Experimental Physics and
Industrial Control System

Benjamin Franksen <[email protected]> · Sat, 9 Apr 2011 00:36:39 +0200

Hello,

the devMbboSoftRaw outputs the RVAL field (which has type DBF_ULONG) with
request type DBR_LONG. This means that if you point the OUT link to a calc
record's A field, an RVAL of e.g. 0xffff0000 (all 16 bits set, left shifted by
16) will result in a negative value. OTOH, if you use the INPA input link to
get the value, then A will contain a positive number, because the request type
in this case is DBR_DOUBLE. This behaviour is somewhat surprising to the
uninitiated. Off-hand, I do not know of a good way to fix this, but maybe
someone else has an idea?

(Life would be *so* much simpler if CA had been designed with support for
unsigned integer types. And, just BTW, as it stands CA for EPICS V4 (a.k.a.
pvAccess+pvData) will have exactly the same sort of problems. That is, unless
we promise that servers never use unsigned integer types for publicly
accessible record or struct fields.)

Cheers
Ben

________________________________

Helmholtz-Zentrum Berlin für Materialien und Energie GmbH

Mitglied der Hermann von Helmholtz-Gemeinschaft Deutscher Forschungszentren e.V.

Aufsichtsrat: Vorsitzender Prof. Dr. Dr. h.c. mult. Joachim Treusch, stv. Vorsitzende Dr. Beatrix Vierkorn-Rudolph
Geschäftsführer: Prof. Dr. Anke Rita Kaysser-Pyzalla, Prof. Dr. Dr. h.c. Wolfgang Eberhardt, Dr. Ulrich Breuer

Sitz Berlin, AG Charlottenburg, 89 HRB 5583

Postadresse:
Hahn-Meitner-Platz 1
D-14109 Berlin

http://www.helmholtz-berlin.de

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System