Author Topic: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.  (Read 6044 times)

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Offline MegaVolt

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Analog

Relay

* Secondary measurement without relay clicks - https://www.eevblog.com/forum/testgear/all-about-keithley-dmm7510-bugs-and-features-recipes-advice-notes/msg2180195/#msg2180195
* Additional information about the relay           - https://www.eevblog.com/forum/testgear/new-keithley-dmm6500/msg2022019/#msg2022019

DCV

* An input of 10 MΩ in the range of 0.1 V and 1 V creates an offset voltage of 5-6 μV and additional noise. Do not use this input impedance for accurate measurement. No solution. - https://forum.tek.com/viewtopic.php?f=363&t=141241

DCI

* Measuring current from sources with low internal resistance gives a big error. - https://forum.tek.com/viewtopic.php?f=363&t=141262

Digi V

* The input frequency band does not depend on the sampling frequency :( and depends only on the range. - https://www.eevblog.com/forum/testgear/all-about-keithley-dmm7510-bugs-and-features-recipes-advice-notes/msg2710538/#msg2710538
* At high digitizing speeds (> 200kSps), noise in the 0.1V range is very different from white noise. No solution. - https://www.eevblog.com/forum/testgear/all-about-keithley-dmm7510-bugs-and-features-recipes-advice-notes/msg2609100/#msg2609100

Temperature

* Does not support measurements for Pt1000. No solution.
* When measured from a thermocouple, it does not measure the temperature of the cold junction. Solution - https://www.eevblog.com/forum/testgear/all-about-keithley-dmm7510-bugs-and-features-recipes-advice-notes/msg2233422/#msg2233422

Digital

Digi V; Digi A

* Parameter dmm.APERTURE_AUTO does not work as described in the documentation. https://www.eevblog.com/forum/testgear/all-about-keithley-dmm7510-bugs-and-features-recipes-advice-notes/msg2648655/#msg2648655
* The position of each sample on the timeline has a virtual error due to the transfer of the internal timeline to the external. https://www.eevblog.com/forum/testgear/new-keithley-dmm6500/msg2140273/#msg2140273

Programming

* Low data reading speed via remote interface (v1.7.0). I could not get more than 800 KB/s (<7% 100MB Ethernet). This is about 50 KS/s (8 bytes of data and 8 bytes of time for 1 count). The processor inside the device allows you to work at higher speeds. No solution.
* The warm-up status on the remote interface can only be known once. The program launched the second time will not be able to get this status. No solution. - https://forum.tek.com/viewtopic.php?f=363&t=138795
* NTFS flash drive is not supported, only FAT32 works. No solution. - https://forum.tek.com/viewtopic.php?f=363&t=140287

Firmware bug`s fix history

1.7.0

Improved remote control of the device:
1. Data reading speed increased 3 times to 60 KSamples per second. (When reading a large buffer, the reading speed at the beginning is greater than the reading speed at the end. My error.)
2. Reading data digitized at high speeds (1 MHz) is performed without a preliminary long delay.
3. Virtal front panel works much better. If you return to the device using the http://IP_Device/front_panel.html link, you can open a window without a menu. It looks great on a smartphone :)))

Other:
4. The measurement block (trigger.BLOCK_MEASURE_DIGITIZE) now has the same name for the Measure and Digitize modes. (Just as it is done in the DMM6500).
5. The labels on the vertical axis on the graphs have become much better readable.

New bugs:
DigiV writes a large buffer with a pause in the middle. - https://forum.tek.com/viewtopic.php?f=363&t=142031

1.6.7

Link`s

https://www.eevblog.com/forum/blog/eevblog-731-keithley-dmm7510-7-5-digit-multimeter-teardown/
https://www.eevblog.com/forum/testgear/keithley-dmm7510-7-5-digit-multimeter-review-teardown-experiments/
https://www.eevblog.com/forum/testgear/7-5-digit-bench-dmms-comparison/
https://www.eevblog.com/forum/testgear/keithley-dmm7510-smu-2450-2460-problems/
https://imgur.com/gallery/Wbx7q
« Last Edit: March 24, 2020, 11:52:42 am by MegaVolt »
 
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Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #1 on: February 04, 2019, 07:07:30 pm »
Brad O I will be very grateful for the answers about 7510.

1. DataSheet promises 140,000 measurements per second via LAN (measurement + time). So far I was able to get a maximum of 15,000. What can I configure to get the reading speed stated in the datasheet? Binary mode is on.

2. How can you remotely know if the warm_up period has passed or not? Is there any flag or status for this?

3. I managed to get the error of measuring time beyond 20ns during the first 2s :(  It seems to me that these outliers occur at random times and are not related to the first 2s. I also saw peak to peak emissions on the order of 900ns on a sample of 8MS.

4. How can I reset the device without turning off the power? I notice that if the device stopped working as needed (does not respond via the network or something strange responds), then you can fix it only by turning off the power. It is very uncomfortable. We must wait again for an hour and a half. Resetting from the touchscreen does not help: (

 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #2 on: February 04, 2019, 08:10:03 pm »
I see a clear periodicity. Every 5s is a new failed time.

Does this mean that data is selected at the wrong moment in time? Or is it a timeline problem and you can ignore them?
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #3 on: February 05, 2019, 09:38:16 pm »
Current and voltage measurement without relay clicks. This is possible if you select secondary measures in accordance with the tables below:

 
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Offline MegaVolt

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When measured from a thermocouple, it does not measure the temperature of the cold junction. See the first picture.

A possible solution to this problem is indicated in the second picture.

 

Offline MegaVolt

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New bug`s: The problem of changing the size of the buffer.

