keithley 2400 GPIB read voltage hitting ceiling value

[Runge]

Hi

I have written a very simple program for the Kiethley 2400 (Attached), using GPIB commands. I have not made use of GPIB/VISA functions provided by keithley.

I am sourcing current and measuring voltage(other non-essential paramateres such as time etc may also be read).

The program runs fine , but everytime the voltage reading is '+9.910000E+37', the sample has a resistance of only 50 ohms. So I know for sure there is no open cicuits.

Any hints/suggestions/solutions are welcome. If this query has been posted by some one else, do guide me to the same

FYI : When I use the VISA module I can overcome this problem, but the issue is the time consumed when using the VISA modules

[cymrieg]

Runge, Not sure what you mean by the VISA modules? Do you mean the VXIPnP driver or the native LabVIEW driver on the Keithley web site? You should look at the native LV one and see what commands it is sending which your code is obviuosly not.

[Albert.Geven]

What does the instrument frontpanel say about the voltage?

And did you really enable reading of the voltage?

[Runge]

Hi Cymnreig

Those are Labview drivers from Keithley's website

I am stripping those apart to see where I am making a mistake

Hi Albert

The front panel shows the current. I am not sure how to make it display voltage

When u refer to"enabling the voltage " are u sugesting that other than the "FORMat" comand, There is another command required to enable it.

Thanks

[xdaf · Accepted solution]

Hi,

in order to enable voltage reading, you should use :CONF:VOLT (but maybe it's the default setting...)

In order to transfer the last buffered reading from KE2400 to PC, you should use FETC instead of READ (READ is the combination of INIT and FETC)

[siva0182]

I have attached a vi to source current and measure voltage.The vi works but I am trying to speed up the measurement .

I have disabled display,set sourcedelay and trigger delay to 0.0001 sec set average off nplc to 0.01 and auto range off but  i am able to get only one reading every 9 msec.

I am measuring 0.1 mA and measuring voltage of 0.5 V 

The specification of the keithley 2400 model is 1700 readings per sec at 41/2 digits via GPIB cable.

What else can be done to increase the speed?

[Runge]

Hi xdaf,

Your commands  work provided voltage is the only parameter which is read out.

But who is complaining. Its good enough for my application

Runge

[Mathan]

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Runge wrote:

Hi xdaf,

Your commands  work provided voltage is the only parameter which is read out.

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Then please mark xdaf post as solution to your problem, rather than marking your own post. Hope you know how to unmark and mark the correct one again.

Thanks,

Mathan