Author Topic: New Keithley DMM6500 and now DAQ6510  (Read 103406 times)

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Offline cozdas

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #650 on: July 31, 2019, 07:42:35 am »
Fluke 8842A: -35mV for 1A in all ranges.
 
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Online The Soulman

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #651 on: July 31, 2019, 08:57:07 am »
I tried two other meters:

Keithley 2015 THD: 14.5mV offset is observed on all scales. It is constant.
Keysight 34470A: 75mV offset is observed on all scales. It is constant.

I can try this on several other models (Keysight, Rigol, Siglent, etc.) if you guys really want to see.  :-//

Perhaps you can do a video where you hunt down the cause of this offset and explain the reason why it is there.
Tell about proper measurement techniques etc.
 
On the keithley it would be interesting to see where that jump in the 100 Volt range is coming from.

 
 

Offline KedasProbe

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #652 on: July 31, 2019, 03:32:16 pm »
Hi,

I made another script to make things easier:
When you have a sensor output 0-10V or 4-20mA or ... you usually want to see the right values live.
You can enter m and b of  Y=m.X+b in the menu but usually your sensor documentation isn't m and b but 2 points of that line, so you can take your calculator... but the DMM6500 is a calculator so why not let it do it for you, hence this script enter two points and it will update m and b for you.

It also allows to set a unit to change 'X' I don't think you can do that in the menu, unfortunately limited to 2 char.
(this avoids confusion)

No sound video example:


Script:
https://github.com/Ken26M/keithley/blob/dev/Instrument_Examples/DMM6500/LinearConversion.tsp


edit: If you just want to do a current measurement and convert your resistor voltage drop to current, just enter
X1=0 and Y1=0  (no current if no voltage is present)
X2 = the known resistor value (volt but think ohm)
Y2=1 (1A if voltage = resistor value)
« Last Edit: August 03, 2019, 10:24:01 am by KedasProbe »
Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 

Online Kleinstein

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #653 on: July 31, 2019, 03:44:28 pm »
The offset comes from the resistance from the banana plug at the common input to the internal zero point, that is usually at the lowest shunt. This includes the double plugs, so it's not even all from the meter. It is a pronciple problem to use the same terminal for a high current and precision voltage - these don't go together. So the cross coupling is not a surprise at all.

A solution for the problem could be using the Ohms sense terminal at least for the common side of the voltage measurement. Depending on how the 4 wire ohms is implemented this could be relatively easy and more like just a software thing. As the meter supports ratio measurements via the Ohms sense terminals it should be possible to use them, from the HW side - though one may still need an external link. The difference between the voltage negative side and current terminal is limited, but should be good enough for the offset.

The higher shift for the 100/1000 V ranges is likely due to the point where the divider is connected. If the shift adds after the divider the number gets high.
 

Offline lukier

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #654 on: July 31, 2019, 09:44:37 pm »
I've tested most of my meters. Sourced 1A into the current terminals, confirmed by switching to the current function and then switched to DCV and went through the ranges.

Only DMM6500 has this problem, above 10V range 25mV becomes 2.5V.
Other DMMs (2 x 3458A, K2001, K2015, 34401A) usually on lower ranges behave as nothing is connected (collecting charge) and on higher ranges are close to zero, both are to be expected.
 
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Offline maxwell3e10

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #655 on: July 31, 2019, 10:00:53 pm »
Did you short out (or put some resistor) across the voltage inputs of the meters? Otherwise, they do read zero but its not an accurate representation of what happens if some voltage source is connected.
 

Offline lukier

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #656 on: July 31, 2019, 10:47:31 pm »
Did you short out (or put some resistor) across the voltage inputs of the meters? Otherwise, they do read zero but its not an accurate representation of what happens if some voltage source is connected.

No, I forgot to short them, hence why on low ranges they were collecting charge (GOhms). But they behaved exactly the same when nothing is connected (also to current input) so I assume it is fine. DMM6500 was also tested the same way and yet it showed 2.5V out of nowhere, on 10MOhm ranges that don't accumulate that much charge.
 

