Agisight 3446/7XA Digitize option - Page 1
Forum section: electronics / testgear

author: dadler
author_rank: Unknown
timestamp: August 06, 2015, 10:57:04 pm
content: Does anyone out there have this option, and if so can you provide any feedback on its performance?- Have you found specific situations where this option was truly useful?- Do you think it was worth the cost/would you buy it again in retrospect?- Is this option very useful even if you do not also have the extended memory option, or do you really need the extended memory to get real value out of the digitize option?- Any other opinions or insights.I am considering purchasing the option for my 34465A.Thanks in advance.Dustin

author: Lizerd
author_rank: Contributor
timestamp: August 07, 2015, 07:42:45 am
content: I have the 34411A at work, and I bought it just because of the 50KHz sampling rate capability.Used it for recording current consumption in high-speed to be able to calculate and optimize the total consumption of a device.So it depends on what you are going to use it for.I am also going to buy the 34465A with the DIGI option for my self.So if you buy the DIGI option, please write some comments about your though after you test it out.I know that the 34411A do not have the best way to control the high-speed capture, only a bad web interface.So I had to write a .NET program that controls the logging options and data extraction and plot.But the data from the instrument is really good.

author: Dr. Frank
author_rank: Super Contributor
timestamp: August 07, 2015, 09:01:54 am
content: Yep, I got a 34465A with the DIGU option. (Thanks to HighVoltage)It already helped me, because it is doing DCV and also DCI digitizing at 50kHz rate, even in the low current ranges, down to 1µA. (see at the bottom of this article)This is quite unique, as neither the 3458A can do this (2kS/s limit), nor the 34411A, afaik.Disadvantages are:- limited memory depth (50kS), the 2MS option is expensive.- limited bandwidth (15kHz, I assume from the 34411A spec.)- no Ohm digitizing, as 34411 and 3458 provide.Keysight claims compatibility to the 34411A (don't own this unit), but I already found some differences, if using the fast digitizing features under GPIB control:In normal acquiring mode for DCV and DCI, it is not possible to use the full 50kHz speed, i.e Disp off, 20µs, etc.One parameter cannot be set to zero, I think that's the delay, and that prevents full speed.Additionally, the FORMAT parameter only allows 64bit real output, instead of 32bit as with the 3441A, which reduces the data rate over the output interfaces too much..For both reasons, it's not possible to really do fast digitizing at 50kHz, 16Bit, directly to the PC, and with unlimited data depth.I assume (but did not see a code for that), that it wold be possible with the 34411A.Keysight maybe want to protect their MEM option, or the whole state machine is too slow..I will also complain about that soon in face to Keysight..(The 3458A anyhow, can do real fast 100kHz digitizing in DCV, Ohm, at 150kHz bandwidth, and better)Now about the DCI digitizing..I have built a precision current source, 100mA ... 100nA, < 0.005%, which is very stable in the upper ranges, and can be trimmed stably to ppm level also, by means of my 3458A.Nether the less, the low ranges 10µ and 1µA were a bit flickery on my 3458A, anyhow precise to 10ppm, or so, if using longer sampling intervals. I already shielded sensitive parts of the circuitry.When I now got my new 34465A, it displayed overload in the 1µA range, measuring 1µA or 100nA output from the current source.So I digitized the signal on the 10µA range, et voilà, there was a 3µA, 50Hz ripple on the 1µA DC signal.I made a freshmans fault when later adding a huge resistor decade divider inside the box, unshielded, of course, which picks up the field from the nearby mains transformer... and all the time I was wondering about this problem...By feeding the box externally with a lab PSU, the ripple of course vanished, and now the DC source is practically noise free, and the 3458A also delivers much more stable readings.. ready to improve it to 0.001% stability / accuracy.I wouldn't have found that error w/o the easy to use DCI digitizing and display features of the 34465A!Ok, here's another comfortable DCV digitizing application.I measured the output stability of a high voltage 100:1 Hammon type precision divider, either measuring directly its 10V output, (the 34465A resolves 7..8 digits!), or in difference mode against a stable 10V reference, on the 1V range of the 34465A (recovery behaviour after 10V overload??).Purpose was to measure the thermal drift (under a 1000V load) with high resolution, 200µs .. 500µs over several minutes, to detect self-heating effects of the individual divider resistors.So the 50kS limit was acceptable.It was really nice to have the direct display of the drift on the trend diplay in real time, but also to analyse it later via csv file in xls.It turns out, that the drift is low as expected, so this Hammon type divider really is capable to divide these 1000V stably to around 1ppm initially, but I have to further analyse, what's the root cause of the longer term drift, see diagrams (HV is applied at exactly 2.575 sec).Well, I also could have used the 3458A for that measurement, but I would have needed to write an elaborate program.. 100% more comfort with the 34465A, and the proof, that you don't need an 8 1/2 digit DMM for such delicate / sensitive measurementsAnd yes, I would buy this option again, although I got this option for less, (as I got the whole instrument) and before the recent 15% price increase here in EU.Frank

author: HighVoltage
author_rank: Super Contributor
timestamp: August 07, 2015, 03:24:05 pm
content: I do have this option in my 34470A and it does provide exactly what I needed for some signal analysis. Right now I am traveling but when I am back, I will post some great screen shots and results that I got out of the DIGI option. And yes, I would buy it again.

author: dadler
author_rank: Unknown
timestamp: August 07, 2015, 06:33:59 pm
content: Thanks for the responses.I am getting a little irked with Keysight licensing in general.I ordered a bandwidth upgrade license for my DSOX3000T a week ago, and my order seems to have disappeared into the ether.Newark are claiming that Keysight has not honored the request and it has been "expedited" twice. Newark isn't a bunch of angels but I have had generally good experiences in the past--so I tend to believe them when I am told Keysight is dragging their feet.I was going to order the DIGI option to do higher-fidelity voltage datalogging that I can't get with my scopes. I am trying to diagnose and fix an ongoing problem with an automotive fuel pump controller and I think the right tool for the job is something like the DIG option--although I probably need the memory option too for this use case.

author: dadler
author_rank: Unknown
timestamp: August 11, 2015, 11:42:11 pm
content: Had these two options in my cart and almost pulled the trigger.. but after all the hoop-jumping to get the license for my scope (still waiting), I just don't want any more headache.You'd think they'd make it easier to give them money for options, especially since they are pure profit?

author: Sparky
author_rank: Frequent Contributor
timestamp: December 28, 2015, 09:11:57 am
content: Quote from: HighVoltage on August 07, 2015, 03:24:05 pmWould still love to see whatHighVoltagehas been doing with the DIG option! Not many people here seem to have the DIG option, and fewer have shown any results of what it does for them. I think it's a really valuable tool for analyzing power draw, especially in battery powered embedded systems. I just posted some results in the mainAgilent 34465A/34470A thread. This thread could have become a trove of useful information if it weren't for the obscure title --- "Agisight 3446/7XA Digitize option" isn't a good choice. There's excellent information contributed here by Dr. Frank, and probably many more people would have replied but the thread title is such an obscure mashing/truncation/abbreviation of company and product names that very few people will ever end up here...why do people do that?