Keithley 4200SCS CV/IV Switch support

General
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Hello sweep-me team,

I’m looking for a sweep me module which can support measurements using Keithley’s 4200A CV/IV switch instrument link - Model 4200A-CVIV Multi-Switch User’s Manual | Tektronix. We use SMUs to connect to the switch for performing CV/IV measurements. However, on checking the sweep me SMU drivers for Keithley4200SCS it doesn’t supports any CV based measurements. Can you please support on how can i setup these or if it requires driver development from Sweep me?

Thanks,

Hardik

1 Like
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Hi Hardik,

thanks for asking!

There is a dedicated driver for the LCRmeter module to address the CMU card of the Keithley 4200A parameter analyzer:

https://sweep-me.net/device/277/Keithley_4200-SCS

We recommned using our lptlib server, a program that translates commands sent via Ethernet/TCPIP into program calls of the lptlib.dll; it can be downloaded via your SweepMe! account. You can find more infos on the above mentioned the driver page.

Feel free to test it and let us know if you have any questions.

Thanks and best
Axel

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Thank you Axel for the quick response. I have setup LPTLIB server on the Keithley-4200SCS A already and it is communicating to the master PC very well. I tested R-X mode already and see no issues for measurements.

The only problem I currently see is that the drop-down box for Operating mode is greyed out i.e. not letting me choose Cp-Gp mode. It is stuck at R-X mode. Please see my screenshot that i have attached below for the CV/IV unit. (I also tried selecting post-processing where Cp-Gp are enabled however, this not providing ideal measurements)

image
image1887×1037 154 KB

How can I enable this setting? Am I missing something in here?

Thanks,

Hardik

1 Like
4

Hi Hardik,

great you were able to get it running.

Instead of each driver implementing the calculation of Cp, Gp, Rp, and so on, we have designed the LCRmeter drivers such that the as default respond with R and X being the real and imaginary part of the impedance. From these two values and the frequency, all other parmeters can be calculated assuming either a parallel RC or series RC circuit.

You can find the exact equations we use for post-processing in the Wiki article of the LCRmeter module:
https://wiki.sweep-me.net/wiki/LCRmeter#Post-processing

The advantage of our approach is that you can return as many post-processed parameters as you like. You are not limited to just Gp-Cp, or R-X and so on. It also helps to understand that most of these parameters are no real measurements but rather an interpretation in terms of a parallel or series RC circuit. Basically, one could also assume completely other circuits to derive a certain capacitance or resistance.

If an instrument returns Gp-Cp, it also applies already an interpretation of the measured data in terms of assuming an equivalent circuit.

If the Gp or Cp values are wrong, then either R or X are not correctly returned by the instrument or our calculation of the post-processing is wrong.
Could you provide further information why the values are not ideal and we will have a look where the problem occurs.

Thanks and best
Axel