Offline Mike G

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #657 on: August 01, 2019, 04:47:31 am »
I don't know if I am missing something but Brad O states clearly in reply 271 (either page 16 or 17 ish) that the 6500 cannot measure volts and current together, maybe the answer is as simple as that? :-//
 

Offline Mike G

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #658 on: August 01, 2019, 04:48:31 am »
Sorry I meant page 11 or 12 ish  |O
 

Offline maxwell3e10

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #659 on: August 01, 2019, 05:10:28 am »
He said "MegaVolt is right, the DMM6500 can't measure Voltage and Current simultaneously" - which is right, none of DMMs can measure two things really simultaneously (one needs a simultaneous-sampling DAQ for that).

But it should be possible to measure voltage while current is still flowing through the terminals. In a setup where a DMM is used to measure current it is impractical to keep disconnecting the current for measuring voltage, and it  also changes the circuit because of burden voltage change.
 

Online Kleinstein

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #660 on: August 01, 2019, 05:31:04 am »
It looks like that with the current software, they can not measure voltage accurately with significant current flowing. This can't work using the same terminal: there would be at least some resistance in and between the plugs in the common terminal.  The error may be acceptable at low currents, e.g. in the mA range if the voltage is not that low (10 V range). The higher voltage ranges seem to have an additional problem with the DMM6500 from the odd connection of the divider.

In theory they should be able to add this feature with a modified software, if the sense terminal (likely Ohms sens low) is used for the "negative" side of the voltage reading, at least for low voltages 0.1 ..10 V ranges. The 100 V range won't work well with the divider directly to common terminal. To some degree the sense terminals could be seen as secondary inputs and they are used like this in the ratio mode.
 

Offline 2N3055

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #661 on: August 01, 2019, 06:06:39 am »
Did you short out (or put some resistor) across the voltage inputs of the meters? Otherwise, they do read zero but its not an accurate representation of what happens if some voltage source is connected.

No, I forgot to short them, hence why on low ranges they were collecting charge (GOhms). But they behaved exactly the same when nothing is connected (also to current input) so I assume it is fine. DMM6500 was also tested the same way and yet it showed 2.5V out of nowhere, on 10MOhm ranges that don't accumulate that much charge.

Rigol DM3068 also didn't measure anything without shorting voltage input. I guess when shorted, we measure internal voltage drop on that branch of ground caused by current flow...

It all means pretty much nothing. It is using meter outside intended use..
Fact that you can program it, doesn't mean you can do what hardware wasn't meant to do...
« Last Edit: August 01, 2019, 09:48:38 am by 2N3055 »
 
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Offline imo

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #662 on: August 01, 2019, 07:19:39 am »
What would be the typical "use cases" for such a setup (provided all work fine) with one common terminal? Normally, I would expect something like - to measure a voltage between the nodes A and B, and the current in any wire in my wiring. Thus I would need V+ V- and I+ and I- terminals, all floating.
« Last Edit: August 01, 2019, 07:22:00 am by imo »
 
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Offline KedasProbe

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #663 on: August 01, 2019, 10:45:47 am »
Rigol DM3068 also didn't measure anything without shorting voltage input. I guess when shorted, we measure internal voltage drop on that branch of ground caused by current flow...

It all means pretty much nothing. It is using meter outside intended use..
Fact that you can program it, doesn't mean you can do what hardware wasn't meant to do...
When you try second measurement on the DM3068 it shows a pop-up message on the screen that voltage measurement and current measurement can not be combined. Although I think they designed it with the possibility in mind and disabled it later.

