scope suggestions, solutions with floating isolated inputs.    - Page 1
Forum section: electronics / testgear

author: wizard69
author_rank: Super Contributor
timestamp: January 08, 2022, 05:35:31 am
content: Simply put looking for the known vendors of scopes with isolated inputs (4), hoping somebody has a list. I know about the Fluke 190 series but have to imagine there are other credible competitors.The usage is industrial, high speed packaging, CNC hardware, motor drives and such. It has come time to try to convince the boss to spring for a new instrument.

author: bdunham7
author_rank: Super Contributor
timestamp: January 08, 2022, 05:48:14 am
content: There's the Tektronix TPS2000B series, lunch-box style with batteries. About $6500 for the 200MHz/4ch TPS2024B, that doesn't include the second battery or the insulated probes for $385....each. I think the power analysis software is another $1500 or so. The scope works well but is pretty basic--2.5k points, no advanced trigger options. It is essentially a 20 year old design, so if you like expensive retro, it is for you.For any type of field use, I think the Fluke is the way to go, but you can also look at the Rohde & Schwarz RTH series.

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2022, 06:10:55 am
content: Updated 2ch SHS models are not far away and their isolated model range is SHS1000X with 1 GSa/s and 12 Mpts mem depth. 70, 100 and 200 MHz models will be available however we don't yet have pricing or an ETA to western markets.Specs other than those mentioned above will be similar to these:https://int.siglent.com/products-overview/shs1000/However the new X models will have I2C, SPI, UART，CAN，LIN decodes.

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 08:27:26 am
content: Quote from: bdunham7 on January 08, 2022, 05:48:14 amI would recommend against the fluke. The 190 and 200 (color) series are VERY basic scopes. We use them at work, but for most interventions that required a scope, I always wished it had more features (larger memory, more triggering options & more channels are the main issues for me).The R&S offering seems quite a lot better, but I have not used it. For machine debugging the lowest bandwidth is more than adequate in my experience (typically you need to set a bandwidth limit filter anyway), but I would definitely recommend 4 channels, as you typically need already one channel for triggering on the "correct" moment when the problems occurs, and this leave only 1 channel to see "why" the problem is occurring.Another option is the Picoscope 4444. This off course also requires a laptop, but I am typically also looking inside the plc software, for me that is not an issue. We recently bought a 4444 at work with both current and differential probes. I have not used is extensively, but it does what in need to do on the few occasions I used it so far. For sure miles ahead of the Fluke. Main reasons we choose the 4444 instead of the R&S offering was the higher resolution and the picolog capabilty to log measurements over extended periods of time. But the R&S was very tempting also.

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 08:32:44 am
content: Quote from: bdunham7 on January 08, 2022, 05:48:14 amFor me this is also applicable for the flukes

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 08:41:08 am
content: Quote from: tautech on January 08, 2022, 06:10:55 amLooks for sure a better option than the fluke, but would prefer more channels (even if it were only a digital 24V capable channel).For machine debugging, you typically use a sensor or plc output as the trigger condition. A pattern trigger I whished for many times, but for that you need many channels. A typical workaround is to program some additional code (the pattern) in the plc and trigger the scope via an unused plc output. But as I often work in regulated environments, were program changes are not allowed without a lot of paperwork, that is not always an option.

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 09:02:59 am
content: Quote from: wizard69 on January 08, 2022, 05:35:31 amEven more useful than a scope in many occasions, is a high speed camera to see exactly what is happening. Often automation trips are a masked mechanical issue, and this is not easily spotted with a scope. I also often use plc analyzer software to plot many signals simultaneously if the high speed of a scope is not needed.

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2022, 09:14:47 am
content: Quote from: _Wim_ on January 08, 2022, 08:41:08 amI quite agree however these days with very capable 4ch scopes for $500 plus even a set of four cheap 25 MHz DP-25 differential probes total cost is under $2k which will meet most technicians needs.It's been my view Siglent is barking up the wrong tree when instead they should be putting their isolated front end into a compact benchtop as they are certainly portable enough.In fact I lobbied hard for such an instrument some years back however they set their sights on higher BW models rather that take the opportunity to grab this market sector from Tek.

