Unwanted voltage spiking during measurement with NI 9239

[weazidaki]

Hello guys, I am in the process of learning Labview and I am running into this issue where the voltage that is measured using the NI 9239 shows some weird spiking right before the current supplied is increased. For context, the setup that I am doing is to measure the resistance of a thin film by using 4-wire method where a Keithley 2450 SMU is supplying the current and the NI 9239 is measuring the voltage. I used one of the Keithley 2450 examples, output list and acquire, and I inputted a list that went from 1mA to 5mA and back to 1mA. Additionally, I simply added the DAQ assistant to allow the NI 9293 to measure the voltage. Here is a picture of the front panel where it shows the weird spiking. 

I am wondering if there is a way to get rid of this issue.

I have also attached the relevant VI.

Thanks in advance.

[nuclear34]

Hello guys!

I am trying to automate the Keithley(voltage source) using LabVIEW. I want to send a step or pulsed voltage signal to an external resistor using Keithley 2450 and measure the current through the resistor using the NI-DAQ voltage input module. Here I attach my block diagram. 

I am sending a pulse through the CSV file, but I don't know how I can send 1V for 25Ms and 2V for another 25mS!

here I can send the pulse but cannot control the time!

[GerdW]

Hi nuclear,

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@nuclear34 wrote:

I don't know how I can send 1V for 25Ms and 2V for another 25mS!

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So you need 25 Megaseconds and 25 milliSiemens?

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@nuclear34 wrote:

here I can send the pulse but cannot control the time!

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What does the Keithley manual say about "controlling the time"?

Does your device offer (special) modes to define short voltage pulses?

Btw. this seems related to the question of your colleague, isn't it?