It could be that a firmware update just disables the option for the DMM6500
« Last Edit: August 01, 2019, 10:47:28 am by KedasProbe »
Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 

Offline KedasProbe

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #664 on: August 03, 2019, 02:39:33 pm »
Hi,

Just to let you know that I updated the linear conversion script
https://github.com/Ken26M/keithley/blob/dev/Instrument_Examples/DMM6500/LinearConversion.tsp

I added a few defaults, including 1 to 1, I let you figure out why ;)

« Last Edit: August 03, 2019, 02:41:12 pm by KedasProbe »
Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 
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Online Kleinstein

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #665 on: August 03, 2019, 02:54:19 pm »
What would be the typical "use cases" for such a setup (provided all work fine) with one common terminal? Normally, I would expect something like - to measure a voltage between the nodes A and B, and the current in any wire in my wiring. Thus I would need V+ V- and I+ and I- terminals, all floating.

A possibel such case would be measuring the voltage / current relationship of something nonlinear (e.g. a incandescent lamp, input side of SMPS). The classical setup is to use 2 meters, one for current and the other for voltage. Doing both reading with the same meter, without disconnecting the wires and upsetting the current flow would be a nice plus. This meter could even combine the data and plot the curve.
 

Offline KedasProbe

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #666 on: August 03, 2019, 03:09:14 pm »
Basically high voltages >10V combined with low current <1mA won't really notice the 30┬ÁV voltage drop.
For other combinations you would need to take it into account that you have a variable offset or use two DMM.
(assuming the big error of the 100V/1000V range is fixed)
Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 

Online Kleinstein

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #667 on: August 03, 2019, 05:30:44 pm »
The higher error is likely from the way the divider is connected. So there likely is no fix to the higher error in the 100/1000 V ranges. So the less critical voltages would be more some 2-10V.

One may be able to correct some of the coupling, but chances are the internal resistance is copper wiring and maybe contact resistance (front to rear switch), so it would not be very stable. Still some correction (e.g. 95%) is better than the full error. 
 

Offline drummerdimitri

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #668 on: August 07, 2019, 08:25:14 pm »
Anyone else having major lag/freezing and crashing issues with their DMM6500?

It's so bad I'm having a hard time using the damn thing! I've upgraded to the latest firmware and this issue still persists  :-

How are you dealing with this major annoyance?
 

Offline KedasProbe

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #669 on: August 08, 2019, 05:03:25 pm »
I had a crash on my first day use but haven't had it since.
What I do though is I don't change the def1buffer size and don't use the apps. (I do use scripts)
I assume they have some memory problems with changing buffer sizes.
I use USB and network.
Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 

Offline KedasProbe

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #670 on: August 09, 2019, 01:34:40 pm »
Is it possible to load an lua module?
like:
complex = require "complex"
https://github.com/h4rm/luafft/blob/master/src/luafft.lua


Not everything that counts can be measured. Not everything that can be measured counts.
[W. Bruce Cameron]
 

Offline drummerdimitri

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #671 on: August 10, 2019, 10:14:33 pm »
This DMM is completely unusable and extremely frustrating!  |O

This can't possibly be right!

I've attached a short clip demonstrating how the instrument is totally unresponsive. I can't be the only one having these issues right?

https://mega.nz/#!MZURjIxQ!z3RixZ78lUd9IsXTKDPOkJ3QRNn7nYZNAlUjnb4h_-4

 

Online MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #672 on: August 10, 2019, 10:19:33 pm »
I've attached a short clip demonstrating how the instrument is totally unresponsive. I can't be the only one having these issues right?
It seems like a malfunction of the device.
 

Offline shodan@micron

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #673 on: August 10, 2019, 10:24:21 pm »
This DMM is completely unusable and extremely frustrating!
Seems like your DMM want repair.
I use 6500 about 1 year - all works fine, capacitive touch is very sensitive, and working on all my touches.
« Last Edit: August 10, 2019, 10:31:48 pm by shodan@micron »
 

Offline drummerdimitri

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #674 on: August 10, 2019, 10:31:31 pm »
This DMM is completely unusable and extremely frustrating!
Seems like your DMM want repair.
I use 6500 about 1 year - all works fine, captivate touch is very sensitive, and working on all my touches.

How can I tell if the touchscreen is the culprit or a bad firmware?
 


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