UPD: To repeat the bug for the newly turned-on device, you need to repeat the script twice. But between operations you need to disconnect from the device and reconnect. The red arrow indicates the location of the reconnection.

UPD2: The maximum size that can be obtained after the appearance of the bug is only 7997000.


« Last Edit: May 01, 2019, 10:25:18 pm by MegaVolt »
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #6 on: August 11, 2019, 08:00:29 pm »
New bugs DMM7510 (features):
And there is nothing to complain about. Branded short Keythley 6820.

 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #7 on: August 11, 2019, 08:07:33 pm »
If you have access to the Keythley DMM7510 please check to see if you have the same bugs.
I'll be very grateful.
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #8 on: August 28, 2019, 02:02:53 pm »
The device is mocking me. I can’t understand how it works.

I was trying to figure out how to control the aperture for DigiV. To do this, I applied a rectangular signal with a frequency of 400 kHz from the generator (high level [2.5V] 90% of the time; low level [-2.5V] 10%).

And he turned on the digitization with the same frequency of 400 kHz. (frequencies are not synchronized). The period is 2.5 μs. This means that the aperture can be 1 or 2 μs. And Auto should correspond to 2 μs.

And I was hoping to see two types of graphs.

BUT!!!! I see 3 types of graphs. The graph when installing Auto Aperture is not similar to the 2 μs graph .... It is rather similar to the graph when the samples go through 1.25 μs. But this is only an assumption. In fact, I do not know how it is done in the device.

Though disassemble this miracle box and become an oscilloscope on the DAC :(

 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #9 on: September 27, 2019, 12:05:38 am »
Measured the cutoff frequency in DigiV mode.
The cutoff frequency does not depend on the sampling frequency :(.

For ranges: 0.1 V; 1 V; 10 V cut-off frequency: 600 MHz
See the picture.

For the 100V range, the cutoff frequency is 7.5 kHz.

For 1000V, the cutoff frequency is 17.5 kHz.
 
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Offline Kleinstein

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #10 on: September 27, 2019, 07:54:02 am »
The quite limited frequency response in the 100 V and 1000 V ranges is a bit disappointing. Especially the low cut of for 100 V is odd, as there is the same divider and just the amplifier in x 10 mode instead of x 1. This corresponds to the 1 V and 10 V ranges, that seem to be fine to much higher frequency.

For 1 MSPS sampling the Nyquist limit is at 500 kHz - so there should be large drop in this range. If looking at more than just the pure RMS or peak to peak values, there should be signs of aliasing. So how does the waveform look for something like a 550 kHz signal, when measured at 1 MSPS.

It looks like there is no anti aliasing filter, not even a fixed one (e.g. 400 kHz) for 1 MSPS sampling.
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #11 on: September 27, 2019, 08:54:40 am »
The quite limited frequency response in the 100 V and 1000 V ranges is a bit disappointing. Especially the low cut of for 100 V is odd, as there is the same divider and just the amplifier in x 10 mode instead of x 1. This corresponds to the 1 V and 10 V ranges, that seem to be fine to much higher frequency.
If you look at the noise in the specification, then the 100V range has a higher noise level. Is the band reduced to reduce noise?
Quote
For 1 MSPS sampling the Nyquist limit is at 500 kHz - so there should be large drop in this range. If looking at more than just the pure RMS or peak to peak values, there should be signs of aliasing. So how does the waveform look for something like a 550 kHz signal, when measured at 1 MSPS.
Yes, all crossings across the Nyquist border have a drop. This is clearly visible if you change the frequency linearly and not in steps.

And all that is higher than the Nyquist frequency is spectrum overlay. The ADC has a very good sample/hold device with sampling times of the order of 100 ns.
Quote
It looks like there is no anti aliasing filter, not even a fixed one (e.g. 400 kHz) for 1 MSPS sampling.
Unfortunately it is so. As Bred said, the user must make an external good filter himself if he wants to watch the signal in a limited band. If this is not done, then all the noise from the Nyquist frequency to the MHz pair will fall into the signal :(((
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #12 on: November 22, 2019, 01:07:50 pm »
Updated the header:
Added by:
- improvements to the new firmware;
- added new bugs and features;
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #13 on: November 22, 2019, 01:18:28 pm »
The new screen of death.
The device after it did not react to anything. I had to reboot. Unfortunately, I can’t say how to repeat it. I switched between DCV and Digi V modes, used a large buffer and played with the Count parameter.
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #14 on: November 25, 2019, 10:09:07 pm »
Yes the 100V and 1kV ranges have bandwidth limited by the huge 10Meg divider. Internal changes when going from 100V and 1kV can make those differ a bit as well. The divider wasn't AC balanced because most of the user base doesn't do high voltage at high frequency generally.

The 100V range behaves very strangely.
For example, I see a reaction from a change in input resistance.
At 10 MΩ - 750 μV
At Auto - 65 uV

At the same time (Auto) it can be seen that emissions appear on the noise track :(

Is there any difference between 10 MΩ and Auto?
If you select a range of 1000V there is no such effect.

