Re: [Linux-gpib-general] Help needed

[Adrian S. <ben...@gm...>]

Hi all,

I would like to thank Dave P. and Paul G. for their suggestions. I think we
all agree that all in all it is easier to read the data and plot it with
gnuplot or something else but I wanted to have the second option suggested
by Dave for the sake of completeness. Following Dave's suggestion I did the
following:

   - looked around through examples folder in linux-gpib-user-4.3.0 and
   found slave_read_to_file.c
   - configured the 70206A to plot on a listen only plotter
   - used the slave_read_to_file binary to capture the output to a file
   - issued plot command on the device

While that seemed to have worked and I managed to get valid PLT content,
this approach has some problems which I hope you can help me with:

   1. I cannot seem to reliably start the listener in order to capture the
   plotting content. I only managed once and I'm not sure as to what I did to
   make it work. Currently I start the same program (slave_read_to_file) and
   issue a PLOT command on the SA but nothing happens; the slave does not
   capture anything and the device remains in a blocked state.
   2. The slave_read_to_file uses ibrdf(). I looked into the source code
   and it seems that ibrdf() uses a buffer of 0x4000 bytes. This causes
   content to only be written to the file in 16KB chunks, so I get incomplete
   PLT content in the file whenever the plot size is not aligned to a 16KB
   boundary. One idea would be to be able to read one byte at a time and track
   the output and stop whenever the plot finishes.

How would you suggest I tackle these problems? I am a programmer by trade
so I'm not afraid to get my hands dirty with code. I'm mostly interested in
solving the 1st problem. Is there a way I can debug things? What is the
expected sequence of events in this particular setup?

Thank you very much,
Adrian

On Thu, Dec 19, 2019 at 7:27 PM dave penkler <dpe...@gm...> wrote:

> Generally it is easier to read the data and then use something like
> gnuplot to plot it. It is possible to plot to the card by sending the
> appropriate low level set talker and listener commands and then initiating
> the plot from the instrument while reading the plot output
> programmatically.
> cheers,
> -Dave
>
>
> On Thu, 19 Dec 2019, 18:01 Adrian Scripcă, <ben...@gm...> wrote:
>
>> Hello all,
>>
>> I am just getting started with linux-gpib and gpib in general and I would
>> require some guidance from more knowledgeable members.
>>
>> Context: I have some HP equipment (HP8656B and a 70000 series SA) which I
>> am trying to communicate with and an Agilent 82357B adapter bought from
>> eBay (most likely a clone but should do).
>>
>> I run a Ubuntu 19.10 distribution with 5.3.0-24-generic kernel so I
>> installed linux-gpib-4.3.0 first. Installation went painlessly. I finally
>> managed to connect to the equipment and issue commands, modifying and
>> querying the state.
>>
>> The next step however is to see whether I can obtain plot data from the
>> spectrum analyzer. So here goes my question: is there a way in which I can
>> emulate a listener with a given address on the GPIB bus and read data while
>> also being connected to the SA and issue commands to it?
>>
>> Sorry if my questions sound confusing but as I mentioned before this is
>> my first interaction with linux-gpib and gpib in general.
>>
>> Thank you,
>> Adrian
>>
>>
>>
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>