Author Topic: New Keithley DMM6500 and now DAQ6510  (Read 296752 times)

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Offline hwj-d

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #350 on: January 22, 2019, 11:10:07 pm »
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Ahhh, I see what you mean, try clicking the page number instead of the function name, does that work?

Thanks Brad, that's it. Besides this big "fake"-hyperlinks i didn't register the clickable page numbers at all.  ???

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All those links will be fixed in the next manual update in March.

 :-+
 
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Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #351 on: January 22, 2019, 11:18:52 pm »
The 7510 has different specs for its timestamps when digitizing than the DMM6500/DAQ6510, (search for "timestamp" in the 7510 datasheet to see the lines I'll be mentioning) the timestamp resolution is 1ns for standard buffers so that's why you're seeing that small variation, the actual difference is probably less.  The timestamp accuracy is spec'd to "20ns between adjacent readings".  What it means is there's 20ns of uncertainty between adjacent readings, so two readings could potentially be 40ns apart, as you're seeing.
Oh yes :( I don't read the fine print well.

OK :( +/- 20 ns meet specifications. But 100 ns is already beyond the specification. Plus in DCV modes, the spread is more than 100ns :(

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The reason for this discrepancy, incidentally, is that the 7510 uses different clocks for timestamps and digitized readings that sync up every so often.  In actuality, the digitized readings are probably much closer together than what the timestamps say, it's the timestamps with the uncertainty, not the readings.
Is there any chance that this will be fixed in 7510? After all then all sense of timestamp is lost.

Plus it seems to me that the synchronization of two hours can explain a single time failure. But on the chart I see triple crashes. And in some modes, I can find more bad samples.

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Try this script I'm attaching (same deal, change .txt to .tsp and run on the instrument), it's the same one I described in this message.  It'll take 100 readings on the 10V DCV range each 1s apart, just to make sure you're not missing anything.  Like I said, I saw <100ns difference between timestamps, you should see somewhere around that.
I ran this script from the device (just fixed BLOCK_MEASURE_DIGITIZE on BLOCK_MEASURE for the second block). And I got a constant error of 17.5 μs on each measurement and the peak to peak spread is the peak of 2500 ns.

Data in the attachment.
 

Offline Brad O

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #352 on: January 23, 2019, 06:50:42 pm »
The 7510 has different specs for its timestamps when digitizing than the DMM6500/DAQ6510, (search for "timestamp" in the 7510 datasheet to see the lines I'll be mentioning) the timestamp resolution is 1ns for standard buffers so that's why you're seeing that small variation, the actual difference is probably less.  The timestamp accuracy is spec'd to "20ns between adjacent readings".  What it means is there's 20ns of uncertainty between adjacent readings, so two readings could potentially be 40ns apart, as you're seeing.
Oh yes :( I don't read the fine print well.

OK :( +/- 20 ns meet specifications. But 100 ns is already beyond the specification. Plus in DCV modes, the spread is more than 100ns :(
100ns fits within the specs if your buffer is longer than 2s.  In non-digitize measurements, the timestamps aren't spec'd but they generally match the behavior of the digitize function timestamps, so longer buffers could see jumps like that.

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The reason for this discrepancy, incidentally, is that the 7510 uses different clocks for timestamps and digitized readings that sync up every so often.  In actuality, the digitized readings are probably much closer together than what the timestamps say, it's the timestamps with the uncertainty, not the readings.
Is there any chance that this will be fixed in 7510? After all then all sense of timestamp is lost.
Honestly, it's not very likely.  There simply aren't enough people that need the kind of timestamp resolution or accuracy you're talking about to justify the change.  We changed the way timestamps are handled in the 6500/6510 to improve accuracy and resolution, but the 7510 is unlikely, at this time, to receive changes to how it handles them. 

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Try this script I'm attaching (same deal, change .txt to .tsp and run on the instrument), it's the same one I described in this message.  It'll take 100 readings on the 10V DCV range each 1s apart, just to make sure you're not missing anything.  Like I said, I saw <100ns difference between timestamps, you should see somewhere around that.
I ran this script from the device (just fixed BLOCK_MEASURE_DIGITIZE on BLOCK_MEASURE for the second block). And I got a constant error of 17.5 μs on each measurement and the peak to peak spread is the peak of 2500 ns.

