Picotest M3510A vs HP/Agilent 34401A - Page 1
Forum section: electronics / testgear

author: supercilious
author_rank: Contributor
timestamp: February 23, 2016, 12:03:19 am
content: Hi,Total newbie here, looking to buy my first bench meter and the various normal beginner 5.5 digit options (Rigol, Siglent) seem to have issues with PC connectivity which is a must for me... I don't care much about the physical interface as I will be mainly using it via the PC, and the higher end meters graphing and histogram stuff is completely wasted on me, I have a nice set of large monitors I would rather look at than squint at a tiny LCD.What is your opinion on the relative merits of the Picotest M3510A vs HP/Agilent 34401A? The M3510A is around £250 (ebay) while the HP/Agilent is around £320 (local distributor, used), which is ideal since it means I can afford to get two of them!Basically, aside from maximum precision and accuracy the main thing I care about is the PC connectivity. Both of these meters are well supported in that regard and can be used with lots of different software and the protocol is simple enough that custom code can easily be written to do unusual things should the need arise. Everything else is "nice to have" but strictly superfluous. The Picotest has dual measurements which is very nice and in particular the ability to measure current and voltage at the same time, but aside from that, nothing really stands out.Does it matter that the Picotest switches ranges at unusual voltages compared to most other 6.5 digit meters? (1m count vs 2.4m count??)Which should I go for? Perhaps something else entirely that I've overlooked?Thanks

author: TheSteve
author_rank: Unknown
timestamp: February 23, 2016, 12:57:46 am
content: The 34401A can be serviced/calibrated by any number of people/places globally. It is also time tested and well proven. It will also likely hold its value for years to come even though the design is 20 years old.The M3510A I have no experience with.I'd choose the Agilent over the unknown everyday.

author: supercilious
author_rank: Contributor
timestamp: February 23, 2016, 01:10:52 am
content: Quote from: TheSteve on February 23, 2016, 12:57:46 amYeah, that was my instinct too. I am definitely erring towards the Agilent, even though I am not likely ever to sell it.However, the Picotest is actually a rebadged Keithley, somewhere between the Keithley 2100 and the Keithley 2110, so I don't think there would be much trouble finding someone to service/cal it.

author: TheSteve
author_rank: Unknown
timestamp: February 23, 2016, 02:40:58 am
content: Keep in mind it is not actually made by Keithley - they just rebrand it.https://www.eevblog.com/forum/reviews/picotest-m3510a/

author: Helix70
author_rank: Unknown
timestamp: February 23, 2016, 02:44:01 am
content: We have a Picotest M3510A. Wish we have purchased the 34401A (or the 34461A) in the first place. The Picotest has been repaired under warranty twice, and I expect that the third time will relegate it to the rubbish bin.Buy cheap, buy twice.

author: tautech
author_rank: Super Contributor
timestamp: February 23, 2016, 08:54:20 am
content: Quote from: supercilious on February 23, 2016, 12:03:19 amFirstly, no problems here with SDM3055 to PC connectivity or reading the display from yards away.Bright yellow digits on a blue/grey background, very visible even in bright light.Haven't had mine connected to the PC for ages but it still works fine.Most PC connection problems stem from improper software installs, the NVISA SW must be installed first, them the instrument control SW and finally instrument connection. Failure to follow this order will result in Windows installing the incorrect drivers then connection fails and it's a nightmare to sort out.

author: supercilious
author_rank: Contributor
timestamp: February 23, 2016, 12:26:53 pm
content: Thanks guys for your input. It seems the consensus is that the 34401 is the meter for me, at least out of those two.As for the Siglent, I can't find a source ATM, but I do recall reading a review that mentioned problems with the PC connectivity. Does it have full software and protocol compatibility with the 34401? Anyone had issues with it? Aside from being 5.5 digits, is there a downside to the 3055 compared to a 34401? Bear in mind that it will be driven almost exclusively from the PC.

author: Performa01
author_rank: Super Contributor
timestamp: February 23, 2016, 12:44:39 pm
content: Quote from: supercilious on February 23, 2016, 12:26:53 pmThat's right, but these two meters aren't comparable from the beginning. The Picotest equivalent to a 34401A would be the M3500A - and out of these, I would chose the latter, not only because of its better short-term stability / lower noise, but mainly because it has USB and comes with nice plug-ins for MS Word and Excel, which allow very easy data logging without any additional effort, see example attached.

