Experimental Physics and
Industrial Control System

Rod Nussbaumer <[email protected]> · Fri, 04 May 2012 07:23:01 -0700

Pavel:

We must be talking about different things. If your waveform is 2500

points, and takes 73.5 KB, that works out to 29.4 bytes per point.

Sounds like very high resolution! Even if that waveform was transferred

in some ASCII format, that is still very verbose.

I've never tried to measure the GPIB throughput, but I am fairly certain

that the overall throughput in any case that I've encountered is limited

by the scope itself, and the operation of the scope in terms of its

triggering setup and the signal it is measuring. On some scopes (eg TDS

380), I can swamp it's CPU with GPIB communications, and effectively

cripple its functionality. That is an old scope, and I doubt that modern

scopes would be similarly afflicted. Perhaps the hardcopy function would

be a good case for a throughput test.

   ---   rod.

Pavel Masloff wrote:

Hi Rod,

We have 2500 points per waveform. Our PCs are equipped with COM ports
only, no GPIB cards. One waveform is 73,5 KB to be exact. The RS232
connection speed is maximum 19200 Kb/s at maximum. For the time being I
just want to check whether the experiment went fine, no false
triggering, etc. In the future, I would like to analyze the waveforms in
matlab via CA. So this will be handy.
What is the speed of the GPIB interface on Tek scopes, anyway?

On Fri, May 4, 2012 at 1:42 AM, Rod Nussbaumer <[email protected]
<mailto:[email protected]>> wrote:

    Pavel:

    Every Tektronix scope I've set up communications with had a 500
    point waveform (as well as some substantially larger ones).
    Presently, I'm acquiring those at 10 waveforms per second (over
    GPIB). Are you sure that would not suffice for you? Is GPIB an
    option? Much much faster.

       ---   rod.

    Pavel Masloff wrote:

        Mark,

        A waveform weighs 70kB. 4 waveforms = 280 kB. 280 vs 40. I would
        have to
        wait a couple of minutes till the data is processed. 10-15
        seconds for
        the screen dmp.

        On Thu, May 3, 2012 at 11:13 PM, Mark Rivers
        <[email protected] <mailto:[email protected]>
        <mailto:[email protected].__edu
        <mailto:[email protected]>>> wrote:

            It may be time to back up a step.  Why not transfer the
        waveforms
            themselves, rather than a screen dump?  There are others in the
            EPICS community who have already done that for the scopes
        you are using.

            __ __

--
Best regards,

Pavel Maslov, MS
Controls Engineer at Pulsed power Lab
Efremov Institute for Electro-Physical Apparatus
St. Petersburg, Russia

Mobile: +7 (951) 672 22 19
Landline: +7 (812) 461 01 01

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System