From 11:00 PM CDT Friday, Nov 8 - 2:30 PM CDT Saturday, Nov 9, ni.com will undergo system upgrades that may result in temporary service interruption.

We appreciate your patience as we improve our online experience.

LabVIEW

cancel
Showing results for 
Search instead for 
Did you mean: 

SMU (PXIe 4136) as a DC Current Source

Solved!
Go to solution

Hello everyone,

 

This is a project that I have inherited and I don't have much experience with SMUs.

I'm trying to use an SMU to get a DC Current. The current value can be changed and I would like to be able to turn the source ON and OFF.

The code that I'm using (attached here) is not mine. I get that it configure the Source and then it reads from it but this are the problems that I've encountered so far:

1. When I send the value I want to get (0.003mA and the Vlimit = 20V) just after opening the communication path, the SMU doesn't return the right value. It returns a small current value (1e-7) and it says that the compliance/limit is reached.

2. If, instead, I sent first 0A and 0V limit I receive the following error: 

        Invalid value for parameter or property.

        Device: SMU4136
        Property: Voltage Limit
        Requested Value: 0.0
        Maximum Value: 200.0
        Minimum Value: 6.0e-3

But after that error, when I send the usual 0.003mA and 20 V, I get the exact value!!

 

So my questions are:

 

how can I make the SMU to return the correct value right from the beginning and how can I turn the source ON (value different than 0) and OFF (0) without getting the previous error.

 

Thank you in advanced

 

0 Kudos
Message 1 of 6
(1,061 Views)

Can you post the VI for LabVIEW 2018?

 

How is your physical electrical circuit? You can't push a current without a load.

0 Kudos
Message 2 of 6
(1,052 Views)

I attach here the subVI in LV 18. I know that you cannot push a current without a load... What I'm wondering is why when I sent the current value that I want it doesn't work, sent 0 and get the error, and sent the current value again, this time works.

 

I think that is independent completely to my electrical circuit. Why the first time doesn't work and after the error it works?

 

0 Kudos
Message 3 of 6
(1,038 Views)

Sorry I misread your question.

 

Can you try to add the DCPower Commit.vi function just before DCPower initiate.vi. The error you get is correct, you cannot set a limit of 0V.

 

Btw, you don't have to manually set the precise current level range. If you set 5 mA, it will automatically round up to the nearest valid range (10 mA in this case). So you can remove those case structures.

 

 

0 Kudos
Message 4 of 6
(1,024 Views)

Hi,

Thank you so much for your input. I figure it out what it was... You were right about my circuit setup. I didn't realize that after the set up of the current some relays were closed to have some resistance. That's why the second time I always got the right current but never the first time.

One last question, how could I turn off the current source then? If when I sent 0A it gives me an error.

I will also remove the case structures

0 Kudos
Message 5 of 6
(970 Views)
Solution
Accepted by topic author michberk

Glad you figured it out!

 

To disable the current, use this function:

 

Basjong53_1-1693405912000.png

 

 

0 Kudos
Message 6 of 6
(964 Views)