author: supercilious
author_rank: Contributor
timestamp: February 23, 2016, 05:58:51 pm
content: Its true that these meters are targeting slightly different market segments, but I was comparing them mainly on the basis of price.I have also since come across some other meters that will fit my budget like the Keithley 2015 THD and the Rigol DM3064. The Keithley seems quite appealing, but has some severe limitations in its current measurement abilities, lacking most of the ranges that other meters have. The Rigol meanwhile, I can find next to no information about it. Almost all reviews and documentation reference the DM3068, but I have no idea in what ways it differs from the DM3064, and the specs seem identical.Still not confident enough to pull the trigger on this purchase, but at the moment I am leaning towards getting the tried and tested 34401As.

author: Performa01
author_rank: Super Contributor
timestamp: February 24, 2016, 10:09:23 am
content: The basic functionality of the Keithley 2015 THD is identical to a Keithley 2000, which in turn is very similar to the 34401. All these meters (Picotest M3500A, Keithley 2000/2015 THD, HP/Agilent/Keysight 34401) have limited current ranges; particularly the lowest range is 10mA. There really is no difference.Connectivity is another factor. 34401 has only GPIB, Keithley 2015 THD has RS232 at least and only the Picotest is modern enough to provide USB.The Rigol DM3068 has slightly lower accuracy - in fact, it's almost the same! - as the ones mentioned above, but has some nice features, like complete current ranges, 2.2 million counts and high input impedance up to 22V. Even though it's fairly modern with LCD graphic display, functionality is not so great compared to the others in my book. I also think I've heard complaints that remote control doesn't work reliably, particularly HP 34401 emulation mode might be problematic, so you would have to investigate this before making a decision.Rigol DM3064 is an outdated instrument with inferior specs and even though I have no first hand experience, from all information I've come across it doesn't seem to be the meter I'd want.

author: KJDS
author_rank: Super Contributor
timestamp: February 24, 2016, 10:54:23 am
content: I've a pile of Solartron 7150plus with GPIB available at a very reasonable price.It's theoretically a 6.5 digit meter but the update rate in 6.5 digit mode is about 7 seconds, but it's fine as a 5.5 digit meter.

author: supercilious
author_rank: Contributor
timestamp: February 24, 2016, 12:04:19 pm
content: I just got my first 34401 for £280 delivered. Its Agilent branded with 2013-2014 calibration, so it can't be too far out of spec yet. Should have it in my hands in a few days. Still looking for my second meter. Managed to negotiate the price on the Picotest down to £200 with 1 year warranty... very tempting.The Solartron 7150plus looks dubious. Aside from its age and very slow acquisition rate, it has a poor history of reliability from what I can tell. The third google result is an exploded one

author: Performa01
author_rank: Super Contributor
timestamp: February 24, 2016, 12:14:56 pm
content: As it has been mentioned...the Schlumberger-Solartron 7150(plus) is a nice compact meter with GPIB, but its accuracy (80ppm) and short-term stability really are just that of a 5.5 digit meter. The 6.5 digit mode is just a moving average filter for resolution enhancement. The current range is even more restricted (as with most meters of that age) and it only provides a single 2A range. Even though it supports 4-wire measurement, the lowest resistance range is 2k. It has high input impedance only up to 2.2V. On the positive side, it has 230k counts (2.3 million in 6.5 digit mode) and AC accuracy is almost as good as any modern 6.5 digit meter, which was outstanding back in its time.No worries regarding reliability!There has been a batch of units where the mains input filter blew up eventually, but that is not specific to the 7150 and as far as I can tell, the meters survived. I have 4 such meters, still use them occasionally and none has ever failed, despite their age.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: February 24, 2016, 05:09:11 pm
content: Quote from: Performa01 on February 24, 2016, 12:14:56 pmThat input filter, if it is the one I am thinking of, has failed on a WIDE range of instruments.

author: Andy Watson
author_rank: Super Contributor
timestamp: February 24, 2016, 05:58:31 pm
content: Quote from: PedroDaGr8 on February 24, 2016, 05:09:11 pmYes, they're infamous. Shaffner smoke generators! I have two 7150s and the input filter has failed on both of them. Replacements are available.

