34465A - 34461A Digitizing / Data Logging - Page 1
Forum section: electronics / testgear

author: mtnzap73
author_rank: Contributor
timestamp: October 08, 2020, 06:14:29 pm
content: I do not own either of these DMMs. I am researching the specs and this forum. Keysight specs indicate that for digitizing / data logging, the main difference with the 34465A is that it captures data on the unit.Also, it is indicated that digitizing / data logging can be done on the 34461A via BenchVue.Currently the 34465A comes with the DIG option. So, the following statement may be moot: taken fromhttp://rfmw.em.keysight.com/bihelpfiles/BenchVue/BV_2018_HTML5/DMMApp/English/Default.htm#Digitizer%20Mode.htm%3FTocPath%3D_____7* BenchVue supports digitizing on the 34465A and 34470A DMMs without the Digitizing Option (Option DIG) installed in the DMM. Note, however, that an internal trigger source and pre-trigger count are not supported in BenchVue without the Option DIG installed in the DMM. This license is separate from the BenchVue license and both licenses must be installed to use the full set of digitizing features in BenchVue.>> What is the implication of this statement for 34461A digitizing / data logging via BenchVue?>> Bottom line: for digitizing / data logging, is there an advantage with the 34465A, *other than its local storage capability*? (I can see the other obvious spec differences)

author: HKJ
author_rank: Super Contributor
timestamp: October 08, 2020, 06:40:31 pm
content: For digitizing I would take DMM6500 any day over the Keysight ones.For logging at more moderate speed you do not need BenchVue, there are other (free) software.

author: SilverSolder
author_rank: Super Contributor
timestamp: October 08, 2020, 06:43:53 pm
content: I guess it depends on whether you need the triggering function, or if you are OK with letting the logging run like a chart recorder and cut the parts out that you want later?

author: Dr. Frank
author_rank: Super Contributor
timestamp: October 08, 2020, 07:45:11 pm
content: Quote from: mtnzap73 on October 08, 2020, 06:14:29 pmNope, that's not correct. The 34460/61 can only do 'Data Log', but NO 'digitizing', also not via BenchView.The sampling time AND the data rate of the 34461 are limited to NPLC 0.02 and 1000 samples /sec, either direct, to memory, or over the bus. That's done @ 4 1/2 digit.You need to study the manual also, page 452 + 455, Resolution and Integration Time for DC Measurements.The term 'Digitizing' is used for faster rates down to 20µs/50kHz.The 34465A should also have the memory option to make optimal use of its 50kHz @ 4 1/2 digit digitizing. BenchView is a bit clumsy, and does not fully support real time digitizing at full data rate with high number of samples. That also depends on the interface used, GPIB limits the speed even more, compared to LAN or USB.The 34465A has other useful advantages, like level triggering, digitzing of DC current (DCI), and - you did not ask that - the low current ranges.So it depends on your needs for speed.Frank

author: mtnzap73
author_rank: Contributor
timestamp: October 08, 2020, 10:07:40 pm
content: Dr. Frank's reply is exactly why I asked the question. I suspected as much.Just for fun, take a look at this link:http://rfmw.em.keysight.com/bihelpfiles/BenchVue/BV_2018_HTML5/DMMApp/English/Default.htm#Digitizer%20Mode.htm%3FTocPath%3D_____7I guess the second line, "Digitizer mode is available for the 34410A, 34411A, 34460A, 34461A, ..." is simply incorrect.Thanks also for those other benefits of the 34465A; I didn't ask, but you could tell it would be my next question.Thanks HKJ also for the DMM6500 reco.

author: mtnzap73
author_rank: Contributor
timestamp: October 09, 2020, 12:49:31 am
content: Per suggestion, I looked into DMM6500.Folks will need to give me some grace for my question below:The manual and any docs I can find are not for basic operation. The manual is pretty focused on using a scan card, a cool extra $1K.I believe I can work out that one can use an RTD for temperature measurement from the SENSE terms on the front panel.So, is there any documentation for the DMM6500 that is at the very basic level? Functional walk-thrus?Even coming from an engineering background, I always learn something from the most basic of manuals. It confirms those airy feature lists.Unless I am missing something, I cannot see such documentation for the 6500.Can anyone point me to some docs?

author: Electro Fan
author_rank: Super Contributor
timestamp: October 09, 2020, 01:41:41 am
content: https://download.tek.com/manual/EN-DMM6500-900-01_Users_Manual_DMM6500-900-01A.pdf

author: mtnzap73
author_rank: Contributor
timestamp: October 09, 2020, 02:35:29 am
content: Thanks Electro Fan.I actually have the later version of that manual, and here is a question:It details how to take temperature measurements using the 2001-scan card, which itself uses K thermocouples.But I don't have the scan card.The manual does not detail how to take temperature measurements without the scan card.It does indicate how to do 4-wire measurements, and that can be a RTD. Nothing about thermocouples.Unless I am missing something.I realize one can argue that the standard DMM terminals are present, and if one knows how to use a standard DMM of any brand, then it does not need to be explained in DMM6500 docs. I beg to differ.In comparison the Keysight 34461A/34465A manual describes thermocouple, RTD measurements in excellent detail.

author: mtnzap73
author_rank: Contributor
timestamp: October 09, 2020, 03:09:41 am
content: DMM6500 Reference Manual is what I am looking for.1257 pages; pure bliss!Ignore my stuff above please ....

author: Electro Fan
author_rank: Super Contributor
timestamp: October 09, 2020, 03:10:00 am
content: Seems to be a digitizer use case but maybe be someone here that can help with 6500 temp questions:https://www.eevblog.com/forum/metrology/calibration-of-prts/msg3239880/#msg3239880And many of the 6500 users here:https://www.eevblog.com/forum/testgear/new-keithley-dmm6500/

author: mtnzap73
author_rank: Contributor
timestamp: October 09, 2020, 05:04:41 am
content: Thanks again.I actually did find the reference manual. The Tek site was down which didn't help.

author: Kleinstein
author_rank: Super Contributor
timestamp: October 09, 2020, 09:45:35 am
content: For thermocouple measurements one needs cold junction compensation of some kind. AFAIK the 6500 and 3446x don't include this in the base meter. The scan card may also include an extra sensor for cold junction compensation or one can at least add one (use 1 channel for this).The Keitley 6500 is different from the Keysight meters in that it uses a separate ADC for the digitizing / very fast conversions. So the specs are quite different for the slow and fast range. The 3446x use the same ADC, just shorter integration. So the digitizing mode is the same as fast data logging. The resolution also goes down the high speed.For the K6500 also keep in mind that it has a high sampling rate, but the bandwidth of the amplifier front-end is limited. So the input waveform gets distorted in the time domain.

author: HKJ
author_rank: Super Contributor
timestamp: October 09, 2020, 10:50:55 am
content: Another advantage when "digitizing" on the DMM6500 is the display, it is much better. This waveform display can be used with both the normal ADC and with the fast digitizing ADC.I have 34465A, 34470A, DMM6500 and DMM7510 on my bench. For most measurement I can use any of the meters, but for digitizing I always uses the DMM6500 (The DMM7510 gets seldom used due to fan noise). The reason I have that many meters is because I often use them for logging data.