nothing is actually being outputted. I also made a Labview code but I get the error "

Error -1073807346 occurred at VISA Open in test.vi".

Please see the attached images. 

Thank you,

Hannah

[altenbach]

If somebody attaches 25MB (!) of blurry  high resolution photographs of a computer screen to illustrate a problem that is worth a few hundred bytes we can assume that the poster is not very computer literate.

Please take simple screenshots cropped to the interesting part and embed them in the post. You also seem to be using LabVIEW, so attach your VI too.

[Minions]

First off, your meter measurement is done incorrectly.  You have the meter set to measure AC Voltage and NOT DC Volts.  Set it to the V-- option for DC Volts.  It should show around 6.4Vdc.

Next, the reason why the Keithley 2400 may only be driving 6.4166V instead of 7V is possibly due to foldback of the supply with the current limit set to 105uA (See compliance).  Set the current compliance to 1mA which should allow the Keithley to provide the full 7V.

Lastly, the IMG_8039.jpg image with the SCPI command:

4:  Write Operation (SOUR:VOLT\s7\n)

shown for setting the voltage does not drive a response.  The read response from 5: is from an earlier *idn?\n query that was only written to the instrument prior to the voltage setting.  What is the issue or reason for this image that may confuse someone if they are unaware of what must have occurred?  

[cstorey]

Follow Minions' advice to achieve an accurate current reading. To get your reading into your LabVIEW code you will need to read the programming manual and look at the right SCPI commands (FORMat & FETCh) to retrieve your reading.  The manual has lots of good examples for many common measurements.  

But, since you don't seem to have experience with SCPI or the SMU you should consider using the "driver" code available from NI for the Keithley 2400 - https://sine.ni.com/apps/utf8/niid_web_display.model_page?p_model_id=1583

If you unzip that and inspect the examples you will find how to source and measure.  Then you can use those examples to build your own program. There are likely dozens of example programs available on this forum that might suit your needs if you search them out.

But do read the manual as SMUs have lots of features you should learn to use to your advantage!

Craig