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PicoScope 2200 Continuous Sample Rate

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PicoScope 2200 Continuous Sample Rate

Postby Brehministrator » Sat Nov 15, 2014 3:07 pm

I am planning to buy a USB scope and have a few questions:

In the PicoScope 2200 product description it is stated that the "small" scopes (2204A and 2205A) have a continuous streaming sample rate of up to 1 MS/s, whereas the larger models (2206A, etc.) have 9.6 MS/s. However, in several places it is written that the PicoScope 6 software does not support continuous streaming faster than 1 MS/s. If this is true, what would be the use of having a device which is able to stream samples at the higher rate, if the software does not permit this?

Another question: These scopes allow decoding and logging of serial communication (e.g., I2C bus). Is it possible to continuously log data packets on the bus (in continuous streaming mode), or can this only be done in short time intervals? My application requires continuous logging within around 60 seconds (at, let's say, 5 MS/s) to make sure all packets have been captured.
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Re: PicoScope 2200 Continuous Sample Rate

Postby Hitesh » Mon Nov 17, 2014 3:31 pm

Hi Brehministrator,

The PicoScope 6 software will allow up to a maximum 10MS/s (shared between all channels) in streaming mode, apart from the PicoScope 2104/5, 2204A and 2205A as they are low memory devices.

With the deeper memory devices e.g. from the PicoScope 3000 Series, it is possible to achieve faster streaming rates when using the Software Development Kit.

e.g. the USB 2.0 PicoScope 3206B should be able to achieve ~30MS/s while the new USB 3.0 PicoScope 3200 and 3400 D MSO models are capable of around 125MS/s (shared between all channels and dependent on PC resources).

If you are referring to the 'Using PicoScope PC Oscilloscopes for Fast USB Data Acquisition' article (available from http://www.picotech.com/support/kb/kbfiles/PicoScopeUSBStreaming.pdf) with respect to the quoted 1MS/s, then it is scheduled for an update by our Technical Publications team in light of the new products.

With regards to serial decoding, the data would be processed post-capture, so you could collect the data and then view the packets once they have been decoded afterwards. The data cannot be processed in the midst of collection, but it can be processed once a trace has been collected.

I hope this helps.

Regards,
Hitesh

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Re: PicoScope 2200 Continuous Sample Rate

Postby Brehministrator » Mon Nov 17, 2014 4:09 pm

Hi Hitesh,

thank you for your reply, this clarifies most of my questions.

To be sure: If I would buy a PicoScope2206A, I would be able to capture and stream data at 9.6 MS/s for as long as I want (only limited by the hard disk capacity of my computer)? And afterwards, I can perform a serial decoding on all the recorded and stored data, therefore obtaining a complete log of packets which were transmitted during the capture time? Even if the capture time is quite long (e.g., 60 sec. at 10 MS/s corresponds to 600 millions of samples...)?

My computer has a fast SSD drive as well as fast CPU and large RAM, those will not limit the process.

This would be exactly what is required for my project :D
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Re: PicoScope 2200 Continuous Sample Rate

Postby Hitesh » Tue Nov 18, 2014 12:01 pm

Hi,

The PicoScope 6 software has a limit for the record length of 100MS when collecting data in streaming mode, so you would only be able to collect this quantity of data and then would have to save the data to disk, before starting a data capture.

Furthermore it is not possible to collect data using PicoScope 6 at 9.6MS/s over 50 (5s/div) or 100 (10s/div) seconds.

To collect data that is only limited by the size of the hard disk, you would have to use the Software Development Kit, but this does not provide the ability to perform serial decoding on the data collected - you would have to implement your own algorithm.

What is the time interval between packets as you might be able to use block mode using a PicoScope model with deep memory.

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Hitesh

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Re: PicoScope 2200 Continuous Sample Rate

Postby Brehministrator » Tue Nov 18, 2014 3:11 pm

Hi,

Ok, the 100 MS limit corresponds to 20 seconds at 5 MS/s, this will probably be enough for my application. Does this 100 MS limit apply to each channel, or to the sum of both channels? In other words: Will I be able to capture two channels for 20 seconds at 5 MS/s (corresponding to 100 MS per channel), or will this be possible only for 10 seconds (corresponding to 100 MS in total)?

Is there an important reason for this 100 MS limit? Modern workstations have almost unlimited RAM and hard disk ressources, so I do not completely understand why this limit exists. Probably it can be lifted in a future release of the PicoScope software.
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Re: PicoScope 2200 Continuous Sample Rate

Postby Hitesh » Tue Nov 18, 2014 4:26 pm

Hi Brehministrator,

The 100MS record is shared between channels so with 2 channels, you can capture a maximum of 50MS per channel.

There limit is there in order to preserve PC resources as the data is collected into PC memory rather than being written to file as it is being collected. PicoScope 6 is a 32-bit application, so there will be a limit in terms of addressing memory space.

A feature request has previously been made to the Development Team and I will add your comments to this for future consideration.

I hope this helps.
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Re: PicoScope 2200 Continuous Sample Rate

Postby Brehministrator » Tue Nov 18, 2014 6:48 pm

Hi Hitesh,

thanks for the explanations and the detailed information. After considering all those points, I think the PicoScope 2200 series will match my requirements. So your company just got a new customer :)

Regards,
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Re: PicoScope 2200 Continuous Sample Rate

Postby Hitesh » Wed Nov 19, 2014 9:31 am

Hi Brehministrator,

Excellent! :D

Hope your new PicoScope serves you well.

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