Agilent 3458A GPIB Data Aquisition software and options ?

[HighVoltage]

I finally bought an Agilent branded 3458A in hopefully good working condition and without the troublesome drift that some people have been talking about here on eevblog.
So far, the instrument has not arrived.

I will probably have this instrument calibrated by Keysight and then use it as a reference for my other DMMs and as a calibration bases for many 34401A, that I have in the field with customers.

Now I want to prepare for data acquisition with this DMM and compare it to my many other Keysight DMMs.
So, I looked around and found a few options.
I do have the original 82357B GPIB to USB adapter available.


BenchVue
Unfortunately, BenchVue does not support the 3458A


RF Scientific
This is a GPIB data logger software that was recommended to me by another 3458A user.
But, this software allegedly does not work with the original Agilent 82357B GPIB to USB adapter.
It requires the Prologix GPIB to USB adapter
http://prologix.biz/gpib-usb-controller.html
Can anyone here confirm, that this is true and that I can not use my Agilent adapter with the RF scientific software?

What other software options are there to collect data from the 3458A and also control the instrument remotely?
The RF Scientific software seems to be great, especially since it can be used to control multiple instruments at the same time.
It is just a bummer, that I can not use the Agilent adapter?

Any other ideas and recommendations?

[TiN]

How do u know if it's not drifty, if it was not received yet?

Also what's wrong with easiest linux-gpib + RPi way? Your hpak adapter should work just fine.
Sorry, site is temporary down so I can't bombard you with spamlinks yet.

Anyhow, welcome to no sleep no ppm club. That 3458 will suck up all your time now, be sure.

[carl_lab]

At the moment, I can't help you much, but did you try this?
http://rfscientific.eu/kontakt
The software looks nice,  and it is freeware.   

BTW: I have the same Agilent GPIB-USB adapter and want to log several 3458A over time to compare their drift.

...welcome to no sleep no ppm club. That 3458 will suck up all your time now, be sure.

No problem, if you can do all the testing at work... 

[HighVoltage]

How do u know if it's not drifty, if it was not received yet?

Also what's wrong with easiest linux-gpib + RPi way? Your hpak adapter should work just fine.
Sorry, site is temporary down so I can't bombard you with spamlinks yet.

Anyhow, welcome to no sleep no ppm club. That 3458 will suck up all your time now, be sure.

Well, what I meant to say was that it is "hopefully" not drifting. I heard that even newer models are drifting. So, fingers crossed until I am testing it.

Yes, I searched google and your website came up a lot, just a dead end right now.
There is a saying: "If you want to get something done, ask a busy person"
I am very busy with so much stuff but I am also looking forward, playing with this meter.
Hopefully this will solve my "two watches" problem.

When will your website be up again?

[HighVoltage]

At the moment, I can't help you much, but did you try this?
http://rfscientific.eu/kontakt
The software looks nice,  and it is freeware.   

I have the same Agilent GPIB-USB adapter and want to log several 3458A over time to compare their drift.

...welcome to no sleep no ppm club. That 3458 will suck up all your time now, be sure.

No problem, if you can do all the testing at work... 

You have more than one 3458A at work?

Email was sent to their support site, may be the answer is positive.
But since the driver for the Agilent 82357B GPIB to USB adapter is installed with the I/O library, I would expect this adapter to also be working easily.

[carl_lab]

You have more than one 3458A at work?

Yes. 
And they all seem to behave different... 

[joeqsmith]

Did you get one with the oven?  These are nice.

Because anytime I have need to use one of these, these tests are always custom. I roll the code in Labview using  the newer version of National Instruments Ethernet GPIB controller.   

[HighVoltage]

Did you get one with the oven?  These are nice.

Don't they all have an oven?
I think, - but I am not sure- , that the higher stability option 2 has only a differently set oven temperature?
But the LTZ1000 is heated in all of them, as far as I have read so far.

[G0HZU]

What other software options are there to collect data from the 3458A and also control the instrument remotely?