 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #15 on: November 26, 2019, 08:35:47 am »
There is an internal signal path difference based on selection 10M or Auto.
Can you reveal the details? What is the difference? What is the input impedance in Auto mode? Does the device have the ability to work with an input impedance of 1 GΩ for the ranges 100V and 1000V ???
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #16 on: November 29, 2019, 10:14:08 am »
New firmware 1.7.0. Trying to write a large contiguous buffer (8 000 000 samples) at a time:
Settings:
Digi V + [Freq=1MHz] + [Aperture=1mks] + [count = 8,000,000]

[attachimg=1]

When time-critical processes are not implemented on the hardware, but are given to programmers, it’s a disaster :(  When the product is more than 5 years old. But he still cannot do a simple operation - write a buffer of a given size with a given frequency. But on the screen you can run the watch and other toys.  :palm:
 

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #18 on: March 24, 2020, 11:51:59 am »
Updated the header:
Added by:
- firmware 1.7.0 аdditional Information;
- link`s;
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #19 on: April 04, 2020, 03:21:21 pm »
Measured the cutoff frequency in DigiV mode.
...
For the 100V range, the cutoff frequency is 7.5 kHz.
For 1000V, the cutoff frequency is 17.5 kHz.
I figured out different cutoff frequencies for 100V and 1000V

17.5 kHz available for:
1000 V + 10 MΩ
1000 V + Auto
100 V + 10 MΩ

7.5 kHz becomes at a combination of parameters 100 V + Auto

Why, when choosing the input resistance Auto for the range of 100 V, the strip changes I do not know. This is some kind of mystery.

I tried to measure the input impedance for Auto and for 10 MΩ = 10 MΩ without changes.

Something inside limits the band.
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #20 on: April 09, 2020, 01:36:24 pm »
Generally, the AUTO setting changes the input path with different amplifiers which is why you will always see noise differences and bandwidth differences.
Where can I read more about this? I want to understand what exactly is happening. And why it works on the 100 V range but doesn't work on the 1000 V range
Quote
I can say this behavior is planed to change on next hardware revision.
Unfortunately my guarantee has already ended :(

Quote
Would you consider posting your findings on the Tek forum or engage an applications engineer (Im not one - sorry) ?
You might find you can get quicker / better answers by doing so. Just a thought to try and help you out.
I posted this on the tek forum. But in my opinion he is long dead. I would love to talk with someone else, but unfortunately I can’t find the contacts of specialists who understand how the device works. I only come across Keithley's security experts. : ((

Can you tell me where to find them?
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #21 on: April 13, 2020, 11:58:19 am »
Let's try to figure out how the frequency and the aperture parameter for the Digitize mode are set.

1. Sample Rate:

It seems we can set any frequency from 1 kHz to 1 MHz. But this is not so. This is easy to see if you try to set the frequency of 999999 Hz. The device will rearrange the frequency 979592. That is, frequency step of the order of 20 kHz. And the next one will be 960,000 Hz.

To understand why we will look into the device and find a 48 MHz generator next to the ADC. (why at 50 MHz is a mystery to me.) Accordingly, the period must be a multiple of the period of the generator.

For 1 MHz - 48 periods.
The next frequency can have 49 periods. This is 979 591.83673 ... Hz or rounded 979592 Hz (which the device shows.)

In order to find out how many periods the formula will be set: T = Rounded up (Fgen / Fx).

Real sampling rate = Fgen / T;

2. Aperture

This parameter did not give in to cracking long enough. In manual mode, when we set the aperture manually by setting the number of microseconds, everything turns out fine. t = 1 μs and the apertura parameter sets the number of averaged samples N. (The device allows you to set up a fractional aperture; maybe it works; maybe not. I haven’t figured it out yet).

But there is one caveat. For example, for a frequency of 333334 Hz, as shown above, the period will be exactly 3 μs and it would seem that we can choose a manual aperture 3. But the device says that the maximum aperture is 1/333334 = 2.9999 ... which is <3 μs and does not allow us to set value of 3 mks. only 1 and 2.

Now let's move on to the Auto parameter.
It works like that. Calculated N = rounding down (T / 48) we get the number of averaged samples.
And then we calculate t = rounding down (T / N)
As a result, for a frequency of 333334 we get T = 144; N = 3; and t = 48
And for a frequency of 384000 we get T = 125; N = 2; and t = 62 i.e. readings will be taken after 62 then after 63 periods and so on.
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #22 on: April 13, 2020, 12:11:49 pm »
A table with all values of frequencies and parameters T, N, t for Auto mode.
 

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Offline Electro Fan

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #24 on: April 21, 2020, 04:27:41 pm »
Can someone describe roughly (overall) how the issues discussed in this thread relate to the 6500?  For example, when 7510 issues surface are they likely to be similarly present in the 6500 and then fixed in the 6500 after being fixed in the 7510?  Or does it work in the reverse sequence?  Or some of both sequences?  Or are the issues lists for the two models dissimilar enough that the features requests and bug lists have relatively little relationship to one another in terms of being found and addressed?  Or something else...?
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #25 on: April 21, 2020, 09:03:55 pm »
Can someone describe roughly (overall) how the issues discussed in this thread relate to the 6500?  For example, when 7510 issues surface are they likely to be similarly present in the 6500 and then fixed in the 6500 after being fixed in the 7510?  Or does it work in the reverse sequence?  Or some of both sequences?  Or are the issues lists for the two models dissimilar enough that the features requests and bug lists have relatively little relationship to one another in terms of being found and addressed?  Or something else...?
I think the only way is to learn to repeat the described steps and check if there is a problem in 6500.

I tried to post problems in the topic about 6500 but I was asked to start the topic separately because the DMM7510 "is very different from 6500."

I will be grateful if someone checks the problems found at 6500.
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #26 on: April 28, 2020, 12:36:39 pm »
Schedule deviation of time from the expected. Ideally, each sample should be in the time position t = i * T0. The graph shows the difference between the time given by the device and the ideal delta t = t - i * Т0
Graph for frequency 1 MHz
 
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Offline Sparky

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #27 on: April 29, 2020, 03:15:26 am »
Schedule deviation of time from the expected. Ideally, each sample should be in the time position t = i * T0. The graph shows the difference between the time given by the device and the ideal delta t = t - i * Т0
Graph for frequency 1 MHz

Thanks MegaVolt.  I really appreciate the testing you are doing on DMM7510 and bringing to light all the peculiarities of the meter, especially related to digitizer mode and aspects of logging/recording data.  I really hope Keithley is paying attention to your findings and follow this thread.

