# Need advice on a USB MSO, DAQ, or LA purchase.

Discussion in 'General Electronics Chat' started by strantor, Mar 20, 2014.

1. ### strantor Thread Starter AAC Fanatic!

Oct 3, 2010
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That is, Mixed Signal Oscilloscope, Data Acquisition unit, or Logic Analyzer, that interfaces with a computer via USB, serial (preferably not), or Ethernet. If you've used one and can give first hand testimony, that's great; or, if you've just heard of one that's good, that's great too. I've googled these things extensively, but I may have missed some. FYI I'm running Windows 7 on a more-than-capable laptop.

I have future needs (see below***) but My immediate need is for a device that I can use to troubleshoot intermittent and/or brief glitches in machine control circuits. Usually I'm looking for noise on comms busses, brief digital signal drop-outs or analog signal under/over events, or overall sequence of several digital and analog signals. I would like the device to replace my current oscilloscope as well; I mainly use my scope to measure the output of encoders and Variable Frequency Drives.

I have prepared a color-coded list of needs/wants in order of importance. Needs start at the top and taper off to wants at the bottom. Needs end and wants begin, in a fuzzy sort of way (grey area), denoted in orange:

• Ability to monitor 24VDC and 120VAC digital machine logic signals.$^{*1}$
• Ability to monitor +/-10V and 0-20mA analog signals
• At least 2 analog channels
• Electrical Isolation from USB port (alternatively I could probably use a USB isolator, not sure)
• "strip chart"-type mode for plotting various signals (aspects of signals; ex: frequency, amplitude, duty cycle, et. al.) over long time periods, with ability to zoom in on blips/areas of interest.
• Capable of measuring up to 1KV, 30kHz PWM VFD output, and plot this along with my digital/analog signals.
• Powerful & easy to use software interface (Not limited in features, but also not confusing)
• 8+ digital channels
• 16+ digital channels
[*]High bandwidth and sampling rate, huge buffer
[*]low cost
[*]At least 3 true scope channels with BNC connectors.
[*]Ability to leave the device connected to the circuit under test in data logging mode, without laptop, for days$^{*2}$

[*]Documentation clear and not in Chinglish
[*]Ability to plot calculated math traces in real time via user input formulas or scripts.$^{*3}$
[*]Integral function generator
[*]Multi-channel digital signal generator with ability to record digital signal traces in Logic Analyzer mode and then "play back" into the circuit under test in signal generator mode
[*]USB3.0
[*]User-settable trigger conditions (ex: trigger when DI1 is high, DI7 is low, and AI3>AI1)
[*]Ability to export data to excel
[*]Ability to read & plot thermocouple, strain gauge, and resistance input.
[*]Network and/or wireless Connectivity
[*]Android/Apple app to view data on mobile device over ^ Network and/or wireless Connection
[*]User programmable
[*]Packet analyzer
[*]Spectrum analyzer

If you have a short attention span, stop reading now and reply.

NOTE: 50% of the above list (mostly near the bottom) was compiled from bullet points on various MSO adverts that sounded cool, or I just made up features that I want to see. I'm not a super experienced Oscilloscope or Logic Analyzer user so I don't have a strong handle on what's actually important, though I did read this. So if you think my priorities are mixed up, let me know; they probably are, and I would be glad to rearrange them.

$^{*1}$. I have pretty much resigned myself to the fact that I am going to have to build some sort of opto-isolation box between the machine control circuit and the MSO since none of the units I'm seeing support these voltages directly, and none of them can take an AC signal on the digital inputs.

$^{*2}$.It would be cool (meaning, pie-in-the-sky desired, but not required) if the device could be connected to the signals of interest and then disconnected from the PC and left in place, monitoring, possibly for a period of several days; either a sizable internal memory would be required, or a programmable trigger (ex: on loss of a certain signal) - this can easily be done with a brick PLC, which I have done in the past and have little qualms about continuing the practice, but it would be cool if the device could do this (with better resolution than a PLC and a pretty data trace) as well.

***My future need (as I delve further toward the depths of nerddom) is for a high speed, full-featured logic/protocol analyzer than I can use for designing electronics.

I'm looking at stuff like this:
Picoscope
Cleverscope
USBee
Quantasylum
Rigol DS1000 series

NOTE: I'm not 100% opposed to the idea of a non-USB device (see the Rigol link above), however I strongly prefer USB, and most of the benchtop units I see are prohibitively expensive.

I have a budget in mind, but I won't state any dollar amount because I don't want to limit the feedback. Let's just say it's probably higher than the typical hobbyist budget but less than the infinite budget of a megacorporation. The less expensive the better.

Right now I'm leaning toward the Bitscope BS325. The software looks very sleek and it seems like it can do just about everything I want it to do. The only things holding me back are the following specs:

Hardware Sample Rates: 15kSa/S to 40MSa/S (Is this sufficient?)
Capture Buffers: 512kS x 2 (analog) plus 512kS x 8 (logic) (Is this sufficient?)
Capture Resolution: 8 bit converter with 6.8 to 7.6 ENOB (Is this sufficient?)
Maximum Resolution: 13 ENOB (at 1MHz and lower) (Is this sufficient?)

2. ### strantor Thread Starter AAC Fanatic!

Oct 3, 2010
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$^{*3}$Example of what I mean by user input formulas: User clicks a button that says something like "Add new math trace," is prompted by a single line text entry dialog popup for a name and enters:
Code ( (Unknown Language)):
1. Calc'dTace1
User clicks "OK," and then is prompted by a second single line text entry dialog popup for a formula and enters:
Code ( (Unknown Language)):
1. (AnalogCH1 + AnalogCH2) * 3.14
Example of what I mean by user input scripts: User clicks a button that says something like "Math trace script panel" and a multiline text editor appears, where the user enters something like :
Code ( (Unknown Language)):
1. If DigitalCH1=1 & DigitalCH3=0 & AnalogCH3<3.4V then
2. Calc'dTrace2= (((AnalogCH2 +1)/freq(DigitalCH5))*sqrt(duty cycle(DigitalCH8)))
3. else Calc'dTace2= (RMS(AnalogCH2))
(most extreme hyperbolic example I could think of - total nonsense, but conveys the point)

3. ### R!f@@ AAC Fanatic!

Apr 2, 2009
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How much does bitscope cost ?
And what in freakin name is Chinglish ?

Not the answer you are looking for but I could not help it.

4. ### strantor Thread Starter AAC Fanatic!

Oct 3, 2010
4,325
2,008
http://my.bitscope.com/store/

5. ### GRNDPNDR Member

Mar 1, 2012
449
7
I don't know if it entirely meets your needs, and I'm also not very experienced in the area myself, but I just purchased and have used a TekTronix TDS1002b.

It can be connecte to a PC, but I don't know exactly what it does when connected because I haven't gotten into that yet.

It also has a USB slot for adding your own flash drive to record data, but again I don't know what it can record beyond a snapshot of the displayed waveform because I haven't tested that feature fully either.

There is also the TDS1012b which is higher bandwidth, and a TDS2024 but I don't know anything about that.

I know one of the models has detachable modules on the back for a printer, or cable connections etc.

The TDS1002b I was able to get for \$432 shipped, and lucky enough that it came from Toronto (I'm in London) but they usually sell on ebay for around \$500-\$1200

I'm not sure of the cost of the others. The big thing I really like about these scopes though, is that they are fairly portable because they're small in size and very light.

6. ### GRNDPNDR Member

Mar 1, 2012
449
7
just saw the bitscope thing..... I was way off lol.