Measurement uncertainty app for Keithly 6500 DMM

[Krampmeier]

I always found it annoying that DMMs like the Keithley 6500 and 7510 and their Keysight counterparts don't display their measurement uncertainty along with the measured vaule, as the Wavetek 1281 and the Transmille 8104 can do.
However, the Keithley meters offer a powerful scripting feature which lets us create our own enhancements.
Consequently, I created a small TSPA script application which allows to display the absolute and relative measurement uncertainty of the currently measured value along with the error limits.





For remote control, it offers the possibility to get the measurement uncertainty of the last value in the measurement buffer.


The script contains all the information from the specification sheet, including all the footnotes.
In addition to that, the operator can get hints for improving the measurement uncertainty, based on the current instrument settings.


The app is licensed under the CC BY 4.0 license and can be downloaded for free:

https://github.com/Krampmeier/uncertainty

However, as this is a hobby project, I cannot guarantee fitness for any purpose. There may still be errors or bugs. I'll be happy to accept pull requests with improvements. Feel free to create your own fork for other DMMs like the 7510, or even the Keithley SMUs.

[maat]

Wow, that is neat!

[NaxFM]

This is great, thanks!
I thought about writing a script exactly like this for my DMM7510 for a long time, but never had the will to learn the tsp language.
With a slight modification it works on a DMM7510, but i want to implement new features, like an info screen to inform of the status of autocal and internal temperature.
Right now i have it opened in Visual Studio to modify it. I'll work on it for a few days ( I first have to learn everything) and I'll post the modified version with all the changes compatible for the DMM7510.
I've just started playing with it, right now i'm tying to understand why sometimes it gives me absurdly high numbers for the relative uncertainty. I know i need to calibrate it, but i doubt it's this off...
Thank you for your work, it will be much easier for me to start from an already working app and modify what i need.

[Neoname]

This is very interesting! Did you have any luck making the DMM7510 version?

[Smokey]

This is neat indeed.  It's always frustrating trying to figure out if a measurement is in spec for a piece of equipment and what the rated uncertainty actually is for a given measurement.  While I don't have a DMM6500 (I wish), I might need to add something similar to my python control scripts for the stuff I do have.

[mendip_discovery]

If you are going down that route you could use, https://sandiapsl.github.io/ in Python to help you.

https://github.com/sandialabs/suncal

[calenguk]

If you have any measurement experience uncertainties are quite straight forward. Your biggest cause of "error" is the imported uncertainty. Always check to see if front or rear inputs were used as this can actually make a difference of 1uV or more. Temperature coefficient is another cause of error along with connection errors if you use cheap or poorly made test leads. Any reputable calibration company should ensure a 4:1 ratio on any measurements they make on your multimeter. Insist on an accredited 17025 calibration and ensure the company you use calibrates the multimeter across all the ranges you need. Some calibration companies follow manufacturer calibration points but these may not cover the values you are measuring. A classic is AC current calibrated at 1kHz when you use it at 40 to 60 Hz so without these values you can not be sure the multimeter is accurate or even meets the manufacturer specification. Just because they say it will doesn't allow for faulty circuitry.