The easiest/best way is to create something in excel to log over GPIB or write a few lines of code in VB to do it.  Or use Python or something similar.

It looks to me like that RFScientific logger program just date stamps and logs each DMM reading and sticks the result in a spreadsheet every few seconds? Maybe it can log faster than this but that program looks like some kind of slow and boring DMM comparison/crosschecking program for people who have far too many bench DMMS and nothing better to do than log them against each other for hours/days at a time.

[carl_lab]

Did you get one with the oven?  These are nice.

Don't they all have an oven?
I think, - but I am not sure- , that the higher stability option 2 has only a differently set oven temperature?
But the LTZ1000 is heated in all of them, as far as I have read so far.

That's correct, option 002 has reduced temperature setting for lower long term drift.
(PS: I'm not sure about it anymore, maybe I was wrong...)

I think here are some specialists, who made a modification (changing a resistor) on their "normal" 3458A's to have the same effect.
I'd like to know, if this modification is as good as the manufacturers option 002 (maybe manufaturer also uses harder selected LTZ1000)...

[joeqsmith]

Did you get one with the oven?  These are nice.

Don't they all have an oven?
I think, - but I am not sure- , that the higher stability option 2 has only a differently set oven temperature?
But the LTZ1000 is heated in all of them, as far as I have read so far.

I have never had one apart or looked for a service manual.  I was guessing the high stability was a double ovenized setup but really don't know. 

[acbern]

The lower drift version opt 002 is just selected parts, no change in temperature. An old, well aged 3458A will have the same or better bahaviour by today. You just cannot claim it is low drift, unless you qualify that yourself. And opt 002 only improves DCV. You can get even better accurcy using a standard 3458A and doing relative measurements to a voltage reference such as the 732. Thats what I do anyway if I need to do precision measurements (better 2ppm abs).

[edpalmer42]

Some other software options are:

NI Labview Home ($50)

or

EZGPIB (free).  It's a Pascal-based interpreter with GPIB extensions.  One of the example programs is for an HP 3457.

I've also heard of PyVisa and pylt, but I don't know anything about them.

Ed

[TiN]

The lower drift version opt 002 is just selected parts, no change in temperature. An old, well aged 3458A will have the same or better bahaviour by today.

acbern is right on money. All three reference modules are different just thru selection. Selected best ones go into HFL (2ppm/y, ~1.7K$ from HPAK site for A9 reference module), second best are Opt.002 (4ppm/y, ~1k$) and standard are for rest (8ppm/y). They all running scorching hot 90-ish C via 15K/1K temperature setpoint resistors. I'm not aware of any other difference on A9 reference between the three, except the selection of LTZ1000A's. There is also important to watch out for ones with pink noise shots (random jumps in voltage, usually 0.3-1.5ppm scale). These can be detected by monitoring known clean and stable LTZ module or similar 10V reference.

I added 100K in parallel with 15K long ago , to bring temps down ~50c, as my max room temperature is around +35c tops. Lower temperature allow to reduce aging rate, which I decided worthy, since my meter is running 24/7 non-stop since repair was complete.

Beware that you will lose calibration after the mod, as reference output voltage shifts a lot.

EZGPIB (free).  It's a Pascal-based interpreter with GPIB extensions.

Yup, I used that one for DMM noise testing project we had while ago. I have program to run on 3458A for it as well.

Server will be back tonight, once I come back Taiwan from business trip and check on it. Murphy law gotchas, everything runs months once I'm home, and breaks second day I leave the country. 

[carl_lab]

The lower drift version opt 002 is just selected parts, no change in temperature. An old, well aged 3458A will have the same or better bahaviour by today.

acbern is right on money. All three reference modules are different just thru selection. Selected best ones go into HFL (2ppm/y, ~1.7K$ from HPAK site for A9 reference module), second best are Opt.002 (4ppm/y, ~1k$) and standard are for rest (8ppm/y). They all running scorching hot 90-ish C via 15K/1K temperature setpoint resistors. I'm not aware of any other difference on A9 reference between the three, except the selection of LTZ1000A's. There is also important to watch out for ones with pink noise shots (random jumps in voltage, usually 0.3-1.5ppm scale). These can be detected by monitoring known clean and stable LTZ module or similar 10V reference.

