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Spoll/Serial Polling Alignments completed

Question asked by batigol

on Jun 6, 2018
Latest reply on Jun 11, 2018 by MikeM

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Hi,

I have spent already considerable time with the Keysight Literature and below VEE example but I still do not get how to manage the sync with the SA while the full alignments are being run.

How do I poll to determine when the internal alignments are complete on my X-Series or PSA Series Signal Analyzer | Keys…

As soon as I send the CAL:ALL command to my SA, the box will not react to any other sequential commands as long as the Alignments are running. Depending on the box, this may demand some minutes.

One "dirty" way of doing this, is to increase the time out of the interface accordingly before sending CAL:ALL.

In this way, I can send afterwards a sequential command such as OPC? to monitor the end of the Alignments.

But this requires to know in advance how long my Alignments will take, so that I can set up the time out upfront.

Other two possibilities are to set an interrupt method or to serial poll the status byte.

After having run several tests and having read quite a lot, I am not able to understand how to implement the second method which is normally described everywhere as spoll.

Could somebody help?

Thx

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MikeM Jun 6, 2018 1:36 PM
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You're right, once you send the calibration command the instrument will not respond to any other command, but it will respond to a serial poll. I have used the serial poll just as the example shows in VEE, but I usually do it another way.

What I do is shorten the timeout then send the :CALL:ALL? query. I then have a loop that queries the response with an error bailout that will go to next for the loop when it times out. It goes through the loop until it finally responds. I then reset the timeout and move on.

This way you don't have to try to figure out ahead of time how long it will take. It will return a 1 or 0 with the status of the calibration when it's done. I also sometimes set a timer or counter in the loop for something beyond what I think it should take so that if it doesn't come back I won't be stuck in the loop forever.

Also, have you tried the :CAL:EXPIRED? query?

Regards,
Mike
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- batigol @ MikeM on Jun 7, 2018 4:19 AM
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  Hi MikeM,
  
  Thx for the reply, first of below again the link to the VEE example where the end of CAL:ALL is being checked with serial polling.
  https://www.keysight.com/main/editorial.jspx?cc=DE&lc=ger&ckey=2332063&nid=-32408.752542.02&id=2332063
  I believe the link did not came properly in my initial post. I got this example to run but the IO Monitor just does not show which are the SCPI commands I need to run the serial polling.
  Going back to your proposal, see below my comments,
  Do you happen to have a C example for this? I am trying to implement this with Visual Studio C/C++
  From my tests I saw that before sending CAL:ALL and assuming the Alignments take some minutes, you need to increase the default time out accordingly. Otherwise there will be a time out error. For example see below sequence I run on one N9020B, the alignments there take more a less 2 minutes. Therefore I set the timeout to 3 minutes right before calling CAL:ALL.
  After this command I set up strategically another sequential command to change the center frequency. As long as CAL:ALL is running, Command Expert will not send the last command.
  
  :SENSe:FREQuency:CENTer 10000000
  (SET DefaultTimeout to 180000)
  :CALibration:ALL
  :SENSe:FREQuency:CENTer 100000000
  
  Wouldn’t this also apply to CAL:ALL? At the end this is also a sequential command.
  This would mean for me that as long as CAL:ALL is running, you may query several times with CAL:ALL?; but this will give you several time outs as long as the full Alignments is still running.
  
  Hope I am not missing something.
  
  There is actually one online example which claims it implements serial polling during CAL:ALL is running. But this seems wrong to me, at the end the program is doing following,
  -increasing time out till 60 sec
  -sending CAL:ALL
  -querying with ESR every second to monitor the end, I tested this and this generates a time out every second. This makes sense since ESR is a sequential command and the box will not react till CAL:ALL is done.
  https://www.keysight.com/upload/cmc_upload/All/SerAlign.c
  
  It seems to me as the serial polling setting depends on the interface being used, I found below statement in our X Series SCPI ref guide,
  “Finally, you would use the serial polling functionality available for the particular bus/software that you are using to monitor the Status Byte Register.”
  
  The question would be how to do this within Visual Studio, a normal programming environment for our customers out there.
  
  By the way I tried CAL:EXP?, but this is also tricky since the command is a query and it generates alignments also itself.
  Therefore if you send it and too many alignments will be run, you ll get a time out as well. And it is difficult to know how many alignments have expired upfront to set the time out accordingly.
  
  Let me know your thoughts.
  
  Cheers
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  - batigol @ batigol on Jun 10, 2018 8:09 AM
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    Hi,
    
    I managed to run a matlab programm which polls successfully the end of CAL:ALL via serial polling, the code looks pretty much as below,
    
    % Commands
    fprintf(N9020B, '*CLS');
    fprintf(N9020B, sprintf('*ESE %d', 1));
    fprintf(N9020B, ':CALibration:ALL');
    fprintf(N9020B, '*OPC');
    
    i=0;
    while i==0
       [out1 statusbyte] = spoll(N9020B)
       if statusbyte == 32
           i=1;
       end
    
    This follows the same guidelines as Keysight online VEE Cal:All example I quoted before,
    How do I poll to determine when the internal alignments are complete on my X-Series or PSA Series Signal Analyzer | Keys…
    
    I found the serial polling Matlab command in below link,
    Perform serial poll on VISA objects - MATLAB spoll (visa)- MathWorks Deutschland
    
    If someone knows how to implement the serial polling with C++, I d be grateful to see the info.
    This is the one thing I still could not find about around this subject.
    
    Cheers
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  - MikeM @ batigol on Jun 11, 2018 12:12 PM
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    Check out the examples at: http://www.keysight.com/find/sa_programming I think you will find a serial poll example in C++ there.
    
    When I say I shorten the timeout I do this along with trapping the timeout, which I expect to happen. I set the timeout to a shorter value so that it will not hold up the program as long until it tries again. While it hasn't completed the calibration it will continue in a loop until it does. My VEE program looks something like this:
    As you see, VEE allows me to do something other than hang up when the IO times out by using the Error output. This allows me to control the flow of the program even though the instrument will not respond until the calibration is done, without crashing the program.
    
    Regards,
    Mike
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