author: supercilious
author_rank: Contributor
timestamp: March 01, 2016, 08:51:30 am
content: I've finally got both meters in my handsHaving played with both meters for a day or so, I can finally compare Picotest and Agilent for myself.I was originally going to get another Agilent, but the price of the Picotest was too tempting, so I got one of those insteadLuckily neither is out of spec; At least according to my cheap references they both agree on the readings.Anyone interested in a comparison?

author: Performa01
author_rank: Super Contributor
timestamp: March 01, 2016, 11:40:21 am
content: I would be interested indeed!... even though it's clear right from the start that the M3510 cannot be compared to the 34401 in terms of accuracy. In that regard it is really just like a mediocre 5.5 digit meter, but maybe its features are more valuable for someone who doesn't really need the accuracy.So I'd really like to hear (read) how you like it in comparison.

author: supercilious
author_rank: Contributor
timestamp: March 01, 2016, 12:37:41 pm
content: Firstly, I think it was a good choice to have two different meters, because they both have different strengths and weaknesses. Since I have only had the meters since yesterday, this is very much first impressions, so reader beware.Build:The Agilent is of course higher quality in terms of physical build, the buttons are nicer and the meter itself is overall heavier and more solid feeling than the picotest, which feels lighter than I expected, and the controls aren't as clicky and have less tactile response. As I stated in my earlier post, both of these meters will be driven by a PC 99% of the time so the feel of the device is of little importance to me. The screen on both meters are pretty bad in terms of readability, and the Agilent particularly sucks in a brightly lit room, while the Picotest LCD is a bit naff looking, it is at least quite readable under bright lighting conditions.Remote:I have yet to get the GPIB->USB stuff working for the Agilent (likely due to my crappy eBay adapter), but the Picotest was a breeze to connect up to the PC, and natively speaks the USBTMC protocols and VISA drivers work flawlessly. I tried to control with with a simple Python script with SCPI, and it worked straight awayI will write more about remote operation when I have the Agilent hooked up too.Front panel measurements:Here at the full 6 1/2 digits of both meters, the Agilent is significantly slower both at updating its readings and at ranging up and down. The Picotest is rather quick, and I had to increase the PLC count to be able to see the last digits clearly since they were changing too fast. For quick voltage measurements, the Picotest the better meter. However, the picotest has a rather loud relay that clicks when changing from the 1V range to the 10V range which can be annoying if you leave autoranging on while probing stuff >1.2V - the Agilent has no audible relay as far as I can tell. My bench is rather loud though with several high end PCs running so the fan noise might drown it out. At lower resolution like 4.5 digits, both meters are too fast to be able to see the readings before the change. The Agilent can do 1K/s, and the Picotest can do 50K/s - both are more than adequate for my purposes. In terms of other measurements, the Agilent is quite limited with only the basic functions, while the Picotest has capacitance and temperature (with a bewildering array of sensors and thermocouple types) - no point talking about those as I cannot compare what the Agilent does not have. The diode check on both meters are quite limited, and unable to measure more than simple diodes. They fail to measure a number of LEDs I tried, and cannot cope with zeners >2V. This is true of both meters. The continuity of the Picotest is absolutely rubbish, it is latched but has a ridiculously long hold time before it beeps. The Agilent is much better in this regard, but it too is not very good. I will likely never use this feature because of how slow it is compared to my other (handheld) meters. I work mainly with FPGA boards, and finding continuity by dragging is a useful technique that would be significantly slowed down by either of these meters. I have no high quality frequency reference, but I checked against my cheap Chinese AWG and both meters live up to their (modest) claims. The kelvin ohms measurements are also in agreement, but I don't have any reference resistors to check the accuracy.I will post more as I discover more

