2204A + Serial decoding CAN

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stefant
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2204A + Serial decoding CAN

Post by stefant » Thu Nov 14, 2019 5:11 pm

Dear reader,

I'm using a cheap 2204A to measure a 125kHz CAN bus signal. I also make use of the option Tools > Serial decoding > CAN, so that I can visualize the content of each message (ID + data). Please can you tell me if there is any way to measure continuously, let's say 10 seconds of data in one go, then have it analysed using the Serial decoding tool mentioned above?

Currently I'm using these options:
- Collection time: 2 ms/div
- Number of samples: 8 kS
which, if I understand correctly gives a discrete sampling frequency of 8kS / (2ms x 10 divisions) = 400 kHz. This means 400 kS recorded every second. Now, the Serial decoding tool is able to interpret messages, which is good.

What I have tried without success:
1. I have increased "Collection time" to 5ms/div: problem here is the Serial decoding tool is no longer able to decode the content..
1. Then I have increased the "Collection time" to 1MS, which translates to a sampling frequency of 1M/(5ms x 10 divisions) = 20 MHz, which honestly is impossible using a 10 MHz Picoscope. Result: Serial decoding tool still not able to decode the content..

Thank you.

Martyn
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Re: 2204A + Serial decoding CAN

Post by Martyn » Fri Nov 15, 2019 8:14 am

Try setting 1 S/div to and 10 MS and you will get streamed data of 10 MSamples across the 10 seconds on 1 single screen.
Martyn
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stefant
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Re: 2204A + Serial decoding CAN

Post by stefant » Fri Nov 15, 2019 3:28 pm

Hi Martyn,
Just tried that and it seems the sampling frequency of the recorded data is much lower than the expected 10 MS/ (1 sec x 10 divisions) = 1 MHz. Consequently the messages are missing bits of information and cannot be correctly decodified. I still cannot go higher than 2 ms/div for the "collection time". Any other ideas? Was there necessity of deep memory?

Martyn
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Re: 2204A + Serial decoding CAN

Post by Martyn » Fri Nov 15, 2019 4:41 pm

Go to Tools->Preferences->Sampling and make sure the slow sampling transition time is at the smallest value 100ms/div or 1 Second.

Then ensure that collection time is set to 1 Sec/div and then change the Collection Samples to 2GS so that it collects as many samples as possible, and turn off the decoder until you have collected a full buffer. When you start collecting the data it should draw slowly from left to right across the screen. This is streaming mode.
Martyn
Technical Support Manager

stefant
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Re: 2204A + Serial decoding CAN

Post by stefant » Fri Nov 15, 2019 7:10 pm

Dear Martyn,
It works. Thank you very much for your time.

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