variable DC power supply virtual bench

[Edmond_Dantes]

Hi everyone,

I'm trying to programme the virtualbench DC power supply to have a variable value of DC current. 

I've tried with the example in figure "power_supply_v1.0" and it works, but I have to set all parameters from the front panel. Anyway, it is not possible to set by hand parameters to cover a time interval of 90 minutes by varying DC value after few seconds.

So I created a file containing voltage, current and time and for each row of the file I would to receive V*I power for the duration of the third column, as in:

"Voltage (V)"               "Current (A)"                      "Time (s)"
2.71635117696125   0.773114812272379        5
1.25706738077910   0.881681142450407        6
2.89286154926806   0.734092093476126        1
4.57738299516686   0.406432206360085        6
4.47798263072198   0.604178745602068        4
2.41253308690020   0.641105051660087        1
2.21369988881868   0.127466836015375        2
1.55877476124154   0.496191996945931        4
...                                      ...                                         ...

The vi I have written is that in figure "power_supply_v2.0". But it doesn't work and I was not able to understand the error message it reported.

Thank you,
Ed

[WilliamEarle]

Hi Edmond,

From your probes, it looks like you are wiring 0.00 into the current limit, which is causing the error. The minimum current setting is 1% of full-scale. Full-scale is 1A on the 6V rail, and 500mA on the other rails.

Regards,

William Earle

Software Engineer

NI R&D

[Edmond_Dantes]

Thank you for the answer, William!

The first current value I wire is that of the first row in the table I reported, that is about 770 mA. 

I think the problem is not the value 

[WilliamEarle]

Can you attach your VI?

Regards,

William Earle

Software Engineer

NI R&D

[Edmond_Dantes]

Hi William,

I attach my VI and the txt file I use to load values of voltage, current, and duration of the DC stimulus.

Regards,

Ed

[WilliamEarle]

Hi Ed,

For the +25V rail the valid current values are 0.005 to 0.500. So some values in that txt file, for example 0.00385915886072064, would cause the error you're seeing.

Regards,

William Earle

[Edmond_Dantes]

Hi,

I select the +6V channel before lauching the VI, and it doesn't start despite the correct values.

[WilliamEarle]

Hi Ed,

When I run your VI, I'm able to go through it without error if I force 0.01 as the min current (0.01 is the minimum value for the 6V rail).

I cleaned up your VI a little and attached it. The key thing is I'm using the Max & Min VI to force current to be >= to 0.01.

Do you still get any errors with this VI?

Regards,

William Earle

[Edmond_Dantes]

Thank you so much! 

I have just found the problem and I would have answered shortly.

I changed my .txt file by rounding values to 2 decimal points and, in this way, the vi works.

Thank you again!