author: supercilious
author_rank: Contributor
timestamp: March 01, 2016, 12:53:43 pm
content: TLDR Pros & Cons:Picotest:+ I am thoroughly impressed with the ease with which I was able to get up and running with the Picotest - simply installed the VISA drivers and plugged it into my USB hub.+ It can do dual measurements, in particular, current and voltage is a very useful one.+ Thermocouple measurement (K-type) is more accurate than even my dedicated thermocouple data logger - and can be done simultaneously with other measurements.+ Separate jack for thermocouple so I can leave one connected permanently.+ 50K readings/s @ 4.5 digits.+ Its fast, even at the full 6.5 digits.+ 10A range.- Ridiculously slow continuity test. Useless.- It takes a few minutes of warmup to start reading accurately. ~5mins is enough for my cheap references.- It has loud clicky relays that switch its DCV ranges between 1v and 10v, so are very frequently triggered when measuring most things.- It has an awfully tacky looking LCD screen.- Current ranges require swapping leads between 3A and 10A.34401A:+ It gives a stable immediately from power-on without any warmup - at least as far as I can tell from my crappy references.+ It has jacks on the back so I can always leave a pair of kelvin clips connected or whatever, instead of having to swap leads every time.+ Its quiet (at least compared to the ambient noise in my workspace). No audible relay clicks.+ Widely supported, so calibration and servicing is cheap.- It has only a 3A current range.- GPIB is annoying to interface with modern machines.- 1K readings/s maximum acquisition rate; only 2-3 readings/s at full resolution.- No "fancier" measurements like capacitance or temperature.- No averaging filter for DCV (I might be wrong about this, but I can't find how to operate it)EDIT: Fixed typos.

author: Performa01
author_rank: Super Contributor
timestamp: March 01, 2016, 03:08:30 pm
content: Wow - there are a few unexpected findings...At first I want to point out that I don't have experience with any of the two meters. Amongst others, I do have a Picotest M3500A and Keithley 2015 THD (which I figured should be very similar to the 34401, according to the specs).The M3500A used to be my darling meter when it comes to precision measurements, not only because of its low noise and great short term stability, but also the USB interface and great remote support. There is no difference between all the Picotest meters for sure, so your experience with easy PC connection wasn't a surprise for me.I never looked at the continuity test at any of these meters, not even sure if the K2015 has one; I really don't think a lab grade 6.5 digit meter should be abused as a continuity tester - I use my trusty Fuke 45 for that - and this one is blazingly fast at this.A warm-up period is needed for every meter; still the higher accuracy ones will have a stable (heated) reference, so once this is heated up after a few seconds, nothing much changes after that - certainly less than 10ppm. The M3510 probably doesn't have an ovenized reference, so the warm-up period is much more noticeable.I for one don't mind a little acoustic feedback from an instrument, like clicking relays. I passionately hate fans that are permanently running though, which seems to be pretty much standard with any newer instruments nowadays.Yes, from the brochure, the display doesn't look very sexy - whereas the one on the M3500A is superb.The separate 10A jack is pretty much standard, as it usually means a separate shunt and fuse.For lab grade meters, ranges >2A are quite unusual anyway. Due to the massive heat the usual practice is to measure the voltage drop across an external shunt whenever high currents are to be measured (or use a current clamp).I hate GPIB too - because it usually means that it is the only option to talk to the instrument. This is where modern instruments really shine - they have USB (and sometimes even LAN) as standard and GPIB as option. And the USB-GPIB adapters aren't exactly cheap and might still give you headaches...What really surprises me is that you seem to suggest the 34401 cannot do more than 2-3 readings at 6.5 digits; both the K2015 and the Picotest M3500A can do 50/60 readings per second at full resolution (at 1NPLC, depending on mains frequency). I almost cannot believe that the famous 34401 should be such a lame duck - are you sure about that?Well regarding capacitance measurement, I don't see the point in having that, to be honest. What DMMs are offering in this regard is misleading at best. There's no way this could ever replace a proper LCR/ESR meter and only these will allow you to judge the true qualities of a capacitor.I'm surprised again to learn the 3401A doesn't do temperature measurements? So it seems I was wrong when assuming that K2000 and 34401A were pretty much the same from a users perspective...For your last point I'm pretty sure you've missed something. It might not be called 'filter', but you should be able to set the NPLC value? This would have the same effect when you set it to a higher number like 10 or even 100.

