Products > Test Equipment

Pocket-Sized 6 GHz 1 TS/s ET Scope

<< < (61/107) > >>

joeqsmith:
The state machine looks for the unique response for each command.  It can't get out of sync, unless the scope starts sending the wrong acknowledges.   The software isn't yet self aware and can't modify its commands.  That's what I like about computers, they do exactly what you program them to, day in and out...

I do like protocols where every frame is processed the same.  Not where you have different end of frame markers and double CRLF in some cases.   Simple to me is making things consistent (and robust).   A goal of talking to the scope using a dumb terminal program seems of little value,  especially if it is making the system less robust, IMO. 

I saved the most recent responses and dumped them when this error happens.  Note the back to back calibrations prior to the D110000 fault.   It appears every time the scope receives two CAL commands, even though the state machine is waiting for them to send the OK CAL,  it seems to cause the fault.  Note that the first time I mention it, you can see the two CAL commands.   

I forced it to a single CAL command with no delays and it has not yet faulted out.   Are you only sending one CAL command or multiple?

***
It's been running for about 40 minutes now using a single CAL command and still no faults.   It is certainly a big clue into what is going on. 

SJL-Instruments:

--- Quote from: joeqsmith on February 11, 2024, 12:51:30 am ---I do like protocols where every frame is processed the same.  Not where you have different end of frame markers and double CRLF in some cases.   Simple to me is making things consistent (and robust).   A goal of talking to the scope using a dumb terminal program seems of little value,  especially if it is making the system less robust, IMO. 

--- End quote ---
This does make sense. The intention was to have a simple single-CRLF response whenever possible. This doesn't work for binary data, and so is the one exception. The double CRLF was unintentional, since the delay underflow warning is intended to never happen in normal operation.


--- Quote from: joeqsmith on February 11, 2024, 12:51:30 am ---I saved the most recent responses and dumped them when this error happens.  Note the back to back calibrations prior to the D110000 fault.   It appears every time the scope receives two CAL commands, even though the state machine is waiting for them to send the OK CAL,  it seems to cause the fault.  Note that the first time I mention it, you can see the two CAL commands.   

I forced it to a single CAL command with no delays and it has not yet faulted out.   Are you only sending one CAL command or multiple?

***
It's been running for about 40 minutes now using a single CAL command and still no faults.   It is certainly a big clue into what is going on. 

--- End quote ---
This is very interesting, and puzzling. We still can't reproduce this behavior - issuing an arbitrary number of CAL commands, then a D command, works every time on our test units. It also doesn't explain why adding a 30 ms delay seems to avoid the problem.
That said, the way the official software is set up, it happens to issue at least one other command in between every two CAL commands.

***

We're running stress-tests where we send a random sequence of CAL and D commands (with random parameters) with no extra delays. So far, everything is working as intended..

***

After carefully checking the relevant code path in the firmware, the only way a "Delay underflow -inf" message can occur is if the parameter passed to the D command is below 20000 (2 ns). This is regardless of what the CAL command does, even if the calibration result is completely wrong.
Of course, we're sure this isn't what you intended to do - the problem could lie on either the scope side or the LabView side, but it's definitely a serial issue.

If you'd like, we can send you a firmware patch which returns more information when this warning is issued. It could help clarify what is happening.

joeqsmith:
Serial communications have been in use long before I started my career.  I wouldn't have thought there was much of a point in reinventing the wheel.  I don't see using your company name as an end of frame marker as being professional.   Again, just MO.  I don't like having to deal with these special fringe cases that fall outside of what is considered normal.   Its not a productive conversation to be having as it sounds like there is no chance in changing it.  I will drop it and work around what you have. 

My setup has been running for about two hours without a warning after removing back-to-back calibrations.   It appears to solve what ever the problem is.  So does adding a small delay after the second CAL.   It's odd you are unable to replicate it.   My code performs error checking and re-transmission already and I will also change it to make sure your scope never sees back to back calibration commands.  Basically my plan forward is to bury the problem as I am not sure what else I can offer you to help in this matter.   Just be aware something odd is happening with calibrations and setting the delay, and not understanding it may come back to haunt you in the future.   :-DD 

This scope has been in pretty much non-stop use since I had reworked the board and while there could still be something abnormal with this unit, I have not seen any other strange behaviors outside of what I have mentioned here.  It now appears to be very solid.   But maybe there is something else going on with part variances (FPGA) that effects the design.   Time will tell as you build more units. 

SJL-Instruments:

--- Quote from: joeqsmith on February 11, 2024, 03:01:01 am ---Serial communications have been in use long before I started my career.  I wouldn't have thought there was much of a point in reinventing the wheel.  I don't see using your company name as an end of frame marker as being professional.   Again, just MO.  I don't like having to deal with these special fringe cases that fall outside of what is considered normal.   Its not a productive conversation to be having as it sounds like there is no chance in changing it.  I will drop it and work around what you have. 