Data in the attachment.
Wait, is this buffer from the 7510 too? BLOCK_MEASURE is depreciated in the DMM6500/DAQ6510 in favor of BLOCK_MEASURE_DIGITIZE.  I'm assuming everything in this thread is about the 6500/6510 unless you tell me otherwise and the 7510 behaves differently enough that I need to know which one you're using if you want good answers, also so that I can properly replicate and log issues. 

That said, I could replicate your graph with the 7510 and that amount of timestamp drift is surprising to me and the firmware engineers.  I've logged an issue to look into this and see what's happening.  From the script I gave you, there's a couple places that could cause the delay offset (which is not present in the 6500) and jitter (which is much less in the 6500) worth looking at.

 
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Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #353 on: January 23, 2019, 07:13:02 pm »
Honestly, it's not very likely.  There simply aren't enough people that need the kind of timestamp resolution or accuracy you're talking about to justify the change.  We changed the way timestamps are handled in the 6500/6510 to improve accuracy and resolution, but the 7510 is unlikely, at this time, to receive changes to how it handles them.
Very sad. I thought a higher grade device deserves greater precision in the first place.

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Wait, is this buffer from the 7510 too? BLOCK_MEASURE is depreciated in the DMM6500/DAQ6510 in favor of BLOCK_MEASURE_DIGITIZE.  I'm assuming everything in this thread is about the 6500/6510 unless you tell me otherwise and the 7510 behaves differently enough that I need to know which one you're using if you want good answers, also so that I can properly replicate and log issues. 

That said, I could replicate your graph with the 7510 and that amount of timestamp drift is surprising to me and the firmware engineers.  I've logged an issue to look into this and see what's happening.

Yes, I'm talking about the 7510. I understand that there is a separate topic for the bugs 7510. But I'm not sure that these are bugs. By this, I can write here? And I will attribute that it is about 7510.

Is there a more accurate script that takes into account the features of the 7510?

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From the script I gave you, there's a couple places that could cause the delay offset (which is not present in the 6500) and jitter (which is much less in the 6500) worth looking at.
If possible, tell us more about it. I want to understand my device by myself. So that I can write good scripts without distracting you from work.
 

Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #354 on: January 30, 2019, 09:15:31 am »
Brad O can I ask you a couple more questions about 7510?

1. DataSheet promises 140,000 measurements per second via LAN (measurement + time). So far I was able to get a maximum of 20,000. 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?
« Last Edit: January 30, 2019, 02:35:47 pm by MegaVolt »
 

Offline cozdas

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #355 on: January 31, 2019, 10:59:38 am »
I received my DMM6500 two days ago and since then I was playing with it and reading the reference manual. I'm very pleased with this -my first- bench multimeter. It's very versatile and very flexible with the scripting capabilities and extensive settings (probably pros are used to it but that's very impressive for me, who only used hand-held DMMs so far).

I hit several bugs while playing with it (yes, novice users are the best beta testers). I was able to crash it multiple times usually while playing with the graphing options. Graphing is nice and being able to graph the buffer extra values is a nice touch. One glitch is that even if you plot the extra values in the buffer, the stats panel in the graph window still shows the stats of the main readings in the buffer. This becomes confusing especially when you graph both the main and the extra values of the same buffer in the same plot.

One missing feature is the ability to display the reference and input voltages while taking the "DC voltage ratio" measurements: you can only display the ratio. You can see the input voltage by setting the secondary panel to DC voltage, but the reference voltage at the sense port can not be displayed in realtime anywhere on the screen (Input voltage is also stored in the "extra value" column, so can be seen in the table view). I think Keysight 34465A can display both voltages in realtime and this would be a nice addition for a future DMM6500 firmware. I don't think there is a hardware limitation for this useful feature, they just need to design the UI for it IMHO.