author: supercilious
author_rank: Contributor
timestamp: March 01, 2016, 04:15:09 pm
content: Quote from: Performa01 on March 01, 2016, 03:08:30 pmYeah, that was a pleasant surprise. I anticipated having a harder time getting everything interfaced, but it pretty much just workedQuote from: Performa01 on March 01, 2016, 03:08:30 pmMe too. I never expected to use either of these meters for such a purpose, but I tested this functionality anyway. I actually use a custom built continuity tester for for probing really sensitive stuff. I couldn't find anything that reliably worked with really low voltages and tiny currents. Since I work mainly on FPGA boards, even the typical 1v continuity mode of most meters is enough to do some damage, so I built myself a 250mv tester that pushes around 50nA and latches instantly. Just enough voltage to avoid false triggers from ambient noise picked up by the comparators.Quote from: Performa01 on March 01, 2016, 03:08:30 pmI don't think either meter has an ovenised reference, but I would love to know more about their internals. I haven't torn either one down, and I probably won't unless something breaks, but I understand that they both use an LM399. I'm not an expert on this matter, but the 34401A instantly gives exact readings (to the limits of my references), whereas the Picotest takes a few minutes before it does so.Quote from: Performa01 on March 01, 2016, 03:08:30 pmI certainly don't mind the relay noise too much, but I would definitely prefer not having it. I used to have an old linear power supply which used loud clicking relays to switch transformer taps and I think it made me hate that sound. One of the best things I ever did was replace that supply with the Rigol DP832 which uses nice silent triacs.Quote from: Performa01 on March 01, 2016, 03:08:30 pm"Not sexy" is putting it mildly. Switching from a set of nice 4K monitors to look at those horrid screens on test equipment is... an adjustment. I will be glad the day they make an affordable oscilloscope which can stream its ADC data directly to my PC at the full sample rate. Electronics and hardware development people are stuck in the stone age when it comes to software. Life would be indescribably better if I could have the raw sample data in real-time rather than a silly low-resolution picture of the data. Dave's recent video where he described a 1M FFT as needing a powerful processor literally made me laugh out loud, this is the kind of mind-warp that happens when you spend too much time with tiny microcontrollers.Quote from: Performa01 on March 01, 2016, 03:08:30 pmThis is not a big issue, but I would much prefer not to have to break out a shunt resistor every time I make such a measurement. I typically only use high current measurements to figure out where to look, so I quickly move on to other measurements. I bought a cheap Hantek CC-65 current clamp so the 10A range is even less important, but its nice to have the option nevertheless.Quote from: Performa01 on March 01, 2016, 03:08:30 pmYes, this has been the single most annoying aspect of the 34401A. I cannot get the damn GPIB working... grr.Quote from: Performa01 on March 01, 2016, 03:08:30 pmNo that was ignorance on my part. I did manage to set the NPLC to something more reasonable, but I have to say the front-panel interface is massively better on the Picotest. Having dedicated direction buttons and enter and esc buttons makes this much nicer to navigate menus.Quote from: Performa01 on March 01, 2016, 03:08:30 pmI'm not particularly bothered by the lack of capacitance or temp measurements on the Agilent, but its nice to have it and not use it regardless. The 34401A definitely does not do temperature measurements as far as I can tell. I haven't looked at the datasheets, but I can't find any such modes. The picotest thermocouple measurements accuracy impressed me sufficiently that I will be replacing my dedicated thermocouple data logger for most uses since the picotest gives me a high resolution and better accuracy for temperature measurements, and since I can use it as the secondary measurement, it won't impact the normal use.As I said in my earlier post, I have only had these meters since yesterday and I have spent most of that time figuring out how to get the GPIB interface working. I will look into the rest once I have the basics up and running. Overall, my assessment of both meters is that they each have their place. If I could have only one, I would certainly pick the Picotest since it actually works out of the box thanks to its USB interface.EDIT: Fixed botched /quote

author: Performa01
author_rank: Super Contributor
timestamp: March 01, 2016, 05:21:02 pm
content: Well, the LM399Hisan ovenised reference and standard in pretty much all these meters - except for the very high end ones, starting at 7.5 digits. It's just the rather mediocre accuracy specs of the M3510 that makes me think it has something diferent. We certainly cannot get schematics for these newer meters like the Picotest, but the old ones in a similar accuracy class (like e.g. Keithley 195A) just have reference diodes without heater.Anyway, I'm really glad to hear you like the M3510A - as there are many folks who disregard anything other than Keysight or Fluke as useless junk from the far east. Yes, as mentioned several times already, the M3510 isn't in the same class wen it comes to accuracy, but when buying new, it is by far the cheapest option if one wants 6.5 digit resolution. Since not every task requires accuracy that high, but many would benefit from the high resolution, this instrument has its place for sure. I read quite a lot here in the T&M section of the forum and already started wondering if I'm actually the only person in the world using (and loving) a Picotest meter...Anyway, enjoy your new toys and fingers crossed you'll get that annoying GPIB issue sorted pretty soon!

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: March 01, 2016, 07:36:23 pm
content: I have a Kiethley 2100 (supposedly rebranded Picotest M3510A ).With any of the modern firmwares it is an excellent meter. It is very, very fast. No communications issues. The Continuity tester is as fast or faster than a Fluke 87V. Dunno why people thought it was slow.. unless that was a really old firmware. You would be hard pressed to get it to miss. You can adjust the beep level as well, up from the default 10 Ohm, if you have some crappy test leads or something.This meter got a bad rap early on due to the initial firmware bugs. Everything has growing pains with early firmware these days. Sure, it is a rebrand, but it is priced like a rebrand.Overall the UI on the meter is decent, but not great. I wish I could turn off the display without having to go to config->System->display. I wish a few more settings were stored through power cycles. Most settings are restored to default, which can be useful, but it would be better if it stored its current settings, but had a "reset defaults" button.For USB, the KI-Tool software is adequate for logging, and showing a basic graph. It is not a brilliant piece of software, but it works. I wish you could resize the window larger. If anyone has any better PC software for use with these meters let me know.I got mine off ePray for about half of list price. If you are having trouble upgrading the firmware be sure you have the latest updater from the US Kiethley site. I originally tried the one off the UK site, which was out of date (the UK site did not require I create a (free) login).

author: supercilious
author_rank: Contributor
timestamp: March 01, 2016, 07:59:02 pm
content: I'm certain that the M3510A uses an LM399 reference, I saw it in a set of teardown photos. I don't know which revision though, I'll try to look it up again.As for the continuity, I am surprised that the 2100 does it that well because the Picotest has one of the slowest ones I have ever used... Its not the test leads as I tried the same ones on another meter and got far better results. Its not a big deal anyway as I will likely never use it, but it would be nice to have all the other firmware issues resolved too, including the ones I have not run into yet. I'll look into upgrading the firmware.On the software side of things, I mainly use my own little library of code to visualise readings from my various devices. I have a set of python scripts that log readings (with an associated timestamp and label) to a database, either sqlite or postgresql. I then have another Qt based program which polls the database and draws various graphs and histograms based on that data continuously. Its really simple to write, and getting the data into the PC is the hardest part. I wrote the acquisition part separately so I can leave it running 24/7 even on a little raspberry pi or odroid while the bigger beefier PCs do the number crunching.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: March 01, 2016, 08:31:34 pm
content: Quote from: FlyingHacker on March 01, 2016, 07:36:23 pmI'm pretty sure that Array is the actual OEM for these devices.

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: March 01, 2016, 09:09:47 pm
content: That is really odd about the continuity. I just tested it on the 2100 (1.0.8 firmware). It was at least as fast as my Fluke 87V. It actually may have been faster. I tested both meters with the same Fluke probes.Perhaps the Kiethley is more than a rebrand. I have not opened it up.Do you know any good sites describing how to get the Python readings working? I don't have a lot of experience with reading remotely other than logging with KI-Tool under Windows. I suppose I should possibly hook it up to a pi or other linux machine. Likely much easier to set up. I now that sounds odd that linux would be easier to setup than Windows, but I think the package manager would handle the dependencies for you. On Windows it is not always clear what is missing.

author: supercilious
author_rank: Contributor
timestamp: March 01, 2016, 10:27:05 pm
content: It is surprisingly easy. I have only personally ever used Python for simple stuff and C++ where performance matters, but there are VISA interface libraries for many many languages. My acquisition system is actually running Windows 8.1, but I did test with a Linux box too (in a VMware virtual machine).https://pyvisa.readthedocs.org/en/stable/

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: March 01, 2016, 11:48:40 pm
content: Cool. Thanks.

