Experimental Physics and
Industrial Control System

"Jeff Hill" <[email protected]> · Thu, 7 Mar 2002 19:04:16 -0700

This is an EPICS bug report.

Credit:

Thanks to Tim Mooney, Ron Sluiter, and Mark Rivers for discovering the
problem and following through with an excellent bug report.

Effected versions: 

Almost all recent EPICS versions that promote the native type of
unsigned database fields to the next larger integer or floating point
type, because Channel Access clients use only signed types, are
effected. 

The problem is further restricted only to Channel Access clients that
run within a vxWorks IOC communicating with local database fields stored
in some unsigned integer type. 

Furthermore, the CA client must enter a subscription with an external
type that is identical to the CA "native" type only when the CA "native"
type is promoted to some larger signed type from the fields unsigned
integer field type.

The majority of EPICS users use only two CA client programs that attach
to local in-memory process variables: The sequencer and the CA based
database links. Both of these clients install monitor subscriptions that
include timestamp and or alarm information. Therefore, they do not
monitor in a native promoted type as described above, and are therefore
not involved.

Likely symptom: 

A field contiguous with a field in the database with an unsigned integer
type is mysteriously damaged. 

Resolution:

I have committed a patch to CVS. The APS will be making a new EPICS
R3.13 release available soon.

Jeff
__________________________________________________________
Jeff Hill                     Internet     [email protected]
LANL MS H820                  Voice        505 665 1831
Los Alamos NM 87545 USA       FAX          505 665 5107

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System