measurement problem in Keithley 2635

[yuxj]

hi, all

I use a Keithley 2636A to do measurement only, that is direct measure voltage or current. Input connected to channel A

My question:

   when I changed measurement from voltage to current, or versa vice,  in first few readings, are just same as that of previous measurement (for examples, If I switched measurement from voltage to current, in the first few readings, I still got the voltage data, and later on, I could get the correct current readings.). Because I did not use buffer to store data, why the data still buffered? I use print(smua.measure.i()) or print(smua.measure.v()) to read the current or voltage directly.

In the each measurement beginning and end, I had issued a command smua.reset() to reset the instrument, respectively.

Anyone any suggestion would be appreciate.

-yuxj

[KateB]

If you use C to program your Keithley, you probably contact Keithley, http://www.keithley.com/support, directly, but if you use LabVIEW, could you please attach your code, and 2636a command set so that we can further assist you to analyze the problem?

[yuxj]

Thanks! I use labview.

command sent to 2636 for voltage measurement

--------------------------

;initialize the 2636 in the measurement beginning

localnode.prompts=0
reset()
smua.measure.nplc = 1

smua.source.func = smua.OUTPUT_DCAMPS
smua.source.leveli = 0.00000E-9       

smua.source.limitv = 20 
smua.measure.rangev = 20
display.smua.measure.func = display.MEASURE_DCVOLTS

display.screen =display.smua

format.data = format.ASCII

smua.source.output = smua.OUTPUT_ON

;measure loop cycle, to read the data in some tie delay

print(smua.measure.v())

;when the measurement finished

smua.source.output = smua.OUTPUT_OFF

smua.reset()

command sent to 2636 for current measurement

--------------------------

;initialize the 2636 in the measurement beginning

localnode.prompts=0
reset()
smua.measure.nplc = 1

smua.source.func = smua.OUTPUT_DCVOLTS

smua.source.levelv = 000.000E-3       

smua.source.limiti = 2E-3 
smua.measure.autorangei = smua.AUTORANGE_ON
display.smua.measure.func = display.MEASURE_DCAMPS

display.screen =display.smua

format.data = format.ASCII

smua.source.output = smua.OUTPUT_ON

;measure loop cycle, to read the data in some tie delay

print(smua.measure.i())

;when the measurement finished

smua.source.output = smua.OUTPUT_OFF

smua.reset()

[KateB]

This is C code.

Not LabVIEW.

[yuxj]

These are ascii command sent to 2635 in labview program, but how to post labview program code?  it is some graphic block.

The labview prorgram runs normal, but the a few data readings are not correct in a new measurement.

[KateB]

attach the file.