Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Thu, 21 Oct 2010 12:07:04 -0400

 On 21.10.2010 11:21, Steven M. Hartman wrote:

The ai and ao records included in base support a breakpoint table
facility which may be adequate for your needs. But this conversion is
to/from RVAL (which is an int) and VAL (which is a double). I hacked a
bpt record (based on the ai record) which used the break point table
functions included in base to do double to double conversions for my
needs. In this way, everything was done in the EPICS database (no
sequencer, no subroutine records, etc).

RVALs are integer, of course - now I start remembering .... stupid me.
For a similar application (global tune feed-forward from all ID gaps
towards multiple families of quadrupoles) Benjamin Franksen at BESSY
created a new record called cvtRecord to handle large 1/2D feed-forward
tables in a generic way:

/*

* General Remarks

* ===============

*

* This record type supports conversion of one or two floating point values

* into one resulting floating point value. The field METH specifies
the kind

* of conversion: LINEAR, via a custom SUBROUTINE, or via one- (1D) or

* two-dimensional (2D) conversion TABLE. More specifically, if METH is

*

* menuCvtMethodLinear:

* VAL = XSLO * X + YSLO * Y + VOFF

*

* menuCvtMethodSubroutine:

* SPEC should be the name of a global subroutine. CSUB is set to the

* address of the subroutine.

* VAL = CSUB(X, Y, &DPVT)

*

* menuCvtMethod1DTable:

* menuCvtMethod1DTableInverted:

* menuCvtMethod2DTable:

* Conversion uses the csm module. SPEC should be the filename

* of the table. CSUB is set to the csm_function handle returned by
csm.

* VAL = csm_y(CSUB, X) for one-dimensional tables

* VAL = csm_x(CSUB, Y) for one-dimensional inverted tables

* VAL = csm_z(CSUB, X, Y) two-dimensional tables

*/

You should probably ask [email protected] for the details and
the code to this record (and the "csm" module it uses) if you are
interested.
~Ralph

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System