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 09:28:23 am
content: Quote from: tautech on January 08, 2022, 09:14:47 amI can agree that this would be a good solution also, but some companies will not allow this because it is not inherent CAT-III of CAT-IV and as such can be incorrectly used by the technician creating a possibly dangerous situation.Quote from: tautech on January 08, 2022, 09:14:47 amI agree with that. This is essentially what the Pico scope 4444 also is, and it makes perfectly sense. It was a good choice from them to use sub-D9 connector inputs, because this does not allow to connect a "standard" probe, only their rated accessories. As machines become higher and high both in speed and complexity, industrial scopes will be a growing market in my opinion.

author: tautech
author_rank: Super Contributor
timestamp: January 08, 2022, 09:52:26 am
content: Quote from: _Wim_ on January 08, 2022, 09:28:23 amYet perfectly safe probes are BNC types and especially designed for isolated channel scopes so NO I won't buy into that.https://siglentna.com/download/14761/Sorry shit pic

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 10:16:56 am
content: Quote from: tautech on January 08, 2022, 09:52:26 amBut these probes do not make the scope + probe combination CAT-rated and isolated. The probes used on the 190-series are similar to what you show. As we have currently around 10 of those 190/200 series scopes floating around the company, probably many more of these probes are floating around.Say we want to switch now to a more capable scope and we consider a Siglent + 4x DP-25. Currently our technicians are used to the fluke 190-series were you can probe wherever your want, both for ground and signal.Now they are using the new Siglent with DP-25. But they do not find the correct accessories for the banana jacks on the DP-25, but do have some of those old fluke probes in they tool box. So they opt to use that instead on the Siglent and start probing not choosing ground carefully or try to measure on a busbar to look for spikes...This is not uncommon within a industrial setting. Scopes are use by both novices and experts. You always want to prevent situations as described above.

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 10:29:01 am
content: And yes, I am aware the Pico scope is also not as robust as the Fluke in the above scenario. But at least it is a step closer. The R&S is still the safer option if more capability is required. But many of its additional capability is an option, so you end up with an 8K+ scope that still does not do much more and an average 1K bench scope.I really do not understand why R&S did not foresee more memory depth. As typically you do not know what the problem is (otherwise you would not be probing but just fixing it) and it can be difficult (and expensive) to simulate the issue the machine has, you want to catch the issue as fast a possible. For this your need much memory so you can capture a large time frame that is still zoomable to the problem, and many channels, so you can probe all possible culprits at once. The second part they covered with the logic analyzer + 4 channels, the first part with only 500K still needs some work.

author: Fungus
author_rank: Super Contributor
timestamp: January 08, 2022, 11:18:50 am
content: Quote from: wizard69 on January 08, 2022, 05:35:31 amGet 4 differential probes instead, it will bemuchcheaper.eg.http://www.micsig.com/html/41.html

author: nctnico
author_rank: Super Contributor
timestamp: January 08, 2022, 11:32:16 am
content: Quote from: wizard69 on January 08, 2022, 05:35:31 amMaybe Yokogawa has something interesting in their lineup. The used to have th DL807 / DL716 series with input modules and for these there are modules with floating / differential inputs. Much of Yokogawa's oscilloscope offerings is aimed at motor control / power / vehicle / mechanical nowadays.This could be an interesting option:https://tmi.yokogawa.com/solutions/products/oscilloscopes/scopecorders/dl950/Or this:https://tmi.yokogawa.com/solutions/products/oscilloscopes/scopecorders/dl350-scopecorder/

author: wizard69
author_rank: Super Contributor
timestamp: January 08, 2022, 12:54:12 pm
content: Thanks for the direct at Picoscope, they never occurred to me.As to channels I'd really would like 4, or two with a trigger input. I'm currently working on an issue where we use that trigger and the two channels and frankly I'd like another. Fortunately in this case I can get by without the isolated channels but that isn't always the case. Plus we have a number of new techs that just don't have the experience.I did manage to find some info on Keysight options but they really don't have what I want (channels)Quote from: _Wim_ on January 08, 2022, 08:27:26 amI understand this completely and frankly it is sometimes the simple things that make the difference. For example being able to easily get data from the scope, print a trace or having preset configurations can make for a more usable scope.QuoteYou apparently have some of the same sorts of issues I have, a simple 2 channel scope doesn't cut it.QuoteThanks for the heads up.