This result is really bizarre.  I wonder if the deviation in sample times is real, or a floating point rounding/truncation error, or something else.  It would be good to have clarification of this issue.  E-Design do you have any thoughts on this?
 

Offline Zucca

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #28 on: April 29, 2020, 09:33:22 am »
A big Thank to MegaVolt also from my side. Well done, I have a 7510 and it is my top DMM on my bench. Unfortunately I do not use it too much.  :horse:

I hope to share my adventures here in the future.
Can't know what you don't love. St. Augustine
Can't love what you don't know. Zucca
 

Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #29 on: April 29, 2020, 10:41:43 am »
Thanks MegaVolt.  I really appreciate the testing you are doing on DMM7510 and bringing to light all the peculiarities of the meter, especially related to digitizer mode and aspects of logging/recording data.  I really hope Keithley is paying attention to your findings and follow this thread.
Thank you for your feedback. I am very pleased to know that someone else needs this. I do not understand Keithley's policy. I could not find contact with people who understand how the device works. Everywhere there are lawyers who say that the device is good and within the specification. Forum forum.tek.com is also silent. Therefore, we can help ourselves.

Quote
This result is really bizarre.  I wonder if the deviation in sample times is real, or a floating point rounding/truncation error, or something else.  It would be good to have clarification of this issue.
Bred O. mentioned an error when switching from one clock domain to another. And what I see in the two down pictures is very similar to this. But what was happening in the upper pictures was a complete surprise for me yesterday. Perhaps this is some kind of software frequency adjustment. For example, under frequent networks or something else ....

I have not yet come up with a good experiment on how to understand if there is a problem with digitization or not.
« Last Edit: April 29, 2020, 10:43:15 am by MegaVolt »
 
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Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #30 on: April 29, 2020, 10:45:35 am »
A big Thank to MegaVolt also from my side. Well done, I have a 7510 and it is my top DMM on my bench. Unfortunately I do not use it too much.  :horse:

I hope to share my adventures here in the future.
Join !!! Maybe when there will be a lot of us Keythley will pay attention to us :))
 
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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #31 on: April 29, 2020, 11:43:45 am »
To me, these kind of effects look like they have their explanation in firmware - So I cant help investigate it directly. What I can do is see if I can get a FW engineer to look at it or an Applications engineer who can spend the time to take a look.
Ask them to look. Thank!!!

Quote
My advice is post these questions and results on the Tek forum and if it doesnt get attention, it is easier to get more people involved to help.
Good! I will add them. I just don’t understand what is the problem and what is not. From the point of view of Keithley.
 
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Offline Sparky

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #32 on: April 29, 2020, 07:25:01 pm »
To me, these kind of effects look like they have their explanation in firmware - So I cant help investigate it directly. What I can do is see if I can get a FW engineer to look at it or an Applications engineer who can spend the time to take a look.
Ask them to look. Thank!!!

Quote
My advice is post these questions and results on the Tek forum and if it doesnt get attention, it is easier to get more people involved to help.
Good! I will add them. I just don’t understand what is the problem and what is not. From the point of view of Keithley.

MegaVolt: can you post a link to your thread on the Tek forum?  I want to track it and post there also.

It appears Keithley are ignoring these issues.    >:(  Why can't they have one firmware guy reading these forums?   :(
 
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Offline MegaVolt

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Re: All about Keithley DMM7510. Bugs and features, recipes, advice, notes.
« Reply #33 on: April 29, 2020, 08:13:08 pm »
MegaVolt: can you post a link to your thread on the Tek forum?  I want to track it and post there also.
https://forum.tek.com/viewtopic.php?f=363&t=142217
https://forum.tek.com/viewtopic.php?f=363&t=142031

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It appears Keithley are ignoring these issues.    >:(  Why can't they have one firmware guy reading these forums?   :(
Bred O. was such a man. But for some reason he stopped writing on the forum.
 
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Offline MegaVolt

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DigiV 100V behaves very strange. Maybe of course these are problems of my device. If someone can check please what your devices show?

At 1000V all this is present but not so bright. And at least fit into the tolerances :))
 
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This effect has improvement in next hardware revision.
I am happy to be able to participate in the free beta test program for future true Keithley customers.  :-BROKE  :clap:  :rant:

I understand the reason for the glitch in the digital track lying next to the divider? Or is it more complicated? Can we get more information to fix the problem ourselves?  :-/O

I understand that the glitches that I saw in the 100V range in the normal measurement modes are of the same nature?
 

Offline MegaVolt

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Different numbers of decimal places depending on the selected screen or the value of a number.
 

Offline Kleinstein

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It is probably the values to show. They seem to use the same number of total digits. So one more digit resolution once below 10 V. For the average the higher resolution may actually make some limited sense.

The peak to peak and StdDev values still have some digits well in the noise / fantasy. It is not a big deal, but ideally there should not be much more digits than actually real. If at the edge one more digit can be good - so the average could get one more digit, while the peak to peak and StdDev case should get less.
 

Offline JxR

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Temperature

* Does not support measurements for Pt1000. No solution.

Both the DMM7510 and DMM6500 should be able to use a PT1000 RTD.  Change 3/4-Wire RTD to "User" and set RTD Zero to 1000.
 
