SMU 4139 terminals to connect to 2535 switch matrix modules rows, and use labview to switch on some columns to their rows and measure a resistor value using pulse current function in SMU

[KimWang1234]

In our application, we had SMU PXIe-4139 and some PXI-2535 switch cards on the same chassis. We physically connected the SMU HI, Sense HI, LO, Sense LO terminals to the PXI-2535 switch card rows. Then we used Labview program to switch some columns to its rows on the same card to measure a resistor value, which is connected between Sense HI and Sense LO.

We can not measure the resistor value as the current is 0. 

 I attached the labview code in the posting. The main VI is: SMU Measurements with Multiple Switch Modules.vi

Has anyone used this kind of setup to measure something via a SMU module?

Thanks,

Kimberly

[red.free]

Have you seen this article? Use the example to verify the SMU is able to read the value correctly.  If it’s not, isolate the SMU from the switch.  Verify that your VIs are measuring the resistance in a similar way.

http://www.ni.com/example/30347/en/

Have you tried running the test using test panels to make sure the hardware is connected properly?

[KimWang1234]

I tested to manually turn the switch columns on to connect to the rows, use MAX SMU test panel to see the measurements, I got the same results.

What we found out that if we connect the SMU LO to the PXI chassis ground, we could measure the resistor value, but little lower than the  real value (real resistor is 4 ohm, we measured 3.6 ohm). It seems like the switch modules row to the SMU LO has to be grounded somewhere?

Thanks,

Kimberly

[red.free]

Is it always .4 Ohms off regardless of the resistor size?

Have you tried other sizes?

[KimWang1234]

We tried to put different resistor size around 2 ohm, it behaved the same.

Now we found out that we can use the SMU test panel to measure the resistor value if we force pulse current level smaller than its range, for example we gave 100 ma range, but the current level was 10 ma or 20 ma, it worked. But when I ran my labview code using scanlist method, it did not work.

Does anybody know what are the default settings for the SMU that their test panel used on pulse on time, pulse off time, ...?

[red.free]

Did you get the same results from the example file included with the tutorial?

The pulse width values for the 4139 can be seen in the specifications guide.

http://www.ni.com/pdf/manuals/376115d.pdf

[KimWang1234]

The solution was based on simple switch example and SMU pulse current example in LabVIEW.

The problems were that we did not ground the LO to PXI chassis ground, therefore, the leakage current caused the the SMU to Over Voltage Protection mode, after that mode even the LabVIEW program executed to closed some switches, they remained open until we restarted the PC and switch systems.

After reading the following articles and with NI supports, we solved the problems by putting 1 Mohm resistor between SMU Sense LO and LO and 100 ohm resistor between LO and the PXI Chassis ground. We used LabVIEW examples on niswitch and nidcpower pulse current vis to solve the problems.

http://digital.ni.com/public.nsf/allkb/FD603AF66DCC934386257403006C4109?OpenDocument

Attached are the LabVIEW codes. 

[red.free]

So, is this issue resolved or are there any outstanding questions?

If it is resolved, mark the solution for any future inquiries.

[KimWang1234]

This problem is solved. Still question is how to setup the SMU pulse on and off time to optimize its operation. 

[red.free]

I always recommend starting with an example that has the general functionality you need and modifying it accordingly to fit your application. 

I would also recommend browsing through some of the documentation NI has for SMU configuration.  The link below might be useful or point you in a helpful direction.

http://www.ni.com/white-paper/51929/en/

Also, if this is a new question, it might be helpful to create a new forum post for the new question.  Keeping to one question per thread usually helps get better insight.