I wanted to check and compare the noise levels of two voltage references I built, one with LM399 and one with REF 102. So I took this as a challenge to learn the scripting capabilities of the DMM and implemented a simple script which computes the sense voltage from the ratio and the input voltage from the extra value field of the buffer and display it on the user screen. I also wanted to be able to graph the two channels. After spending couple of hours with the reference manual, I was able to kinda implement this missing feature. At the end, as a bonus, through a small hack I was able to upgrade the main display resolution to 8.5 digits! (sorta, see the images)  :-/O

Now that I have two voltages measured at the same time, I think I should be able to extract the noise of the DMM's internal voltage reference by cross-correlating the two channel values, and thus be able to characterize the noise of the two DUIs much better. But that's another project.

So far very happy with the device.

- Attachments and other options
« Last Edit: January 31, 2019, 07:42:10 pm by cozdas »
 
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Offline hwj-d

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #356 on: January 31, 2019, 12:52:15 pm »
Wow, that are nice hacks.  :-+
At first I had also some bluescreens, but that hasn't happened since.
Yes, the gui can be improved in some areas. Especially for reference measurements, the reference voltage is very small and hidden next to the REL button on the adjustment screen. This belongs on the statistics screen.

Do you want to share your scripts, please? I'm very interested!

Another question, did you get a detailed calibration report, as it should be for such an instrument?

And welcome to the forum.  :)
 

Offline TiN

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #357 on: January 31, 2019, 05:57:30 pm »
After spending couple of hours with the reference manual, I was able to kinda implement this missing feature. At the end, as a bonus, through a small hack I was able to upgrade the main display resolution to 8.5 digits! (sorta, see the images)  :-/O


Welcome, cozdas. Nice hanks, but that's 7.5 digits  ^-^.
Interesting to see more, keep up good work.
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Offline Evodad

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #358 on: January 31, 2019, 07:50:02 pm »
Hi all !

New to this forum and also a new owner to a DMM6500.

I had a really old Keithley for many years until it broke and I have missed it since. My Flukes does not really match up.
That is the reason I bought this DMM6500 after finding this thread. As a general DMM I really like this Instrument but I find
the added Graphical presentation lacking in how things are presented and the menues.

Especially in the Digitizing mode, why is there no SET (Settings Tab) among the Graph Tabs ? You have to go through multiple
steps to set sample rate and and the number of samples ? The Buffer settings could be there as well  >:D

Yes, a couple of Blue Screens and some Bugs here and there, but it's liveable, though, the biggest design flaw is the FAN !
(Personal opinion  ;))

Why should you need a Fan? This is a professional working tool, having to listen to a Fan (all day) is fatiguing.
Would it be possible to have a low speed mode or even being able to turn it of, maybe with some penalties is performance?

Yes, turning mostly to Brad O here.

Kind regards, P
« Last Edit: January 31, 2019, 07:55:23 pm by Evodad »
 

Offline MikeP

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #359 on: January 31, 2019, 08:03:47 pm »
Nice hanks, but that's 7.5 digits  ^-^.


 I was surprised when I first saw the calibration data. Many values contain eight digits. I asked Brad - how is this possible?! Brad said: yes, the multimeter can return such values, but not on the display.
 It is necessary to find out - is there any sense in these numbers.
 
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Offline Kleinstein

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #360 on: January 31, 2019, 08:41:57 pm »
The digits beyond about 7 digits have no real value. The noise and INL error of the DMM is likely larger than that. From some point it's also just a floating point number scaling a limited resolution value. So there will be some steps no to allow all possible values in between. 

There is a little value to the 7 th digit in that one can see drift direction a little earlier and does not get extra rounding or quantization error. So it's OK for the computer to use those extra digit(s), but when writing things down by hand it's usually not worth it.
 

Offline cozdas

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #361 on: January 31, 2019, 10:05:51 pm »
Do you want to share your scripts, please? I'm very interested!
Another question, did you get a detailed calibration report, as it should be for such an instrument?
And welcome to the forum.  :)
I can share the script, sure. But before exposing my trick to display 7+ digits I want to make sure that spying( :) ) Keithley guys won't have this "feature" fixed in the new firmwares ;)

I received a "Traceable calibration certificate" with a certificate no but I don't know where to find the detailed report.