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Offline essele

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I've just posted a couple of bugs around the temp measurement stuff in the Tek forum, so I though I'd add them here for completeness.

(a) Using a thermistor, with 1.7.0e the display reads in kilo degrees ... not very helpful! It was fine in the older firmware.
(b) Using a PT1000 (not sure that's relevant), with 1.7.0e the display reads "-DispNan-" ... graphing is fine, so the value is actually read ok. Haven't tried this in the older firmware.

I'm assuming these are generic temperature display problems with 1.7.0e firmware. Quite how you can release a major firmware release without testing this stuff is beyond me!

I've also found quite a few display issues, but in the scheme of things they seem less important. I must say my first impressions (after only 2 days) is that the hardware seems great, the capabilities (esp the triggering stuff) are superb, but the firmware quality is awful!
 

Offline MegaVolt

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Both the DMM7510 and DMM6500 should be able to use a PT1000 RTD.  Change 3/4-Wire RTD to "User" and set RTD Zero to 1000.
Thank you! I missed that moment.

I've just posted a couple of bugs around the temp measurement stuff in the Tek forum, so I though I'd add them here for completeness.
Thank you!

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(a) Using a thermistor, with 1.7.0e the display reads in kilo degrees ... not very helpful! It was fine in the older firmware.
Yes it is not convenient :(
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(b) Using a PT1000 (not sure that's relevant), with 1.7.0e the display reads "-DispNan-" ... graphing is fine, so the value is actually read ok. Haven't tried this in the older firmware.
This is strange. I connected a 1 kΩ resistor and got the measurements.

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I've also found quite a few display issues, but in the scheme of things they seem less important. I must say my first impressions (after only 2 days) is that the hardware seems great, the capabilities (esp the triggering stuff) are superb, but the firmware quality is awful!
Unfortunately, a number of modes work either with an error or with noise that can hardly be called Gaussian. It seems that tested only some ranges that are really great.
 
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It is probably the values to show. They seem to use the same number of total digits. So one more digit resolution once below 10 V. For the average the higher resolution may actually make some limited sense.

The peak to peak and StdDev values still have some digits well in the noise / fantasy. It is not a big deal, but ideally there should not be much more digits than actually real. If at the edge one more digit can be good - so the average could get one more digit, while the peak to peak and StdDev case should get less.
Yes, I understand. I was uncomfortable getting an extra digit by switching the display. I'd love to have all the numbers on any display.
 
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Ohhhhhhhh !!! I found curious documents. True, they are in Russian.

1. This is a test procedure for the device.
2. Description of the type of measuring instrument.

These documents describe the conditions under which the device is accepted in the state registry of Russia. And the presence of these documents means acceptance by the state as a metrological device. Those. these are the parameters that an independent metrology laboratory checks and guarantees.
 
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Nameplate describing noise quality with shorted inputs in DigiV mode:
 

Offline essele

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(b) Using a PT1000 (not sure that's relevant), with 1.7.0e the display reads "-DispNan-" ... graphing is fine, so the value is actually read ok. Haven't tried this in the older firmware.
This is strange. I connected a 1 kΩ resistor and got the measurements.

That's bizarre ... I've just attached a 1k resistor, using 4W resistance mode it's fine .. I switched to temperature and 4RTD and it said '-DispNAN-', then I went through some of the other transducer devices and it's started working ... very weird.

Just tried a reset and still it appears to be working, although it said "PT100" but was reading a correct value ... so I don't think "reset" actually reset the zero value. That seems like another bug. (This is reproducible -- it's nice to know reset isn't actually a reset!)

Power cycled, and it then seems to be working fine ... PT100 shows "overflow", and then setting the zero value to 1000 works ok.

So I think there's some sequence of events that I went through (I had been using a thermistor before) that got it into this confused state. I've tried going back over some similar steps but can't reproduce it.

Further -- the "zero" setting actually persists if you go from 4RTD to Thermistor and then back to 4RTD even though it says "PT100", so they are not properly resetting values. If you manually select "PT100" then it's ok.

Horrible.
 

Offline MegaVolt

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Unfortunately, this is a frequent occurrence for this device. Any deviation from the correct path can lead to glitches which can be eliminated only by rebooting :(
 

Offline MegaVolt

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The device allows you to set up a fractional aperture; maybe it works; maybe not. I haven’t figured it out yet.
I checked the ability to install a fractional aperture. Unfortunately this does not make sense. In manual mode, the aperture can be a multiple of 1 μs and nothing else.
Fractional aperture only becomes in AUTO mode as I described earlier.

If you want to get a signal suitable for FFT processing, I recommend setting it to either 1µs mode or AUTO mode. In this case, the AUTO mode averages several samples, which improves the signal-to-noise ratio.

Of course, remember that the device has a wide band and if you have not limited the frequency of the signal, then you will get frequency aliasing.
 

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Offline essele

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I've just updated another item I've logged on the Tek support forum...

https://forum.tek.com/viewtopic.php?f=363&t=142266

Its basically saying that, as the graphs start to cover longer time periods, they seem to round the data values and have quite a signficant loss of precision (although there are strange anomalies where this doesn't appear to happen.)

I seem to be talking into a void on the other forum (although did get a response on one of the temperature issues) but thought I'd include it here for completeness.

More detail is in the other forum, but basically I've taken the same (almost) data and bucketed it into 300 buckets (storing min and max) and then plotted using excel, so this is assuming they have 300 pixels to display the data on the screen, and this is roughly what it should look like...

[attach=2]
But on the 7510 it actually looks like this...

[attach=1]

.. clearly awful.
« Last Edit: June 11, 2020, 08:23:55 am by essele »
 
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Offline Kleinstein

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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.

