[time-nuts] Rb as source for ADEV?

Bob Camp lists at rtty.us
Sun Feb 9 19:25:18 EST 2014


Hi

If both / all  of the counters are collecting 1 second data, the GPIB stuff isn’t going to be to bad … 

There’s always an If.  You need to run the counters so they do it all automatically (arm etc). That’s the way it’s normally done It should not be to big a constraint. The rest of it turns into a poll this poll that loop. When one of the counters has data you grab it and shove it into a file someplace. 

The counters buffer the data, so they only get bothered if the poll / read process gets to a significant fraction of a second. They started out doing HPIB / GPIB with some *very* slow hardware. The 5335 and 5334 date to that era. They have been fully debugged with gear that waits a while to grab data from them.

If you are running a lot faster then yes… you can get into issues. 

Bob


On Feb 9, 2014, at 4:28 PM, Bob Stewart <bob at evoria.net> wrote:

> 
> Hi Orin,
> 
> No,
> it's not a matter of just talking to the device.  I can to that.  The 
> problem happens when you want more than one program/process to access 
> the GPIB bus at the same time; e.g. running two different tests.  For 
> that you have to have a server process which manages the interface and 
> relays packets to the clients.  Prologix hadn't written one when they 
> commented here last summer.
> 
> Bob
> 
> 
> 
> 
> 
>>> ________________________________
>>> From: Orin Eman <orin.eman at gmail.com>
>>> To: Bob Stewart <bob at evoria.net>; Discussion of precise time and frequency measurement <time-nuts at febo.com> 
>>> Sent: Sunday, February 9, 2014 12:55 PM
>>> Subject: Re: [time-nuts] Rb as source for ADEV?
>>> 
>>> 
>>> 
>>> Bob,
>>> 
>>> 
>>> If you want a C++ class to talk to the Prologix Ethernet, I have one.  (I don't have a USB version, but that would just be a matter of implementing a simple subclass to do the communication with the device.)
>>> 
>>> 
>>> I also have code that uses the above and talk to a 5335A and to a 5370A, both of which like to sulk if you don't do things in the right order.
>>> 
>>> 
>>> It's written for Windows and should compile in the _free_ Visual Studio Express 2012 (it used to, but the last time I built it was with the full version).  Porting to Linux/Mac/iOS would be easy enough... maybe I'll do iOS for fun, if Xcode doesn't sulk and stays alive long enough that is; the only thing Xcode does fast for me is crash!
>>> 
>>> 
>>> Licensing for all but the findAdapters method will be LGPL once I put headers in.  findAdapters() is derived from John Miles's GPIB library and subject to its licensing.
>>> 
>>> 
>> 
>> 
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