Problem with CVi6 and HPE3631A Power Supply

[Gregoire Diehl]

Hello Group,

since i have upgrade to Labwindows/CVI 6.0, i get strange result from
my HP Power Supply, using the GPIB interface.

For example:
If i have a device connected to the Power Supply i can see the
following result on the instruments display.

1. Channel Output 5V 0.300 mA current
2. Channel Output 12V 0.124 mA current

If i want to read this result over the gpib interface (using the
hpe363xa_Measure function) i get difference results:

1. Channel Output 5V 3.000 mA current
2. Channel Output 12V 1.24 mA current

or

1. Channel Output 0.5V 30.00 mA current
2. Channel Output 0.012V 12.4 mA current

or

1. Channel Output 5V 3.000 mA current
2. Channel Output 1.2V 0.124 mA current

If i do the measureme
nt twice in follow i get the correct result with
the second function call.

Example:

1.Call of hpe363xa_Measure give this results:

1. Channel Output 0.5V 30.00 mA current
2. Channel Output 0.012V 12.4 mA current

and the 2. Call give this (correct) results:

1. Channel Output 5.0V 0.300 mA current
2. Channel Output 12.0V 0.124 mA current

I have downloaded the latest driver for the HP Power Suply from the
Nation Instruments Website (old is dated 05/17/99 and the newest dated
06/14/2000), but without improvement. Both driver Version give the
faulty results with CVI 6. With CVI 5.5 i have no problems reading the
correct values over the GPIB-interface.
Remark: A second call of the same function would return the correct
values, but the first call does not.

Can someone please point an assertion for the described behavior?
I would be very grateful for each assistance

kind regards
Gregoire Diehl

[pavanb]

Hello Gregoire:

Do you have two separate systems - one with CVI 5.5 and one with CVI 6.0. Which version of IVI engine do you have? What is the value used for resistance? In each case, the ratio of V and I is different which confuses me completely. This could be also a timing issue meaning that the signal doesn't have time to settle. What functions do you call before the Measure function. If you can send the code or at least an NI-spy output so we can see which functions are being sent to the instrument.

Right now you try to get voltage and get current, and then again to get voltage and get current and so on. What happens if you try to get current multiple times without getting voltage in between?

[Gregoire Diehl]

Hello Pavan,

> Do you have two separate systems - one with CVI 5.5 and one with CVI
> 6.0.
Yes, the system with CVI5.5 is running correctly. The other system is
running with both version: CVI5.5 & CVI6 and both gives the faulty
results.

> Which version of IVI engine do you have?
I?m using actually version 1.83. Before i have used IVI 1.60

>What happens if you try to get current multiple times without getting
voltage in between?
With the second call of the function i get the correct values.
For Example:

hpe363xa_Measure (hpe3631a, "1", HPE363XA_VAL_MEASURE_VOLTAGE, &volt);
.... returns faulty values

hpe363xa_Measure (hpe3631a, "1", HPE363XA_VAL_MEASURE_VOLTAGE, &volt);
.... same call return then correct values.

>This could be also a timing issue
Right, i?m examine in this direction at the moment. What me confuses
is that the errors occurs also in interactive mode (when i run the
function panel one by one manualy).

>What functions do you call before the Measure function.
1. hpe363xa_init ("GPIB::5", VI_OFF, VI_OFF, &hpe3631a);
2. hpe363xa_ConfigureVoltageLevel (hpe3631a, "1", 5.0);
3. hpe363xa_ConfigureCurrentLimit (hpe3631a, "1",
HPE363XA_VAL_CURRENT_REGULATE, max_5V);
4. hpe363xa_ConfigureVoltageLevel (hpe3631a, "2", 12.0);
5. hpe363xa_ConfigureCurrentLimit (hpe3631a, "2",
HPE363XA_VAL_CURRENT_REGULATE, max_12V);
6. hpe363xa_ConfigureOutputEnabled (hpe3631a, "1", VI_TRUE)
7. hpe363xa_ConfigureOutputEnabled (hpe3631a, "2", VI_TRUE)

then i began to read the data from the Power Supply
.... hpe363xa_Measure (hpe3631a, "1", HPE363XA_VAL_MEASURE_VOLTAGE,
&volt);
.... hpe363xa_Measure (hpe3631a, "2", HPE363XA_VAL_MEASURE_VOLTAGE,
&volt);

>If you can send the code or at least an NI-spy output
I have attached a small spy-file. Pleas look at line 3 & 6 and at line
9 & 12. The function returned different values. The exponent is wrong

I have open another thread in public.gpib.general, cause i think it
will fit there better. Please have a look at the discussion.

thanks & best regards
Gregoire







[Attachment Capture.spy, see below]