So it looks like another small points of sloppy implemented graphics software.

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.
 

Offline essele

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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.

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!

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.

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.
 

Offline MegaVolt

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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.
 

Offline MegaVolt

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

Offline Kleinstein

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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.
 

Offline MegaVolt

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It is more like odd how they implement this. I could understand 1 µs or 100 ns as the clock used.
I also wonder what the real step is. We’ll have to put on experiments and try to understand how the device works :(
 

Offline MegaVolt

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It is more like odd how they implement this. I could understand 1 µs or 100 ns as the clock used.
Everything turned out to be much simpler. A lot of decimal places is just math. In reality, the integration time directly depends on the 48 MHz oscillator according to the formula N = 300 + k * 400 clock cycles of the oscillator.
This is true for a network frequency of 50 Hz. Does this formula change for the network from 60 Hz I can not check :(

The consequences:
1 NPLC is not exactly equal to 0.02c it can be or 0.0199979167 s
or 0.0200062500 s


And I also understood why the generator is 48 MHz and not 50. 50 MHz is badly divided by 60 :)
« Last Edit: June 26, 2020, 04:02:07 pm by MegaVolt »
 

Offline MegaVolt

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I hurried. The formula 300 + k * 400 applies only to the numbers on the screen. Real accumulation time has a different formula with the same step. Those. what is shown on the screen does not match what is set physically  :palm: :palm:

 I will continue the investigation. Students who programmed this device should be fired :(
 

Offline MegaVolt

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Here is a table of what happens in the device. It's hard for me to explain the logic of what is happening. The selected integration time is not even in the middle of the range.

But eat and plus. If you set the integration time as a multiple of 8.33 (3) ms, then the displayed and real time will coincide.
 

Offline Kleinstein

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The 8.3 µs make some sense as the period of the run-up phase feedback.  One is not limited to these steps, but it makes things easier.   So setting the integration time in ns steps is a bit dishonest.  Only 8.3 µs steps could be slightly limiting in some cases, but is not that bad.
 

Offline MegaVolt

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The 8.3 µs make some sense as the period of the run-up phase feedback.  One is not limited to these steps, but it makes things easier.   So setting the integration time in ns steps is a bit dishonest.  Only 8.3 µs steps could be slightly limiting in some cases, but is not that bad.
Most of all, I don’t like the fact that I have to get these data and numbers myself. I cannot read them in user manual.
 

Offline Kleinstein

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The 8.3 µs make some sense as the period of the run-up phase feedback.  One is not limited to these steps, but it makes things easier.   So setting the integration time in ns steps is a bit dishonest.  Only 8.3 µs steps could be slightly limiting in some cases, but is not that bad.
Most of all, I don’t like the fact that I have to get these data and numbers myself. I cannot read them in user manual.
I absolutely agree with that.

With modern instruments the manuals get increasingly confusing and the specs get unclear, missing details or the relevant part to compare different products. For the DMM7510 I can absolute understand that they don't want to show the 100 PLC noise. So the specs tend to leave out the weak points.

In part this is because of the flood of new features and options and planed additions to the software.  So they have to release a manual before the software is really ready (if it ever gets  :horse:). Fixing the bugs is usually slow and updating the manuals is usually even slower. When writing instructions one tends to focus on the new / special features, so one may miss one the classical important part.

The manual is already quite long and is still missing quite a bit on app programming.
 

Offline MegaVolt

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Yes that's right :(

At the expense of noise in my opinion the data is outdated. I'm busy measuring noise right now. Soon I will share the results.
 

Offline MegaVolt

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I found that DCV noise in the 0.1V range changes little until the integration time is 0.007s
It became interesting to me how this noise looks and it looks like a certain periodic signal :(

Aperture = 0,000475 s
 

Offline MegaVolt

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During the night I collected more data and there is a similar generation for long integration times. For example, here is a picture for NPLC = 8.5. And similar pictures for all times of integration of a kind 5.5; 6.5; 7.5;
It looks like a network frequency.
 

Offline Kleinstein

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Using things like 7.5 PLC makes the meter sensitive to mains hum (50 Hz, but not 100 Hz). Due to the time needed for rundown, there is a beat frequency and this would be visible. So the amplitude seen here is likely from the 50 Hz hum. This is why the preferred modes are integer PLC numbers.

For the much faster test in the digitizing mode one may see residues of ripple from an chopper OP too.
 

Offline MegaVolt

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Using things like 7.5 PLC makes the meter sensitive to mains hum (50 Hz, but not 100 Hz). Due to the time needed for rundown, there is a beat frequency and this would be visible. So the amplitude seen here is likely from the 50 Hz hum. This is why the preferred modes are integer PLC numbers.
Yes, I understand this feature of integrating ADCs. Everyone has it and it seems even 3458a judging by the picture in the application.
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For the much faster test in the digitizing mode one may see residues of ripple from an chopper OP too.
You express your thoughts very briefly. And I often cannot understand because the translator often loses some of the meaning. Could you write a little more about the idea of this test. If we talk about the noise that I see with DigiV, then it does not look like 50Hz. I see 14KHz noises I wrote about them above.
 

Offline MegaVolt

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Here are the noise graphs. For the rms value and for the constant component (Vm0).

For the DC component and the 0.1 V range, there are curious points of 0.1; 0.35; 0.6 NPLC they give a big shift but in fact there is a periodic process that is longer than 1000 samples. Therefore, we see the error of expectation because we consider it for part of the period.

I attached a picture taken for 100 thousand counts.
 
