[time-nuts] Timelab, two SR620s and losing samples

Attila Kinali attila at kinali.ch
Sun Jan 17 04:46:51 EST 2016


Moin John,

On Sat, 16 Jan 2016 13:33:54 -0800
"John Miles" <john at miles.io> wrote:

> Agreed with Magnus that there are a lot of possible variables in your setup 
> that need to be ruled out.  

Yes, too many. And it isn't really helping that I hardly understand what
I am doing.


> Are you using the SR620 driver in TimeLab, or did you find a way to get
> it to emit data continuously via the RS232 port for use with the talk-only
> driver?

I am using TimeLab and start two acquisitions. That part seems to work
quite nicely.

> I've seen occasional instances where a counter has ignored every other
> trigger when used in addressable mode by TimeLab.  It's not always readily 
> reproducible, but the counter drivers in the current beta at 
> http://www.miles.io/timelab/beta.htm seem to be a bit less prone to that 
> behavior.  If you aren't already using the beta, try that.

Thanks! I'll try that tomorrow.

> 
> It's always safest to use counters in talk-only mode when possible, since 
> that rules out any timing problems that might arise in a two-way GPIB or 
> serial conversation where each individual reading is requested by the 
> software as done by the 5313xA, Philips, DTS2070-series, and SR620 drivers.  
> Some of those counters can be used in both talk-only and addressable modes, 
> but I don't believe that's true of the SR620, unfortunately.  All of the 
> programming examples in the SR620 manual work by requesting each reading 
> individually. 

Hmm.. I have set TimeLab to do samples every 0.1 seconds, and have an
external trigger with the same interval (SR620 setting ist Ext +/- Time).
Could it be that TimeLab just samples a little slower than the 0.1s,
so that it misses a measurement once in a while and has to wait until
the next trigger arrives?


			Attila Kinali

-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson



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