I was surprised when I first saw the calibration data. .... the multimeter can return such values, but not on the display.
How did you access the cal data?

Nice hanks, but that's 7.5 digits  ^-^.
You are right that it doesn't show 8.5 digits, but I can see 8 digits in the big display mode (first digit can be 9). Let's call it 8.0 digits. Deal? :P

Yes, a couple of Blue Screens and some Bugs here and there, but it's liveable, though, the biggest design flaw is the FAN !
(Personal opinion  ;))
Totally agree. I'm very sensitive to noise and thus I replaced the fans of my NAS, my lab power supply and while building my beefy 32-core dual xeon system I made sure the fans are super silent. This device is the biggest noise maker in the entire house now. I'm tempted to replace that fan with a silent Noctua fan but probably won't touch it while it's newly calibrated.

The digits beyond about 7 digits have no real value. The noise and INL error of the DMM is likely larger than that. From some point it's also just a floating point number scaling a limited resolution value. So there will be some steps no to allow all possible values in between. 
There is a little value to the 7 th digit in that one can see drift direction a little earlier and does not get extra rounding or quantization error. So it's OK for the computer to use those extra digit(s), but when writing things down by hand it's usually not worth it.

I'm pretty sure that the internal representation is 64-bit floating point: I'm seeing value differences that require at least 42 bit mantissa, way smaller than the 32-bit float's 23-bit mantissa can provide. As you said that extra resolution won't provide extra accuracy or even precision for sure. But I think there is a use for that in some specific scenarios like the one I'm working on. I'm not very sure about how the sense and input terminals are actually digitized internally for the volt ratio, but looking at the graph I can definitely see some concurrent jumps in both channels, which are probably from the DMMs internal noise, and I see jumps only on a single channel, which suggests that coming from the DUT. So with some digital signal processing I can hopefully extract some stats for those 3 devices separately. We'll see.

With large NPLC and filtering values I can get a very stable 7th digit. Although a single ADC output won't have a useful info in the 7th digit, with averaging I think 7th digit is usable for some limited cases. I can see the direction of the change as you suggested in the 8th digit (probably showing the direction of the low freq noise).

I also realized another small bug: when you export a buffer to CSV, the "extra" channel isn't written with enough digits. Main reading values contain full 64bit float though. (see the images)
Code: [Select]
9.999981650865,Volt DC,...,6.984300,Volt DC,
9.999980233491,Volt DC,...,6.984298,Volt DC,
9.999979931922,Volt DC,...,6.984298,Volt DC,
As a workaround I can change my script to write the second voltage to a separate buffer instead of storing in the extra channel of the same buffer but It'd be waste of space unnecessarily.


And thanks for the warm welcome messages :)
« Last Edit: January 31, 2019, 10:16:50 pm by cozdas »
 
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Offline hwj-d

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #362 on: February 01, 2019, 12:04:05 am »
Hi Evodad,

welcome to the forum too.  :)
 

Offline hwj-d

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #363 on: February 01, 2019, 01:02:24 am »
I can share the script, sure. But before exposing my trick to display 7+ digits I want to make sure that spying( :) ) Keithley guys won't have this "feature" fixed in the new firmwares ;)
Then please PM it to me. Please also the trick to display 2nd trace.  :)
Maybe you're importing the data by simulating a scanner channel?

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I received a "Traceable calibration certificate" with a certificate no but I don't know where to find the detailed report.
Then you didn't got it. Look at MikeP's earlyer Post, he published his.

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I'm not very sure about how the sense and input terminals are actually digitized internally for the volt ratio, but looking at the graph I can definitely see some concurrent jumps in both channels, which are probably from the DMMs internal noise, and I see jumps only on a single channel, which suggests that coming from the DUT. So with some digital signal processing I can hopefully extract some stats for those 3 devices separately. We'll see.
That's my idea too. Some of my refs sometimes tend to go crazy. And i don't know, is it the dmm. If they do it the same time, I'm one step further. And yes, there is popcorn noise...