OK, then I have mixed up your modification with option 002, I'm very sorry!

I added 100K in parallel with 15K long ago , to bring temps down ~50c, as my max room temperature is around +35c tops. Lower temperature allow to reduce aging rate, which I decided worthy, since my meter is running 24/7 non-stop since repair was complete.
Beware that you will lose calibration after the mod, as reference output voltage shifts a lot.

The resistor you used additional, need to be special high stability type?
If you modify temperature setting, will a selfmade artifact calibration be enough to correct?
Or is a full factory calibration/adjustment needed?

Sorry for OT, but I could not find the original modification thread using the forum's search function.
So if moderators want to move modification posting(s) to modification thread, please give me the link to it...

[acbern]

When you change the resistor defining the temperature of the LTZ, a new artifact adjustment is necessary. This is anyhow the only way to adjust the meter (except for regular ACAL, which is important; it should be done more than just once a day when meter is in use, just to be sure). Now you have the issue that you formally should do a performance verification. This will confirm everything went right during artifact cal. There is a military paper saying performance verification after artifact cal is needed only every second time (to comply to certain mil requirements; forgot the link, but google will certainly find it). However, this will not be acceptable according to dakks and  probably not to any other national cal organization requirements.
For a home lab, different story. But if you go that route, you can as well do artifact call every month or so and have a very low drift instrument without mod.

[HighVoltage]

acbern,

This is very interesting about the different models:
So, let me summarize:

- Normal version: 8ppm/y
- Option 002: 4ppm/y
- HFL: 2 ppm/y (Was only sold by Fluke, right)

And all three versions are running with the high temperature in the LTZ1000?
And the only difference is for Keysight to select the lowest drift reference for the best HFL meters, after they have aged them for a long time in the factory, may be many month or years?

What about all these 3458A reference boards showing up on ebay?
Are those mainly rejected boards or how is it possible that so many of them are on the market?
Or is it possible to find a 2ppm version under those?

[Dr. Frank]

HighVoltage, congratulation to your 3458A!

The LTZ reference modification, 100k in parallel to the 15k, requires a low T.C. resistor, 3ppm/°C is sufficient.
This brings the oven temperature to about 65°C, like in the LT datasheet, which should be good for <2ppm/ year.

As the initial stability should have been < 8ppm/year, by HP specification, and the temperature reduction is about 30°C, even a factor of 8 better stability may be expected.
All these numbers are valid for continuous operation, 24/365.
If the instrument is switched off, there will be practically no drift.
Hysteresis might happen with the original references, see AN-18, which is also less probable at lower oven temperatures.


You have to take care that the interior does not heat up in total (TEMP?) to more than about 50°C.
This limits the maximum room temperature to < 35°C, the fan has always to be kept clean, and the instrument should not be stored in a closed rack.
In other words, this modification is for lab / metrology environment only.

It's not really known, what modifications were done in the Fluke HFL3458A version.
Maybe Fluke used their own voltage references, based on the LTFLU.


Frank

[acbern]

highvoltage,

most old and still good voltage reference by today, especially when operated at lower temp with parallel resistor mod, will most likely be equivalent in drift to the opt. 002. reason being, keysight selects them new and extrapolates drift. and references drift more when new.
those on ebay are a gamble, because their origin is unknown. never bought one.

in your case, what I would do, is to validate your instrument as-is (potentiall with the mod, but no upgrade to opt 002). you would need a stable, calibrated voltage reference (732/4910), or access to it to calibrate the unit and check the drift. According to PTB, if you do that three times, and have a drift history, you can use this as the drift rate going forward. Unless you bought a bad unit, I am sure you will be 002-equivalent in drift rate, especially if you do the mod. you need to establish this, as you use it for your customers, so you need some evidence.

or, if you want to spend the almost 1k (for a opt002 upgrade), i would rather invest this in a 732 or so.