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Offline MegaVolt

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Looking at the similarity of the 1 V and 100 V graphs, there is a suspicion that they divide 100V by 1000 and then process it as a 1V signal.

For channels 1V and 0.1V, 5 NPLC is really the best, followed by 1 and 2 NPLC. I believe in these ranges software averaging of samples with 1 NPLC will give good results.

I'll check it a little later.
 

Offline Kleinstein

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Using a divide by 100 and than use the 1 V range is the normal path for the 100 V range in many meters, so no surprise here.

The extra periodic background looks strange with steps in frequency. The frequency is likely some beat frequency with mains hum. With some extra time for signal processing / run-down 10 readings at 0.1 PLC would likely take a little longer than 20 ms and thus some phase shift with every reading. The mains frequency will also have an effect, but I doubt the more discrete frequency ranges would be due to the mains frequency.
The periodic signal would also cause the plateau at low PLCs for the 0.1 V range, as different PLC settings would mainly effect the frequency and less the amplitude.
 

Offline MegaVolt

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Using a divide by 100 and than use the 1 V range is the normal path for the 100 V range in many meters, so no surprise here.
I understand the essence of this decision. One divider instead of two. This saves 1 precision resistor. And this is expected in a budget multimeter. But in 7.5-digit, I thought there would be no such savings. Especially considering that the amplifier standing on the 1V input spoils the noise characteristics.
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The extra periodic background looks strange with steps in frequency. The frequency is likely some beat frequency with mains hum. With some extra time for signal processing / run-down 10 readings at 0.1 PLC would likely take a little longer than 20 ms and thus some phase shift with every reading. The mains frequency will also have an effect, but I doubt the more discrete frequency ranges would be due to the mains frequency.
The periodic signal would also cause the plateau at low PLCs for the 0.1 V range, as different PLC settings would mainly effect the frequency and less the amplitude.
Forgot to add. If you disable AZ, then the cunning envelope disappears. And there remains just a certain frequency with a constant amplitude. The signal does not become smaller in amplitude but looks prettier.
 

Offline Kleinstein

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Normally the amplifier only add a little noise to the 1 V range. Much of the noise is often still from the ADC (and the references of cause). So the way with only one divider does not add that much noise.  The standard high voltage divider are this way, so even 8 digit meters like 3458, Datron 1281 and Keithley 2002 use only 1 divider, though here it may actually help to have 2 divider settings. Switching off the 1:10 divider may however need a relay for switching (or switch at the low side and this a variable impedance), and this can add more trouble than using just 1 divider.

Forgot to add. If you disable AZ, then the cunning envelope disappears. And there remains just a certain frequency with a constant amplitude. The signal does not become smaller in amplitude but looks prettier.
That is interesting: so the low frequency part is more like an aliasing of the higher frequency part.

The very fast readings well below 1 PLC are often used without auto zero, as this about speed and not so much about accuracy.
 
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Offline MegaVolt

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First impressions:

Fixed working with memory. For the first time I was able to allocate a buffer for 8.3 million samples.
But unfortunately, as before, it cannot be filled with data during digitization. Somewhere after 4 million there is a pause in filling the buffer :(

Kilo degrees left.
 

Offline MegaVolt

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I updated the new version and after ACAL I found an additional zero offset of 200 ... 300 nV.
It was in the region of 300-400 became 500-800 ....

Does anyone have a similar effect?

The only thing that I made a mistake and confused ACAL after flashing without turning off the device. That is, he rebooted himself, but I did not remove the power completely. Then I found that the device was not behaving quite correctly (for example, I could not switch the input impedance) and turned off the power. After turning on and re ACAL, I see the same shift :(

Perhaps I ruined something. Or in the new firmware there were some changes about which were not said in the description :(
 

Offline E-Design

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I updated the new version and after ACAL I found an additional zero offset of 200 ... 300 nV.
It was in the region of 300-400 became 500-800 ....

Does anyone have a similar effect?

The only thing that I made a mistake and confused ACAL after flashing without turning off the device. That is, he rebooted himself, but I did not remove the power completely. Then I found that the device was not behaving quite correctly (for example, I could not switch the input impedance) and turned off the power. After turning on and re ACAL, I see the same shift :(

Perhaps I ruined something. Or in the new firmware there were some changes about which were not said in the description :(

Hi Megavolt, do you have a low thermal short for when doing zero calibration? Thermal effects from metal of the short and environment can cause voltage gradients of 100+ nV How much thermal settling time? No airflow blowing on the instrument? These are some of the considerations for you. Even a brief power cycle is enough to upset the offset 100nV due to the internal temperature change and re-settling.

Also there will not be any undocumented firmware changes that you didnt see in the description in case you worry about it. If firmware makes a change to calibration or how the measurements are built, it will be described there.
The best way to predict the future is to invent it.
 

Offline MegaVolt

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Hi Megavolt, do you have a low thermal short for when doing zero calibration?

I have a special shorting from Keithley. I bought it specifically so that I had something to answer this question :)))

The device stood and carried out automatic measurements for several days. With installed short Keithley. Then I interrupted the measurement. Updated firmware and continued measurements. After that, a clear step appeared on the chart before and after the update. (I will add a graph in the evening)
 
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Offline MegaVolt

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Left - 5 day test
Right - 3 day test after update.
 

Offline Kleinstein

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Updating the firmware may imply running an ACAL. This alone could change the offset a little.
 

Offline MegaVolt

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Updating the firmware may imply running an ACAL. This alone could change the offset a little.
For two years I played with the device and started ACAL. Mixing was kept at 300-400nV very stable.