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With large NPLC and filtering values I can get a very stable 7th digit. Although a single ADC output won't have a useful info in the 7th digit, with averaging I think 7th digit is usable for some limited cases.
I use the 7th digit from cvs-protocoll, to build my traces with Libreoffice.
« Last Edit: February 01, 2019, 01:09:16 am by hwj-d »
 
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Offline cozdas

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #364 on: February 01, 2019, 01:23:31 am »
Well multiple people asked for the script already so I decided to release it. It's nothing fancy actually; just read the ratio buffer and compute the "input" voltage from "ratio" and "reference" values then place them in another buffer(s). Extra digits were just side effect. Just promise me that if Keithley fixes the "feature" then help me push back :D

Script is here: https://github.com/cozdas/DMM6500/

If you are not familiar with the TestScriptBuilder, you can just grab the cozDualVolt.tsp file and place it in a USB stick. You should be able to run it on the DMM.

Enjoy.
 
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Offline hwj-d

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #365 on: February 01, 2019, 01:30:46 am »
Ok, I see you. You got a double thanks. ;)
Btw, nice Coyote  ;)
 

Offline cozdas

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #366 on: February 01, 2019, 11:58:27 am »
Fun with 10k precision resistor, 4-write relative measurement in relative mode. Not very useful but hey! :P

 

Offline hwj-d

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #367 on: February 01, 2019, 12:59:18 pm »
You can right click virtual front panel for screen only  :)
 

Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #368 on: February 01, 2019, 01:11:28 pm »
I tried to run the virtual panel on the phone. It turned out not very well: (
 

Offline jancumps

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #369 on: February 01, 2019, 02:05:23 pm »
Hey @analogRF I don’t know if you’ve bought a 6500 yet, but I put together that Probe hold script for you and anyone else (@MikeP).  Also see the end for news on firmware.

It uses the App interface of the DMM so it behaves a little differently from a normal script.  I put together some info below.

INSTRUCTIONS:
1.   Download the attached file and change the .txt ending to .tspa
2.   Make sure your DMM’s command set is set to TSP in MENU > Settings
3.   Put the script on a USB drive and insert into the DMM
4.   Press the APPS key and go to the USB tab
5.   You can either run the script here, or save it to local memory first (it will be added to local memory automatically)
6.   Click Run

....
I like this script. When working in DCV mode, it helps to put the meter input impedance to 10 MOhm. In high impedance mode the probes can float above the threshold voltage by just laying on the table or being unconnected, in your hand, and add unwanted entries in the hold table when moving from testpoint to testpoint.

One thing I noticed is that the threshold label says that anything above it  is captured, but if you enter 2 V, also -2.5 V is captured. Not an issue, but it seems contrary to what's labeled.

 
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Offline hwj-d

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #370 on: February 01, 2019, 02:28:19 pm »
BradO tolds me, that they are developing an interactive editor with syntax highlighting-completion and debugging possibilities for online tsp-scripting.
That's good news to comfortable develop such things for own needs.  :-DMM
« Last Edit: February 01, 2019, 02:30:00 pm by hwj-d »
 

Offline MikeP

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #371 on: February 01, 2019, 09:24:27 pm »

This device is the biggest noise maker in the entire house now. I'm tempted to replace that fan with a silent Noctua fan but probably won't touch it while it's newly calibrated.


Try to block the holes in the case. You will immediately see the results on the display.
 

Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #372 on: February 01, 2019, 10:08:48 pm »
Brad Oh, I will continue to ask about the 7510?

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.
« Last Edit: February 01, 2019, 10:12:19 pm by MegaVolt »
 

Offline jancumps

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #373 on: February 01, 2019, 10:26:34 pm »
Quote
I will continue to ask about the 7510
Can you open a 7510 thread? These posts about another instrument in they DMM6500 and DAQ6510 thread are confusing.
 
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Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #374 on: February 03, 2019, 10:58:50 am »
Can you open a 7510 thread? These posts about another instrument in they DMM6500 and DAQ6510 thread are confusing.
You can do a lot of thread. But Brad O is one. And it seems to me that the chance to get an answer is higher if you write in one topic. Plus the software control of these two devices is very similar. If possible, I would like to stay in this thread.
 


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