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All about Keithley DMM7510. Bugs and features, recipes, advice, notes.

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essele:

--- Quote from: Kleinstein on June 11, 2020, 09:22:27 am ---The reduced resolution is really odd. There may be  reason to use reduced resolution for intermediate data to save on the memory - though still odd, as 1 µV resolution would be more than 24 bits and 32 bits would give enough resolution.

--- End quote ---

Yes, I had assumed this originally, but the internal data is absoutlely fine (that's what I used to do the excel graph) and you can zoom in and see the full resolution, so it's purely some unnecessary (in my view) rounding ... may be for performance, but I can't really see it.

There are so many horrible (but easy to fix) things with this meter .. just looking at the above screenshot ... why would you show min, max, and avg to 10uV resolution? .. it just makes them useless, I think I'd rather they weren't there at all!


--- Quote from: Kleinstein on June 11, 2020, 09:22:27 am ---There is another not so nice feature that was noted before: the grid lines are 1.1 µV apart, which is an odd choice. At least it looks like exactly 1.1 with no extra rounding error at the labels.

--- End quote ---

Don't get me started on the auto-scaling!  I keep meaning to capture screenshots of all the bizarre ways this manifests itself. I can understand the 1.1uV from a pure "best efforts" scaling perspective, but we should have the ability to set a min and max ... being only able to set to factors of 10 per division is awful (and again I don't understand this, their autoscaling can set it to whatever it wants) but we can only do 1uV, 10uV, 100uV etc. Ugh!

The graphing has the potential to be so much better than others (like the 34470 for example), but the implementation just lets it down all over the place. Still, I guess you can always export the data.

MegaVolt:
print(display.lightstate) always returns display.STATE_LCD_OFF after power-up

At the same time, the device screen is turned on.
This variable starts to work normally only after writing any value to it.

MegaVolt:
The device allows you to set NPLC with an accuracy of 1 ns, for example 10.001 μs. Does that make any sense?

Kleinstein:
It could make sense to set the integration time to a specific value with rather high resolution: if there is some extra low frequency signal floating around not related to mains, one could set the time to get good suppression of this frequency.  No real need for 1ns resolution, but it does not really hurt. It is more like odd how they implement this. I could understand 1 µs or 100 ns as the clock used.

MegaVolt:

--- Quote from: Kleinstein on June 16, 2020, 01:52:00 pm ---It is more like odd how they implement this. I could understand 1 µs or 100 ns as the clock used.
--- End quote ---
I also wonder what the real step is. We’ll have to put on experiments and try to understand how the device works :(

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