Experimental Physics and
Industrial Control System

[email protected] (Frank Lenkszus) · Wed, 24 Aug 1994 09:16:01 -0600

The jitter for events out of the sequence ram is primarily dependent on
the clock frequency chosen for the sequence.  Our design spec called for a max
event sequence clock rate of 1MHz (but we've run them at 2-3 MHz).  In addition
to the sequence ram clock there is the sampling jitter of the 10MHz event
clock. 

BTW, jitter can be spec'd as peak to peak or rms.  You often see rms figures
on equipment specs which are much less than peak to peak jitter.  Any way, with
a 1 MHz sequence ram clock you can expect a peak to peak jitter of ~1.1 usec.

You can get down to ~0.1 usec peak to peak jitter if you use one of the event
generators external inputs to generate the event. There are 8 external 
prioritized event inputs.  

All the above refers to hardware timing pulse generation, transmission and 
reception via the event system.

Record processing in response to an event is an entirely different matter.  I'm
not even sure what jitter means in that context but would expect it to be 10's 
to 100's of microseconds and wouldn't be suprised at milliseconds depending
on what's going on in the ioc at the time.

We do not rely on software and record processing for timing except in the most
relaxed cases where 10's of milliseconds of latency would be of no consequence.

Frank

------
Frank Lenkszus	 [email protected]  (708) 252-6972
Advanced Photon Source -- Controls --  Argonne National Laboratory

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System