Author Topic: DS1054Z decode timebase problem  (Read 3302 times)

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Offline MattSR

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DS1054Z decode timebase problem
« on: April 07, 2015, 10:47:19 AM »
Hi all,

I have a DS1054Z scope with the RS232 Serial decode option. The decoder works fine, however the decoder automatically disables itself when the timebase exceeds 100ms.

Is this normal? Is anyone experiencing similar limitations on this or other decoders?


Cheers
Matt


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Offline LA7SJA

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Re: DS1054Z decode timebase problem
« Reply #1 on: April 08, 2015, 12:46:50 AM »
If you are in DataSrc=trace then this could be correct, but I don't have a DS1054Z in my homelab (yet) to try out.

Do you know the sample rate and the DataSrc settings?
This is from page 7-4 and 7-5 in the (l)user manual.

Quote
Press Width to turn the width display function on or off. When it s turned on, the current bus width will be displayed on the right of the format display (when the bus display is turned on), and you can use Width to set the bus width.
Press DataSrc to select “Trace” or “Memory” as the data source.
Dig. Sa displays the current digital sample rate. The digital sample rate is related to the data source currently selected. When  the data source is set to “Trace”, the digital sample rate is related to the horizontal time base; when the data source is set to “Memory”, the digital sample rate is related to the sample rate and memory depth.
This is not so clear but you should try the different setings.

Johan-Fredrik
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Offline electr_peter

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Re: DS1054Z decode timebase problem
« Reply #2 on: April 08, 2015, 01:02:13 AM »
I have a DS1054Z scope with the RS232 Serial decode option. The decoder works fine, however the decoder automatically disables itself when the timebase exceeds 100ms.
Is this normal? Is anyone experiencing similar limitations on this or other decoders?
How does the signal look good on display to you (is it decodable just by looking at it)? The problem may be that DS1054Z decodes from the screen only ("Trace"), you cannot choose "Decode from memory". Decode from memory is not implemented (see other threads about this issue).
If signal is incomplete on the screen due to timebase, decoding will fail - decoder only sees what is on the screen.
« Last Edit: April 08, 2015, 01:06:00 AM by electr_peter »
 

Offline kwass

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Re: DS1054Z decode timebase problem
« Reply #3 on: April 08, 2015, 01:13:48 AM »
If you are in DataSrc=trace then this could be correct, but I don't have a DS1054Z in my homelab (yet) to try out.

Do you know the sample rate and the DataSrc settings?
This is from page 7-4 and 7-5 in the (l)user manual.


The older version of the manual does indeed say that, but not the current version.  In fact, the option to select DataSrc=memory is not implemented on the DS1000z series.

I can confirm that the behavior that you noticed on RS232 decode with time base settings more than 100ms/div is normal.  Screen memory is clearly quite limited so the only reason for serial decode to work with such a long time base would be if you had a ridiculously slow baud rate.  The lowest baud rate that the scope will accept is 110 baud (enter 1 baud and it will set it to 110 baud).  At 100ms/div that works out to roughly 10 transitions per division.
-katie
 

Offline milow

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Re: DS1054Z decode timebase problem
« Reply #4 on: April 09, 2015, 06:55:12 AM »
I wonder what the reason for these restrictions are. Why is the digital sampling rate of the Decoder so tightly coupled to the timebase? Why can it only what's on the screen? If there would be no such restrictions I would't hesitate to buy it, but right now I have to think twice.

It seems like this is an arbitrary restriction to sell the more expensive products where I guess it's possible.

Is it possible to decode when segmented memory is used?
 

Offline dadler

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Re: DS1054Z decode timebase problem
« Reply #5 on: April 09, 2015, 07:36:17 AM »
I know the DS2072a now supports decoding from segmented memory, since a firmware update last year. I have not tried it on the DS1054z.
 

Offline Phil_L

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Re: DS1054Z decode timebase problem
« Reply #6 on: April 09, 2015, 08:24:43 AM »
If you use the event table it'll still decode even when it doesn't display the values on trace. It is still limited but much more usable than the on-screen decoder.
 


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