Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Thu, 7 Nov 2002 18:25:41 +0100

Yes - that's a frequent problem.

Apart from pointing out that the future might bring freedom of this
limitation... 

.... well, you might also be able to use a technique similar to what I
described to Rok Sabjan in July, which is actually quite close to Ned's
first suggestion.

 http://www.aps.anl.gov/epics/tech-talk/2002/msg00393.php

Ralph

>>>>> "Ned" == Ned Arnold <[email protected]> writes:

  > This has come up often ...

  > The MBBO record is limited to 16 values because all
  > enumerated values passed by channel access are limited 
  > to 16 states (MAX_ENUM_STATES). If this is changed, everything
  > breaks.

  > There aren't any "perfect" work arounds. Here are two I have 
  > seen used:

  > 1) If you want strings on a menu, define multiple MBBO's to 
  >    cover as many as you need. A unique value can be calculated
  >    in the database depending on which MBBO changed. Unfortunately, 
  >    all clients that want to use these PVs will have to decide which 
  >    PV to write to. 

  >    For an operator GUI, a TCL/TK application can be written that 
  >    provides ALL menu choices and writes to the appropriate PV.

  > 2) If you can do without strings, use a longout record that can
  >    then fanout to calc records and mbbo's to determine the
  >    appropriate action.   

  >    	Ned

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System