Keithley 2000 scan channel sequence always change

[l123173]

Hi,

   I would use Keithley 2000 and scan card for 4w resistance.
   The scan worked well except one question. The channel of output was not same each time. I means the output of channel order was 1,2,3,4,5 (first) and 2,3,4,5,1(second) and 3,4,5,1,2(third).

   It is not good for the data processing for the large number of data. Does anyone could give me some help?

Thank you

[Albert.Geven]

You should move the visa open vi before the loop, opening each time is not necessary.

Maybe that helps. part of opening is resetting the instrument and takes a lot of time.

[JÞB · Accepted solution]

 Because at the end of the loop you send a trigger that puts a measurement in the output buffer.  You do't reset the device on the next initialize so on the second iteration you'll already have a value for ch1 then you take five more (2,3,4,5,1) leaving the old 1 in memory, then you ask for a trigger again (ch2 now) that you will never read.  Eventually you are going to overflow that buffer!

get rid of the abort trigger and init trigger you really don't need them at all. (unless you WANT the current behavior and an eventual buffer overflow)  Then move the initialize with options and configure 4wire resistance vis outside the for loop. The case structure around the configure vi is just silly.unless all you want to do is change the TRUE constant to False (there are easier ways to just generate an error) 

[l123173]

Your answer was always useful.

Thank you. I would try it later.