--- End quote ---
Given the interface we have already defined, there is still enough leeway to implement an SCPI interface without breaking backwards compatibility. This will not come out before your review is published. You should review the product as it exists now. But this is just to say that we understand your point, and want to do better.
We will later release an SCPI-compatible firmware update, and any future product we launch will have an SCPI interface by default.


--- Quote from: joeqsmith on February 11, 2024, 03:01:01 am ---This scope has been in pretty much non-stop use since I had reworked the board and while there could still be something abnormal with this unit, I have not seen any other strange behaviors outside of what I have mentioned here.  It now appears to be very solid.   But maybe there is something else going on with part variances (FPGA) that effects the design.   Time will tell as you build more units. 

--- End quote ---
Thanks again for the careful testing you've done. We haven't received any other reports of hardware issues outside of the the ones you've mentioned. For now, we are confident that the "growing pains" have been resolved, and the hardware is stable.


--- Quote from: joeqsmith on February 11, 2024, 03:01:01 am ---My setup has been running for about two hours without a warning after removing back-to-back calibrations.   It appears to solve what ever the problem is.  So does adding a small delay after the second CAL.   It's odd you are unable to replicate it.   My code performs error checking and re-transmission already and I will also change it to make sure your scope never sees back to back calibration commands.  Basically my plan forward is to bury the problem as I am not sure what else I can offer you to help in this matter.   Just be aware something odd is happening with calibrations and setting the delay, and not understanding it may come back to haunt you in the future.   :-DD 

--- End quote ---
As a precaution, we have added a note about repeated CAL commands in the next manual revision. The official software happens to be set up in a way that never sends back-to-back calibrations, and so avoids the issue. Thanks for bringing it to our attention.

joeqsmith:
I let it continue to run without the back-to-back CAL and saw no problems.   I have gone ahead and made these changes to my software.   To be clear,  I have no plans to write an interface for your scope, but at least now I have what I consider a good platform to build on if I need it.   
 

--- Quote from: SJL-Instruments on February 11, 2024, 04:32:52 am ---This will not come out before your review is published. You should review the product as it exists now. But this is just to say that we understand your point, and want to do better.
--- End quote ---

For the review, I had planned to only show your software.  So these details about your choice for the serial interface are not relative.  I have thought about doing a segment on my LabView source code.  With it being pretty much a dead end tool now with their extortion tactics and subscription model  there may not be any value in including it.  Someone wrote me the other day who had attempting to reinstall their older version of LabView and claimed they could not get their license to authenticate.  That's twice now I have heard that.  One was from a university.   

Some parts of my review that I had already recorded will need to be updated.   For example I had done a tear down at the time I reprogrammed the unit.  Because I had not removed the PCB from the case, you only got to see the top side.   When I reworked the board, I did not record anything.  The focus wasn't about making a video but rather attempting to solve the random problems I was seeing.  Working with these tiny parts gets more difficult as I age and the risk of damaging the unit because of not being focused on the task at hand was too great.   Now, with the new case coming, I will redo this section of the review.  Pretty sure I can swap out the case on video and not damage the scope.   :-DD  Other parts of the video where I was limited by your software may also change.   

Honestly, had I just reviewed the scope the way it stood when it arrived, it wouldn't have presented itself well.  Over the last month, things have really started to shape up.  I would like that power user mode but can certainly proceed without it.   

Making reviews isn't really something I am good at to start with.  Compound that with the moving target you have provided, it adds an extra layer of difficulty.  If it were a simple unbox, look at the parts supplied, five stars... Maybe include some music and talk about what an expert I am, then sure, I can have it done today.   I suggest you be patient.     


--- Quote ---Thanks again for the careful testing you've done. We haven't received any other reports of hardware issues outside of the the ones you've mentioned. For now, we are confident that the "growing pains" have been resolved, and the hardware is stable.

--- End quote ---


I too am confident in the the hardware design.  Your build quality is still a question as I have not seen what your production process looks like.  The firmware/software seems a bit lacking but as you have said, you plan to continue to develop it.  Potential customers just need to be aware that any limitations I may show during the review could possibly be addressed in the the future.  Of course, no guarantees. 
 

--- Quote --- As a precaution, we have added a note about repeated CAL commands in the next manual revision. The official software happens to be set up in a way that never sends back-to-back calibrations, and so avoids the issue. Thanks for bringing it to our attention.

--- End quote ---

If you can't replicate it, and nothing in your design appears to match up with the symptoms I have described, I really don't know what else you can do at this point. 

***
grammar 

Navigation

[0] Message Index

[#] Next page

[*] Previous page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod