Andrea C

I disagree about the part availability.
As a repair part, item TF-245 is available component.  Contact your local Tektronix sales office.
It is a resistor network in SOIC-16.
 

In contrast to our SourceMeter products which can directly be current source or voltage source, a power supply is always a voltage source.

But even for voltage source, there is also the parameter setting for the current compliance limit.
A power supply can achieve current source (CC mode) behavior by deliberately operating it in current limit.

Suppose you have a device that is approximately 10Ω and you want to source 100mA through it.
So you’d expect a 1V potential to develop.
Configure the power supply for the 100mA limit and ask it to source more than 1V…..let’s say 10V.
It will not be able to achieve the 10V because it will first encounter the 100mA limit.
The power supply read back functions will show the appx 1V of potential and the 100mA of current.


 

Can you post a bit more information about your coding approach?
I am not fully understanding the situation.

Not sure this applies, but keep in mind that 2450 will process commands more quickly than 2400.
So a loop running on PC certainly can blast through more quickly.

It seems Windows has not properly associated the DAQ as a USBTMC device.
Until that is resolved, all the NI VISA based communications will not succeed.

In Device Manager, can you have it update the driver for the entry?
Or delete that entry and scan for changes.
You need Windows to associate the detected USB device as USB Test and Measurement device.

Sometimes, if a driver is not present when the plug-n-play device is first connected to Windows, Windows will make generic other device association.  With driver installed, need Windows to take a fresh look and make proper associations.

Your description of connections seems correct.

A multimeter does not typically allow adjustable source current for the ohms measure function.

To achieve what you describe, you need a current source and then use the dmm to measure voltage to have insight about the R.
A SourceMeter such as 2450 can be the current source.  It might also serve as the voltage measure, but check the specs against what you need.

The 2002 is 8.5 digit instrument whereas the 2450 is 6.5 digit.

Simply reboot the instrument will apply the factory default settings.
Also sending *RST command will restore default settings.

If no errors reported during power on, there are additional self-tests you can run from the menus.  Check the reference manual.

As for the negative number:  how big and what measure range is in use?  By how much does it exceed allowed error for the range?  Is best to have no test leads when checking the current measure offset error (open ckt).

If the error is just a little past expected values for the specifications, calibration might fix it up for you.
But if the error is very large, it may indicate a malfunction of some sort and require service.

With only two SMU channels, you will have to move cables for each step of the VDP measurement.
But for each step, one SMU forces current and other SMU forces 0A and measures V.

Is easier if you have 4 SMU channels, one for each contact point in the VDP test structure.
As needed for each step, each SMU can be current source, LO return or voltage measure, so no need to move cables.

KickStart will require a gpib connection to 2401.
The PC gpib interface should be from Keithley or National Instruments.
Use the utility software from the gpib interface provider to verify communication with 2401.
If works, then KickStart will be able to use it.

The +ILK is shorted to -ILK with a physical wire.
If using one of our 37xx-ST screw terminal accessories, we make this connection for you.
But if custom wiring to the DBxx mass termination connectors, keep in mind you need to either wire them to a interlock switch or jumper them if you want to close backplane relays on the 37xx card.

For just closing channels, either send a list of channels to be closed, or create a pattern and close/open by pattern name.

-- some TSP commands for channel closure

​​​​​​​reset()

channel.close("1001,1911")

print("******************")
print(channel.getclose("allslots"))
print("******************")


channel.open("allslots")

channel.pattern.setimage("1001,1911","patternA")

channel.close("patternA")
print("******************")
print(channel.getclose("allslots"))
print("******************")

channel.pattern.delete("patternA")