Rigol DHO800/900 Oscilloscope Bug Reports + Firmware

[Fungus]

Just checking: You do have your probe attenuation set to 1x on the 'scope, right?

No. 10x on the probes, 10x on the probe settings. Is there some reason why I shouldn't be doing that for decoding?

It's a well-known bug in the decoders. You need to set 1x attenuation on the 'scope or the decoder threshold voltage is wrong (10x too small).

(keep the switch at 10x on the probes, obviously)

[Howardlong]

It's a well-known bug in the decoders. You need to set 1x attenuation on the 'scope or the decoder threshold voltage is wrong (10x too small).

I can't tell if you're joking or not?

[csuhi17]

I ran several test with the threshold voltage and found that it is the threshold voltage scale issue. If I set the probe to X1 scale then everything works fine but with the X10 probe scale does not work because  the actual threshold voltage 10 times less than I set. But if I increase the threshold voltage 10 times (10V instead of 1V) then decoding starts again.

Yep. I received my 'scope today and serial decoding only works when the probes are set to 1x.

Edit: This is NOT fixed in the 1.01 firmware.

...

[Fungus]

It's a well-known bug in the decoders. You need to set 1x attenuation on the 'scope or the decoder threshold voltage is wrong (10x too small).

I can't tell if you're joking or not?

This bug has been discussed many times here... 

It's been on the bug list since at least November:
https://www.eevblog.com/forum/testgear/another-bug-in-the-rigol-dho914sdho924s-bode-plot-feature/msg5184534/#msg5184534

Edit: This is NOT fixed in the 1.01 firmware.

It's supposedly fixed in the DHO1000 since a few weeks ago.

(last item in the changelog)

https://www.eevblog.com/forum/testgear/new-rigol-hdo1000-12-bit-dso-bugs/msg5553587/#msg5553587

[Howardlong]

It's a well-known bug in the decoders. You need to set 1x attenuation on the 'scope or the decoder threshold voltage is wrong (10x too small).

I can't tell if you're joking or not?

This bug has been discussed many times here... 

It's been on the bug list since at least November:

I honestly don't know what to say, other than to reiterate that this scope is an ornament, and it will remain so until the firmware comes out of alpha.

I'd already run out of patience with this scope half a dozen times before, with rose tinted glasses thinking it can't be that bad. Every time it's been a disappointment.

No one should be considering purchasing this scope with its current firmware state, unless they like adorning their bench with ornaments.

[rpro]

It's a well-known bug in the decoders. You need to set 1x attenuation on the 'scope or the decoder threshold voltage is wrong (10x too small).

I just tried it with the Batronix demo board and 10x on probes and scope are working fine with I2C (DHO800).

[Fungus]

It's a well-known bug in the decoders. You need to set 1x attenuation on the 'scope or the decoder threshold voltage is wrong (10x too small).

I just tried it with the Batronix demo board and 10x on probes and scope are working fine with I2C (DHO800).

It can work on 10x but your signal has to go all the way to zero.

If there's even a tiny offset (eg. 0.2V) due to probing or whatever then you can get caught out by this bug.

Setting probe to 1x makes sure.

[Fungus]

It's been on the bug list since at least November:

I honestly don't know what to say

It was literally being discussed in the post you originally quoted.

That's why I said:

Just checking: You do have your probe attenuation set to 1x on the 'scope, right?

nb. I'm not name-calling, we all miss stuff, but this bug has been discussed endlessly here.

[Howardlong]

It's been on the bug list since at least November:

I honestly don't know what to say

It was literally being discussed in the post you originally quoted.

That's why I said:

Just checking: You do have your probe attenuation set to 1x on the 'scope, right?

nb. I'm not name-calling, we all miss stuff, but this bug has been discussed endlessly here.

As I already stated, I've already wasted enough time on this scope and its litany of bugs. When there's a new firmware release I'll revisit.

Until that time, anyone considering purchasing a scope should avoid this one.

[Lathe26]

Multiple bugs / limitations that make it hard to save / export Logic Analyzer data, at least with the v01.02.00.02 firmware:

• WFM file format only supports saving analog data.  It doesn't save digital data from the LA, even though the UI makes appear this is possible.  This was uncovered while decompiling the libscope-auklet.so file while reverse-engineering the WFM file format.  Unclear whether this is a bug or limitation of the file format.
• BIN file format supports saving digital data and analog data.  However, due to a bug, BIN files can only be successfully saved if both the LA and a CH are active.  If only the LA is on, then the BIN file's header will be written but LA data is missing.  On the upside, the BIN file format is well documented in the DHO800/900 User Guide PDF.
• CSV file format supports saving digital-only, analog-only, and digital+analog.  The file format is easy to read.  The only downside is the large file size and how slow large samples takes to write to disk.
• SCPI support for retrieving digital data is broken.  Setting the source to a D0 thru D15 channel fails (e.g., ":WAVeform:SOURce D0").  The scope displays "Remote Cmd Execute Error" on its screen.  Querying ":SYSTem:ERRor?" often returns "-200,"Command execute failed" and querying ":WAVeform:SOURce?" always returns the previous setting.

Anybody know of work-arounds or additional ways to save / export LA data?

[joe500]

Hello community! Im Happy with my DHO914s so far. But when I tried to decode a simple spi message the scope would not show anything. I've set Mosi, CLK and CS. I've the open source digital interface. As can be seen in the picture the spi message gets picked up perfect but no decoding is happening. Is this a bug or am I missing out on something?

[Howardlong]

Hello community! Im Happy with my DHO914s so far. But when I tried to decode a simple spi message the scope would not show anything. I've set Mosi, CLK and CS. I've the open source digital interface. As can be seen in the picture the spi message gets picked up perfect but no decoding is happening. Is this a bug or am I missing out on something?

SPI decode doesn't work on the LA channels. See post #124. It's a bug that's never been addressed in any public firmware release.

[TomKatt]

SPI decode doesn't work on the LA channels. See post #124. It's a bug that's never been addressed in any public firmware release.

Seems like decoding LA channels would have been basic QA testing?  And not only did that bug get through testing, but is still unresolved?  Sometimes it feels like the VESA mount got more attention than the firmware…

[joe500]

SPI decode doesn't work on the LA channels. See post #124. It's a bug that's never been addressed in any public firmware release.

That's a real bummer  . But thank you for the clarification 

[Howardlong]

That's a real bummer

Not least because this exact use case is exceptionally common on an MSO, leaving the analogue channels available to probe around other time-correlated stuff.

[Aleksandr]

By the way, here is an example of work I2C. And it works somehow.

[Howardlong]

By the way, here is an example of work I2C. And it works somehow.

Yes, I2C does work on the LA.

For SPI, there is a lot wrong with the decoder dialogue box with the LA such as it asks for things like threshold voltages on LA channels. It's likely that feeds into the issue where it appears just not to work.

The SPI LA issue alone means it stays in the cupboard.

Disappointing is that there's no evidence Rigol are interested in fixing this, or a multiplicity of other issues that show themselves within an hour or two of using it.

The MSO5000 I sometimes have on the bench is, apart from a few relatively minor irritations that I can bear with, far better in comparison. (Although I had a repeating issue with a regulator blowing on the main board, covered elsewhere: I now have a replacement unit now with a 3 year guarantee).