author: wizard69
author_rank: Super Contributor
timestamp: January 08, 2022, 01:03:26 pm
content: Quote from: _Wim_ on January 08, 2022, 09:28:23 amInterestingly we do use an isolation probe from time to time. Or I should say I do, but in all honesty I'm nearing retirement and would rather leave the youngsters with a safe compliant device. Currently these tools are shared between the technicians and the engineering group and honestly I don't trust either group to engage in safe practices.QuoteSadly the biggest problem with a PicoScope isn't their hardware but rather our IT department. IT is locking down computers way too hard. Personally I'd lean strongly to such hardware simply for flexibility, the potential in teaching and data collection

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 03:36:58 pm
content: Quote from: wizard69 on January 08, 2022, 01:03:26 pmYes, that is indeed becoming more and more a problem. Currently we are still allowed to use Siemens Field PG's (https://www.s7automation.com/product/simatic-field-pg/) for our automation tasks, which are not IT controlled (but are also not allowed to connect to internet, industrial LAN's or business LAN's). We run the Pico software from one of those. However, since most automation hardware is more an more accessible via network, Field PG's are being replaced by virtual engineering stations, which are fully IT locked.For me it still seems contradictory that IT considers a Picoscope with dedicated laptop "dangerous", while a typical benchtop instrument is exactly the same: a pc with an acquisition module built in.The R&S with 4 channels seems a good alternative, but only is price is not really an issue.

author: _Wim_
author_rank: Super Contributor
timestamp: January 08, 2022, 03:44:29 pm
content: Quote from: wizard69 on January 08, 2022, 01:03:26 pmYes, similar situation here. This is why the Flukes are great, they are very simple to operate and reasonably safe in the typical machine control cabinet (and luckily all mid and high voltage cabinets are locked and require a specialized training before entry is allowed). But when we have to come in for the more complex issues, I am glad we have now the pico 4444 for the more complex tasks.

author: Momchilo
author_rank: Regular Contributor
timestamp: January 08, 2022, 04:39:47 pm
content: In my opinion one of the best or the best scope for that purpose is theCleverscope CS448.The only disadvantage is that it's a USB scope without display. So you need an additional laptop and the scope isn't super cheap. But the price is very fair for the functionality.

author: shakalnokturn
author_rank: Super Contributor
timestamp: January 09, 2022, 03:10:15 am
content: https://www.aemc.com/products/oscilloscopes/OX93044 channel 300MHz so not the cheapest in the family, probes are also specific and expensive.

author: TheSteve
author_rank: Unknown
timestamp: January 09, 2022, 03:41:41 am
content: The Tektronix THS3024 is prettyedit - and also discontinued...

author: _Wim_
author_rank: Super Contributor
timestamp: January 10, 2022, 06:41:07 am
content: Quote from: shakalnokturn on January 09, 2022, 03:10:15 amBut still cheaper than the flukes, and 4 channel and quite a lot of extra features. Not as advanced as the R&S, but also quite a bit more affordable. Good suggestion!

author: _Wim_
author_rank: Super Contributor
timestamp: January 10, 2022, 06:49:23 am
content: Quote from: Momchilo on January 08, 2022, 04:39:47 pmThis seems certainly a very capable scope, but more geared towards development of power electronics than machine debugging in my opinion. It also appears it not yet officially CAT-rated, which would be an issue for the company I work for.

