keithley 2000 current measurement

[Pradeep_Bejugam]

Hi All,

I am using keithley 2000 DMM to measure current. I have configured the DMM under IVI Drivers in MAX. I am using the example program in CVI to configure and read the current drawn. When I read the current drawn from the DMM the current value displayed is incorrect. I have used the auto adjust to zero function also. Even on multiple readings with delay, the value keeps fluctuating and is no where near to the expected value. Can anyone suggest why I am not able to read the correct value? Where can I find the configuration parameters for this DMM in MAX? How do I know if I have configured the DMM correctly in MAX or not?

Any pointers would be helpful.

Thanks in Advance,

Pradeep

[Denver_]

Hi Pradeep,

Try downloading the drivers for the Keithley DMM from http://sine.ni.com/apps/utf8/niid_web_display.model_page?p_model_id=248

Nxt question is as to how you are connecting the DMM to your PC (serial, gpib??)

If you have connected over GPIB, verify that it is showing in MAX under devices and interfaces.

You can then right click on the instrument and select communicate with instrument. Use simple commands that should be available in the manual to read data from 

the DMM. Once you have verified that communication is established, try using the example programs in CVI.

Regards,

Denver

AE, NI India

Message Edited by denver_ on 11-24-2008 07:46 PM

[Pradeep_Bejugam]

Hi Denver,

Thankyou for the pointers provided. I have connected the DMM over GPIB and is being displayed under the MAX devices and interfaces. I am also able to communicate with the DMM using simple commands. Howevere when i use my CVI examples I am not able to get the correct measured value, but on the display the DMM shows the correct measured value. I am still not able to figure out the error. I have the latest drivers for Keithley DMM. I am calling the following sequence of functions

1. IviDmm_init

2. IviDmm_ConfigureMeasurement

3. IviDmm_Read

4. IviDmm_close

Even after calling auto zero (IviDmm_ConfigureAutoZeroMode) function before each measurement, the read function does not return the correct  measured value. I have IviDMM.h version 3.0 on my PC.

Let me know if I am doing anything wrong. Any kin dof pointers will be helpful to me.

Thanks & Regards,

Pradeep

[Pradeep_Bejugam]

Hi Denver,

I forgot to mention in my previous reply that we had switched to Fluke DMM and now we have created another setup for which we are using this DMM again. This is the reason for the delayed response to this thread.

I am having problem while configuring the DMM, IviDmm_ConfigureMeasurement. the parameters i am sending are

IVI_DMM_hnd_session

IVIDMM_VAL_DC_CURRENT

IVIDMM_VAL_AUTO_RANGE_ON

0.001

I am not able to read the correct value. The DMM displays overflow error.

However if i change IVIDMM_VAL_AUTO_RANGE_ON to IVIDMM_VAL_AUTO_RANGE_OFF  the software returns with the (Hex 0xBFFA0010) Invalid value for parameter or property error. If i ignore this error and continue reading the measurement I am receiving the value read on the DMM.

Can you please let me know if you have any information on this error.

Thanks & Regards,

Pradeep

[Dennis_Knutson]

Why did you post your LabWindows/Instrument control question to the LabVIEW board?