Keithley 2410, current readings

[_natalie_]

Hi everyone,

I am using a Keithley 2410 1100V Source Meter.  I am using it to source a voltage.  My LabVIEW proogram (made with LabVIEW 2015) controls the Keithley Source Meter, a function generator and an oscilloscope.

In my program, the source meter outputs a voltage, the function generator pulses the gate of my transistor X times and the oscilloscope is triggering on the gate voltage and recording the drain current and voltage.  Once the 'scope has triggered X times, the data from the 'scope is output to a csv file.  All of this is working well.

I do not need the source meter to output to a csv file, and I know from my 'scope measurements it is outputting the correct voltage.  However, I would like the current being measured by the source meter to be displayed on the front panel, but it is not.  If I run the measurements manually, it does, but not when it being done remotely.

I attached my VI which sets up all of the commands for the source meter.  I did not use any of the drivers for this meter.

Thanks in advance!

[Minions]

Your Keithley SMU 2410 has setting for that.  Check the manual under DISPLAY.  They have a note in there that, "The display may be disabled for faster operation."  Also, it may be set that the display is not updated while the STORE (Store measurements in buffer) option is selected.  You may need to change the STORE option through the front panel while the other can be changed through SCPI commands.

[_natalie_]

Thank you for your help!

Unfortunately, I have realized I have other measurement problems.

What I want to do with the source meter component of my program is to have it simply supply a voltage.  I am having issues with it outputting the voltage.  I will be supplying up to 600 V.  I realize that with this piece of equipment the maximum current compliance is 20 mA, and I need to adjust the current measuring range, which I have.  When I use my program to apply X volts, the compliance units start blinking and on "the line" above that, there are just dashes instead of any measured current values.  The measured current I am expecting is about 0.5 mA.

I retract what I said in my first post.  I do not get the expected current on the 'scope, so therefore, the source meter is not supplying the voltage.

If I run this manually, I do not get this problem at all. It must be a setting in my program, but I just do not see it.  I have reattached my VI so that you can see my updates to the code.  I feel like I am on the right track.  Is there an order I am getting wrong?  

[Minions]

Here I am guessing at this from the information that you have provided without a schematic, but it sounds like you are connecting the SMU output (600V) to the collector of a transistor and pulsing the base.  If the emitter is connected to the other SMU output (V-) and ground, you are creating a short to ground through the transistor (less Vdiode drop).  You will get WAY more than your 0.5mA until the transistor blows; then 0A.

[_natalie_]

Sorry, I didn't think to connect a schematic.  I actually don't have one handy, unfortunately.

The source meter is applying a bias across the drain (collector) and source (emitor) of a HEMT transistor.  I have a function generator applying a pulse across the gate (base) and source of the transistor to turn the device on and off.

[Minions]

Exactly, you are creating a PWM output in which when the gate is off, Vce is 600V with 0A and when the gate is on, Vce is 0.7V with current maxed at the set or instrument current limit.