| Products > Test Equipment |
| Using an oscilloscope for data acquisition |
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| Berni:
--- Quote from: nctnico on April 13, 2023, 02:17:01 pm ---@Berni: I think you need to read deeper into the origine of SCPI. Binary data isn’t a proprietary extrnsion. And it definitely is meant for realtime as well. Many A brand equipment even lists response and processing times for SCPI commands --- End quote --- Did go look at the SCPI specification here: https://www.ivifoundation.org/docs/scpi-99.pdf For binary data it specifies binary data as being ASCII encoded in binary,hex or octal. So they are sent as "#B00000011" or #"H03" or "#Q0003" But yeah the term SCPI tends to be used as a name for describing test equipment remote control, mostly because the majority of the equipment out there uses it for remote control. Perfectly fine to add proprietary commands on top since the SCPI spec cant possibly cover all use cases. It doesn't make SCPI impossible to use for high bandwith uses, just that the way it is typically implemented in test equipment does not lend itself to moving this much data this fast. Instruments that do need this much I/O performance tend to use other protocols that are purpusly built for it. --- Quote from: bifferos on April 13, 2023, 04:37:42 pm --- --- Quote from: jasonRF on April 13, 2023, 03:55:24 pm ---The OP needs at least 8 bits at 20 MS/s. Do you have any specific products that you could recommend for that sample rate? The least expensive picoscope that can do that seems to be the 2206b, which runs $419 US. It seems like there should be something available that is cheaper… --- End quote --- I really don't want a picoscope... for whatever price. I'm in the market for a new scope, could do with a 4-channel one, and don't really want to purchase hardware for a specific use that could just be left in a drawer unused. I don't really like PC scopes in general and prefer to have a bench-top one. The industrial ADC cards are really over-priced for what you get, and again, it's just going to sit in a drawer when I'm not using it whereas a new bench top scope will be something I'll be using all the time. If I wanted something custom I'd probably go the AD9226 route they have cheap boards on ali-express, but it's still a project to get the data into the PC, and that's not really the project I wanted! --- End quote --- Well you asked for scopes that can do this, and you got the answer. Id say 400 bucks is a pretty good deal. If i needed such a system and was to go cobble together one, i would likely spend more than 400 bucks worth of my time to get it working. Most people here agree that PC based scopes are annoying as heck to use. But they are the only kind of scope that actually benefits a good deal of functionality(long memory, analysis etc..) from having such a streaming mode, so for the designers of the scope it was worth the extra time and effort to implement the streaming functionality. For regular oscilloscopes that are designed to capture data at GS/s not MS/s they are architectured to process the samples locally at high speed, since this is too much data to stream to a PC anyway. Even things that do use SCPI control for running these scopes (like part of a industrial test system) will generally not have much use for it, they will typically just use automated measurements (like freqency, volts pp..etc) and grab the result over SCPI. If they do need the waveform, then they will typically set up the system to trigger on the exact required moment and only transfer the waveform of interest, since that is much faster than sifting trough gigabytes of data manually in software. Hence there is very little motivation for real oscilloscopes to have such a streaming feature in the first place. |
| 2N3055:
--- Quote from: PeDre on April 14, 2023, 10:58:15 am --- --- Quote from: Berni on April 14, 2023, 05:42:53 am ---Did go look at the SCPI specification here: https://www.ivifoundation.org/docs/scpi-99.pdf For binary data it specifies binary data as being ASCII encoded in binary,hex or octal. So they are sent as "#B00000011" or #"H03" or "#Q0003" --- End quote --- SCPI can use the IEEE 488.2 block format for binary data. This is also mentioned in the linked document. My instruments from Rigol or R&S also use the block format. Peter --- End quote --- Not in the one linked but this one...: DOI: 10.1109/IEEESTD.1992.114468 But that is support for the 8 bit integer and floating point binary BLOCK mode. There is no known implementation of STREAMING.. You could cache, block transfer, cache block transfer etc... But that requires even faster burst speed, and reassembly at target. There is no mention anywhere, streaming is supported for such high data volume device.... |
| zrq:
One may consider a Red Pitaya board. It's still overpriced given how poor their AFE design is and how cheap the Chinese scopes are today, but it should fit your need with a margin. |
| egonotto:
--- Quote from: zrq on April 14, 2023, 11:39:04 am ---One may consider a Red Pitaya board. It's still overpriced given how poor their AFE design is and how cheap the Chinese scopes are today, but it should fit your need with a margin. --- End quote --- Hello, with my Pitaya STEMlab 125-14 I reach max 14.897 MB/s with 1 channel and 8 Bit Best regards egonotto |
| zrq:
I haven't tried with my board yet, but the doc (https://redpitaya.readthedocs.io/en/latest/appsFeatures/applications/streaming/appStreaming.html ) say it can stream up to 20 MB/s via GbE. I know they are incompetent, but didn't expect this much... |
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