Is a 'draw' mode possible

Forum for discussing PicoScope version 6 (non-automotive version)
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JamesW
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Is a 'draw' mode possible

Post by JamesW » Mon Mar 19, 2018 9:18 pm

Hi, I have been using my Pico 2204A at work for a while now (I work in an Audi dealer). I like the reliability of the scope and the portability of it compared to the supplied scopes on our diagnostic machines (an AVL unit VAS 6356). I also like the functionality the Pico 6 software offers, for such entry level hardware it's great. There is one function I miss from the scopes on our diagnostic machines though which I do not seem to be able to reproduce on the Pico, that function is 'draw' mode. Basically the function allows for a constantly moving trace from the right of the screen to the left which can be recorded as a long term measurement for up to 24 hours to analyse a long term parasitic current drain for example, then condense the data on to one full trace once the measurement is stopped (I guess in a kind of data log fashion). It makes it easier to spot changes in current draw being able to always see the previous few seconds rather than a having page that keeps getting overwritten. This also works well when checking slower changing sensors such as NTC temp sensors etc.

I also use this feature with a much shorter time per division to capture outputs to audio speakers, as it helps to see the voltage trace as the audio waveform would look in an digital audio workstation editing software, helping to eliminate poor sounding speakers from amplifier problems. Is this a feature that is possible in the Pico 6 software or something that could be introduced? I have a video of a trace from our diagnostic machine if this helps to explain my question.

Thanks, James

phils
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Re: Is a 'draw' mode possible

Post by phils » Tue Mar 20, 2018 10:04 am

Hi James

First - thanks for your purchase of a PicoScope 2204A; it is a great scope for general electronics work and extremely portable.

As Martyn has already replied, it is really not recommended for automotive workshop use. Please also see Steve Smith's great automotive forum post on this issue:
https://www.picoauto.com/support/post87 ... 000#p87821

I also include below a summary comparison between the 2204A and the 4225/4425 scopes:

Comparing the resolution of the two scopes is a bit like comparing an old monochrome TV with a 4K display.
The 2204A is fine for digital signals, and low-resolution analog signals; but the additional ranges, resolution and protection on the 4225 were designed to suit automotive diagnostics.

When it comes to CAN decoding, you want a sample rate of at least 10MS/s; at this rate you have 10K samples just for one and a bit messages. The 2204A has only 8k samples total buffer (so 4k samples per channel if capturing CAN Hi and CAN Lo), so you have to drop the sample rate just to capture one message. FlexRay is obviously completely beyond the 2204A.

Apart from all the automotive features such as the waveform library and guided tests, the ability to diagnose transmission, suspension, engine and other NVH (Noise Vibration & Harshness) problems with the automotive scope is another great benefit of using the 4425 or 4225.

Best regards
Phil (Automotive)
Attachments
2204A comparison.png
2204A vs 4225 comparison

JamesW
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Re: Is a 'draw' mode possible

Post by JamesW » Tue Mar 20, 2018 8:31 pm

Hi Phil, thanks for the reply and all the detail regarding the spec comparisons and uses. I have been keeping the 2204A well within its limits, I am aware it is really not designed for the automotive environment. As I said in the reply to Martyn, I find it really useful for specific applications such as drop outs from loose terminals on interior functions when road testing (using the persistence mode). I think the 2204A is generally a great introduction to the Pico 6 software to get an idea of the software/hardware combination ability.

The automotive scope would definitely open up a whole lot more uses for the scope, I just need to convince the company to buy one! Is the automotive scope fast enough to decode the latest ethernet networks too?

Kind regards, James

Martyn
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Re: Is a 'draw' mode possible

Post by Martyn » Thu Mar 22, 2018 11:07 am

For draw mode there are two possible options for you that may provide you with the required information :-

Select a long timebase, the software can go up to 14 hours for most scopes (5000s/div), and then use the zoom tools to look in detail at the trace.

Set a trigger point that is positioned at the top right hand edge of the screen, and at a level the signal never reaches. The scope will now draw to the right hand edge and scroll the data left, although as soon as data leaves the left hand edge it will be lost.
Martyn
Technical Support Manager

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