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
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
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)
How can I enable this setting? Am I missing something in here?
Thanks,
Hardik
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
Hello Axel,
Upon checking R-X mode again, I see that CV-IV Switch doesn’t switch to CV-HI and CV-LO mode. That means it is not measuring anything other than noise of the instrument. The data that earlier I shared was just a noise and wanted to ensure that connection is stable via LPTLIB server. I’m 100% sure because when I use the same CV-IV Switch module for SMU based measurements it is able to switch to SMU mode and perform accurate measurements. I also verified from Clarius and see no issues.
In the above screenshot, the highlighted red box doesn’t work properly when used LCR Meter K4200SCS driver. The green highlighted box represents SMU based measurements using 4200SCS driver. Below are the settings that I’m utilizing to connect the instrument.
In my case, all the terminals show only in SMU even when the CVU is under measurements.
Can you please help to see what exactly causing this issue?
Thank you,
Hardik
Hello Hardik,
thanks for performing the further tests!
Good to know that the post processing is not the problem.
The Keithley 4200 CVU LCRmeter driver was originally written for a parameter analyzer that is used without a CVIV Multi-Switch. I guess that there the device under test is directly connected to the CVU card and the SweepMe! driver works without any issues.
You can also cross-check this by using the CVU cards without the CVIV Mutli Switch between just to see whether correct data is obtained.
How to solve it? There are basically two approaches:
One could create a SweepMe! driver for the Keithley 4200A-CVIV MULTI-SWITCH that is designed to switch to a certain operation mode. The driver would be made for the Switch module which is then added to each branch and changing the configuration before a certain measurement is requested (IV or CV)
One could add the support for the Keithley 4200A-CVIV MULTI-SWITCH as part of the existing drivers for the SMU and LCRmeter module. Each driver is checking before a measurement whether the multi switch box is connected. If so, commands are sent to change to the requested measurement.
The second approach is more plug&play and needs less input from an user which is why I would prefer it. Still, one needs to check the manual of the instrument carefully, before makine a decision.
You can basically implement those changes on your own via the open driver interface, but it could also be helpful to make use of our professional services in order to implement the changes. Feel free to contact us via contact@sweep-me.net and we can support you with the creation of the driver(s).
Thanks and best,
Axel