author: Performa01
author_rank: Super Contributor
timestamp: March 02, 2016, 05:42:17 pm
content: The Keithley 2100 is a rebranded Picotest M3500A, not 3510. The M3500A is the one I know and have and love (more so than e.g. the Keithley 2015 THD).As for the data logging, I've already mentioned the Excel macro, which is much more versatile than the provided stand alone application. With the macro, one can obviously make the graph window as large as they want.

author: supercilious
author_rank: Contributor
timestamp: March 02, 2016, 06:09:16 pm
content: I may be wrong, but as far as I know, excel is limited to about 2^20 (~1m) rows, which at the full sample rate is just around 20 seconds worth of readings. I doubt an excel macro can even consume data that fast anyway, but things may have improved in that regard since Office 2010.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: March 02, 2016, 07:18:28 pm
content: Quote from: Performa01 on March 02, 2016, 05:42:17 pmWhich is a rebranded Array M3500A, I suspect the M3510A is from Array as well but I have no proof on that. Array is the OEM for a range of stuff including digital loads and a few older power supplies. I think they have been crippled of late because their lead engineer left to found Maynuo (which sells DC loads which are very similar in technology to the iTech/BK Precision and Array loads they are based off of (this engineer worked for iTech first, then Array and now Maynuo), but just updated).

author: FlyingHacker
author_rank: Frequent Contributor
timestamp: March 02, 2016, 10:47:30 pm
content: Quote from: Performa01 on March 02, 2016, 05:42:17 pmI see. So your M3500A has lightning fast latching on the continuity tester like my 2100?

author: markone
author_rank: Frequent Contributor
timestamp: March 02, 2016, 11:59:16 pm
content: Quote from: supercilious on March 01, 2016, 12:53:43 pmHisupercilious,interesting review / comparison , i have some questions about dual measurement with DC current & DC voltage on Picotest :1) are they in phase or alternatively scanned ?2) which actual refresh rate can i obtain ?3) meas scale range should be fixed or could be left in auto (at least for current) ?

author: supercilious
author_rank: Contributor
timestamp: March 03, 2016, 01:39:07 pm
content: Quote from: markone on March 02, 2016, 11:59:16 pmThey are scanned alternatively, as there is only 1 ADC in this meter.Quote from: markone on March 02, 2016, 11:59:16 pmYou can set the PLC count it uses. It maxes out around 5-6 readings/sec for DCV+DCI. You can hear the relay clicking back and forth as it switches sources.Quote from: markone on March 02, 2016, 11:59:16 pmFor DCV+DCI specifically, you can set the range manually to 1A, 3A or 10A. For most others like DCV+ACV you can leave it on auto. You get the full 6 1/2 digits on both though (optionally).Many of the measurements do not cause any noisy relay clicking (which annoys me a bit, personally) like the thermocouple measurements.

author: Performa01
author_rank: Super Contributor
timestamp: March 03, 2016, 03:52:31 pm
content: Quote from: supercilious on March 02, 2016, 06:09:16 pmWell, that Excel macro doesn't work like an LF oscilloscope, you only get one reading per second maximum - just like the stand-alone application does. So if someone's major concern is the diagram size in that application, the macro is the obvious cure for that.

author: Performa01
author_rank: Super Contributor
timestamp: March 03, 2016, 04:02:20 pm
content: Quote from: FlyingHacker on March 02, 2016, 10:47:30 pmI think so, but as I've mentioned before, a highly precise 6.5 digit meter is too good (for me) to be used for continuity checking, i.e. I have a 4.5 digit DMM which is in continuity mode pretty much all the time, so I just grab its test leads whenever I want to check something.To cut a long story short, it's been years since I last tried the continuity mode on the M3500A, but will try it this weekend and report back should it turn out to be anything other than 'blazingly fast'

author: markone
author_rank: Frequent Contributor
timestamp: March 03, 2016, 09:54:52 pm
content: Quote from: supercilious on March 03, 2016, 01:39:07 pmMany thanks for exhaustive answer,so like almost quality bench DMMs it uses a relay to select voltage / current signal source, but with 5-6 paired meas / s seems pretty fast.Noise and relay's life expectancy apart, it would be not a good idea to leave it in fast scanning mode for hours by day, i have to find an alternative solution.Anyway it looks fine for ATE benches, i will keep in account for future works.