author: 2N3055
author_rank: Super Contributor
timestamp: January 10, 2022, 08:17:06 am
content: Quote from: TheSteve on January 09, 2022, 03:41:41 amThat is pretty much just a rebrand of Fluke 190 ScopeMeter

author: simba15
author_rank: Regular Contributor
timestamp: January 10, 2022, 06:42:31 pm
content: My previous work was in power electronics ( mostly VFD's) where the PWM voltage could be in the 1000s range,The previous industry standard was the THS720p (but this was very old and very poor pc software and poor waveform capture.)I upgraded to the R&S RTH1004, this was fully isolated with large screen and lots of connectivity options.The only issues I ever had was when very noise signals were measured , I had to turn the touch screen off or we would get erratic presses.

author: wizard69
author_rank: Super Contributor
timestamp: January 11, 2022, 05:37:56 pm
content: Quote from: _Wim_ on January 08, 2022, 09:02:59 amIn this case it was a hilarious number of issues due to "new" guys not understanding how to work on the machine. In part that is due to the lack of good documentation. However once I got past the configuration issues and other mistakes, I was able to setup timing properly. It would have been far easier with a 4 channel scope with a trigger input which is why this post exists.

author: wizard69
author_rank: Super Contributor
timestamp: January 11, 2022, 06:08:24 pm
content: I'd like to thank everybody for their leads. I was rather surprised that HP really didn't have a suitable cat rated scope for this usage and the Flukes while nice don't leave me with a lot of known options. Now that I know about the R&S series they are at the top of the list and actually look like a much better choice than the Fluke models. At least at this moment in time, I haven't done a lot of in depth yet. i also need to check out a few of the other mentions here.In any event the reasons for dismissing some suggestions are as follows.USB connected scopes might be good for personal use but our IT department at work has made practical use of a PC just about impossible (driving me to early retirement). This is actually a huge frustration because it isn't uncommon to need to install/update software every couple of months.The problem with external differential probes is that the variety of potential users makes in nearly impossible to know that they will be used properly. Like the suggestion of a USB scope it would be fine for a personal device but I'd rather not have to "HOPE" that people would use the probes properly. It is actually worth it to me to know that it will be extremely hard for the user to harm themselves with the scope. How the company feels about this is mixed, I'm actually surprised that the safety department does not stick their noses into our instrumentation.As you may all know, much of industrial automation does not require wide bandwidths for most of the serviceable systems. However we do have some RF powered tools that might benefit from a more capable scope. In all honesty though most of that stuff just goes back to the manufacture as does most of the lab equipment. Still the old scope is 100MHz so I'd like similar performance which seems to be easy to obtain.So I hope you all understand why some ideas will not go far. The issue with IT is really troublesome as in many cases it causes people to implement technology that has no place in a modern manufacturing environment. It really feels like a step backwards in some regards. My Apple Mac Book Air is no more useful at work than the PC's we get issued.Thanks everyone for the help.

author: _Wim_
author_rank: Super Contributor
timestamp: January 11, 2022, 07:21:09 pm
content: Quote from: wizard69 on January 11, 2022, 05:37:56 pmAh, you also have these guys who think that they need to adjust "everything" to make it run "better". Always fun to get the machine up and running again after such an adjustment round...

author: graybeard
author_rank: Frequent Contributor
timestamp: February 08, 2022, 02:36:22 am
content: I recently purchased a niceTektronix THS720Pwith aFluke Y8100 current probeplus Chinese scope probes and meter leads. for $300 from fleabay.It had large offsets in all of the input ranges that were not corrected by doing the signal path compensation. However once I put it through thevery simple scope calibration procedureit works great! The only instruments I needed for the calibration was myPDVS2mini,Siglent SDG2000X function generator, a50 Ohm feed through termination, and BNC tee, two BNC to BNC cables, and one BNC to dual banana cable.I boght the THS720P version over the other available model because of it's built in ability to calculate power factor and measure power harmonics that the other models in the line do not do. I hope to use it in a video soon.I have a 500 MHz battery power scope aTDS3012B that I "upgraded" to a TDS3052B, but the input channels are not isolated from each other. The THS720P adds some unique capability to my home lab at what I think was a very reasonable cost.Like most of my ebay purchase I waited months for this deal to come up. The Fluke current probe was a nice bonus.