Experimental Physics and
Industrial Control System

Jens Eden <[email protected]> · Wed, 13 Dec 2000 19:03:36 +0100

Dear all,

I am using the CA-Server (EPICS R3.13.3) on Linux and Windows and
encountered the following problem.
Reading an array with caget works fine, but trying to read the same
array via a CDEV/CA-client results in an internal error on the server
(you can easily verify this with the simple server in the
src/cas/example/simple-directory). 

As far as I understand, the CDEV/CA-client always uses the DBR_CTRL_XXX
type to request data. The CA-Server checks the application-type and uses
the corresponding prototype gdd-object (gddcontainer for dbr_ctrl_xxx),
which is defined in gddAppsDef.cc. But the value-gdd in the gddcontainer
is defined as of type gddScalar. The CA-Server can't modify the bounds
and type of the value-gdd, because it is managed and flattened ==>
internal error.

Maybe a solution could be to differentiate between array and scalar
dbr_ctrl-prototypes, when registering them in the
gddApplicationTypeTable? 
My first approach was, to unmark the Managed/Flat-flags of the
gddContainer, to be able to change bounds and type of the value-gdd. It
works, but it is a performance impact and I am not really happy with it.

Has anyone else encountered the same problem, or any suggestions?

Jens

-------------------------------

Jens Eden; PTB

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System