I assume that it is possible that ACAL can start after updating the firmware without turning off the power, but it doesn’t work as intended. It is not very clear why repeated ACAL does not return anything :(
 

Offline E-Design

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Updating the firmware may imply running an ACAL. This alone could change the offset a little.
For two years I played with the device and started ACAL. Mixing was kept at 300-400nV very stable.

I assume that it is possible that ACAL can start after updating the firmware without turning off the power, but it doesn’t work as intended. It is not very clear why repeated ACAL does not return anything :(
Updating the firmware requires a reboot which isnt as thermally upsetting as a power cycle but it still might make a small shift. I would expect though, the zero to eventually return to its previous value after some time.

An ACAL however, will rebuild the zero measurement and now becomes dependent on how good of short and thermally stable you can make at the terminals.. It will in general, end up being slightly different.

For your thermal short, check the orientation of it. It is not thermally symmetric. Rotate it and let unit sit for > 1 hour, you will see a shift. It is designed for stable HI-LO but as you can see there is also a SHI-SLO and the two connect. Anyways, the orientation is another variable. Also, you didnt say, are there air currents or other instrument nearby creating less stable environment. I couldnt see your picture because its only the graph not the instrument.
The best way to predict the future is to invent it.
 

Offline MegaVolt

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I carefully checked the captured data and found this jump before flashing. I apologize for the uproar. I was wrong.
Unfortunately, I cannot find an explanation for this phenomenon other than a decrease in temperature by a couple of degrees.
But this phenomenon is definitely not related to firmware.
The graph shows data with NPLC = 5 and averaging filter = 12
 
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Offline eplpwr

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Temperature display fixed in FW 1.7.3c
« Reply #81 on: July 24, 2020, 03:52:31 pm »
Two days ago I filed a support case with Tek regarding the temperature in Celsius being shown as kilo-degrees.

Today I received a FW version 1.7.3c and can report that my specific problem is fixed. From what Tek/Keithley wrote, is seems like this version is very close to being published on their site.  :clap:

[attach=1]

Unfortunately, I didn't get any release notes (PDF file), just an .upd file that flashed without problems, so I don't know what other fixes are in there.

Best regards,

eplpwr

 
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Offline MegaVolt

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Re: Temperature display fixed in FW 1.7.3c
« Reply #82 on: July 24, 2020, 09:37:53 pm »
Two days ago I filed a support case with Tek regarding the temperature in Celsius being shown as kilo-degrees.
Tell me through which communication channel did you get such a quick response?

Quote
Today I received a FW version 1.7.3c and can report that my specific problem is fixed. From what Tek/Keithley wrote, is seems like this version is very close to being published on their site.  :clap:
Can you share this firmware? Or is she under NDA
 

Offline eplpwr

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Re: Temperature display fixed in FW 1.7.3c
« Reply #83 on: July 25, 2020, 08:56:21 am »
Tell me through which communication channel did you get such a quick response?

I used the support form on tek.com.
 
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Offline MegaVolt

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The firmware actually appeared on the site
https://uk.tek.com/digital-multimeter/dmm7510-software/model-dmm7510-firmware-revision-173-and-release-notes

But I can't download it because: "In compliance with U.S. Government regulation, Tektronix is required to review all software download activity. This process may take up to one U.S. business day and you will be notified when the process is complete. We apologize for any inconvenience."  :palm: :palm: :palm:

I'll wait for the day :))))
 

Offline MegaVolt

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I cannot download either the new or the old update. Did anyone manage to download the new update? Can he put it somewhere?
 

Offline coromonadalix

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Their website works awfully,  they messed up my registration, lots of lags ?? in my case.  To force people to register   pfffffff

heres your file   v 1.73

https://gofile.io/d/KhSSup

around 7.2 megs

Release note pdf  added
« Last Edit: July 26, 2020, 08:20:12 pm by coromonadalix »
 
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Offline coromonadalix

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Version 1.7.3 provides fixes and enhancements.
CRITICAL FIXES

Reference number: NS-1908
Symptom: Changing an annunciator setting (such as auto zero or filter enable) on the
Settings or Calculations screen is not reflected in the Home screen
annunciators.
Resolution: This issue has been corrected.

Reference number: NS-1909
Symptom: Temperature readings are shown as k (for kilo) degrees Celsius,
Fahrenheit, or Kelvin instead of degrees Celsius, Fahrenheit or Kelvin.
Resolution: This issue has been corrected.

Reference number: NS-1927
Symptom: The LXI identification web page shows the incorrect LXI version and web
page links.
Resolution: This issue has been corrected.


ENHANCEMENTS

Category Remote commands

Reference number: NS-1931: Added a TLS (transport layer security) option when using the
tspnet.connect() command.
connectionID = tspnet.connect(ipAddress, portNumber,
 initString, useTLS)
ipAddress: A string that indicates the IP address or host name to
connect to.
portNumber: Default 5025.
initString: Sends a string to ipAddress.
useTLS: 0 or 1;
0: Do not use TLS with the connection (default)
1: Use TLS with the connection.
When useTLS is set to 1, the instrument negotiates the security protocol
when connecting to the host or IP address that is used. This security
protocol is used when using tspnet.write() to send data or
tspnet.read() to receive data.

Version 1.7.3 Release DMM7510 7½ Digit Graphical Multimeter Version 1.7.3 Firmware Release Notes
DMM7510-FRP-V1.7.3 June 2020 Page 5 of 49
The following is an example of how to use a host name with the TLS
option:
connectionID = tspnet.connect(“hostname.domain.com”,
 443, “”, 1)

Category Remote commands

Reference number: NS-1960: The localnode.gettimewithfractional() TSP
command is available to retrieve the number of seconds elapsed since
January 1,
 


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