[HighVoltage]

Dr.Frank
Thanks for these great explanations.

As you know, I have this external LTZ1000 reference that you qualified for me once.
Can I use this reference to analyze the drift of my 3458A, once I have it?
Or is there a better way, since I don't have a 732?

May be someone that has a HFL3458A at work, can do a teardown and find out if there really is a LTFLU reference installed, as is in the DMM7510 from Keithley.

acbern
This means that eventually all 3458A meters will end up to be equivalent to a new one with option 002.
Does this also mean, that those units with option 002 will eventually be like an HFL3458A
If so, the $1k investment in to an option 002 upgrade would be wasted and as you said, much better invested in to a stable 732.
But then I have the problem of finding a stable 732.

Thanks for all the good hints.




 

[acbern]

I cannot comment about the HFL as I am not aware about the details internally. But generally, finding a LTZ itself, that drifts 2ppm per year, is achievable. Now there are other parts within the 3458A that drift and cannot be compensated by an ACAL DCV. Therefore, HFL stability may be a stretch.
Anyway, going with a 732 is the better aproach, because validation is doable any time. When I do precision mesurements based on comparison to a voltage standard, so I dont care about the drifts of my 3458As. That way I can get around 2ppm abs. any time a year on 10V and 1V. Finding e.g. a good 732 is a challange though, trial and error to a certain extent. When I finally got mine, it was my third.

[TiN]

I don't think HFL DC reference was anything but preselected LTZ1000 A9. Why I think so?
Because HPAK site have part "03458-66529, PC Assembly-DC REF Tested 2 PPM,Orderable,   US$ 1931.00".
So if someone want 2ppm selected reference and has extra 2K - here they are

HighVoltage I'm back home, and site is up. I had messed up SSL-key on my nginx config 

[Dr. Frank]

Dr.Frank
Thanks for these great explanations.

As you know, I have this external LTZ1000 reference that you qualified for me once.
Can I use this reference to analyze the drift of my 3458A, once I have it?
Or is there a better way, since I don't have a 732?

Thanks for all the good hints.

HighVoltage,
By means of an external LTZ1000 reference, you will be able to check for the short -term drift of the 3458A, like described in AN-18, or like checking A3, what TiN has done.

A >24h datalog of the external reference with one initial ACAL, but none meanwhile, will reveal any excessive drift of U180.

A single external LTZ will not identify long-term drift rate, as you would be the man -with-two-clocks only.
A third reference, preferably a SZA263 based, would be necessary to decide, and probably would allow to measure the 3458As drift, if it would run continuously.

Frank

[TiN]

What about all these 3458A reference boards showing up on ebay?

A9 I bought from eBay (STD option) had ~1.2ppm pink noise and random jumps. After replacement of LTZ chip - that was solved.
Interesting enough - "bad" noisy chip was later checked on my KX reference board and it had no jumps. However direct comparison is not possible, as it was running different zener current and also had 400K compensation resistor, just like LTZ1000CH reference design, instead of no resistor for ACH chip (which is from 3458A's A9 board).

If you can't find datalogs in my repair log, I can post them here later.

For the setpoint mod I used wirewound card resistor, ~3ppm/K.

P.s. GPIB article for 3458A.

[Alex Nikitin]

Now I want to prepare for data acquisition with this DMM and compare it to my many other Keysight DMMs.
So, I looked around and found a few options.
I do have the original 82357B GPIB to USB adapter available.
...

Any other ideas and recommendations?

I'm using EZGPIB and the program from TiN's site for our HP3458A with the original 82357B GPIB to USB adapter. It allows you to set the measurement parameters and log the data. Works fine and sufficient for my needs at the moment.

Cheers

Alex