SMU

[min80]

Hi, 

Im using SMU 4132 to force voltage (20V) and measure current (< 10uA). 

I can get stable current measurement through soft front panel but when at labview coding, my first measurement always will measure 10uA then subsequent reading only will go to the desired measure current I want. 

Why the first measurement always will go to 10uA? 

Thanks. 

[KateB]

1. What is NI-DCPOWER version you use? You can check it from Start>>All Programs>>National Instruments>>Measurement & Automatio>>My System>>Software. This is need for feedback this problem to R&D.

2. If you've not used NI-DCPOWER 1.4, you should try upgrade it from https://www.ni.com/en/support/downloads/drivers/download.ni-dcpower.html#324382

3. Please post your code so that I can give you a work around on this problem.

[min80]

Hi, 

Thanks for the reply. Yes. Im using version 1.4. Checked! 

Below is my code. Please help. Thanks. 

[KateB]

1. You can use array subset, and put 1 to index. This will remove the first element.

2. This information will feedback to R&D for further information.

[min80]

HI, 

Im using Single point source mode, thurs only single point will be measure. 

Only index 0 in the array have the reading. 

[kirsch]

Hello

From the code you posted, it cannot be determined how you are configuring the device. What is the output function? What is the source mode? etc.

Also, remember that depending on your load, the voltage will take a different amount of time to ramp up. You are measuring immediately after initiating. I think that you want to configure the time for Source Complete Event to be emitted and wait for Source Complete Event before you measure, as to give your source enough time to settle.

Marcos

[Steve_B]

As Marcos described you can configure the hardware to wait for a specified amount of time before making a measurement. A good way to configure that using the 4132 is to set the source delay and to configure the hardware to measure automatically after the source complete signal is sent. We have several shipped LabVIEW examples for programming the 4132 using the NI DC-Power driver that can be a good starting point for developing an application. You can navigate to the Example Finder from LabVIEW (Help>>Find Examples...). The example I would point you to is NI-DCPower Hardware-Timed Single Point.vi and you can navigate to it by the following path Hardware Input and Output>>Modular Instruments>>NI-DCPOWER (DC Power Supplies). This example will configure a source delay as described above, set an output voltage and make a measurement, then set another output voltage and make another measurement. 

When you first set an output voltage it can take some amount of time to reach the desired output state. This amount of time will depend on the connections, cabling, and the DUT. For example a capacitor on the output of the 4132 would require time and current to charge its voltage up to the desired set point. This will follow a typical charge/discharge curve for a capacitor. Once the charging is complete the voltage will be at the set point and the current will drop back down to 0A. It is likely that you have some capacitance in your system that must be charged to reach your voltage setting and once that charging has completed you are reading the expected value. Setting a source delay and measuring once it is complete will allow for the charging to occur, but the measurement(s) will begin after it has completed. The amount of necessary source delay will depend on your system.