Experimental Physics and
Industrial Control System

> If the count in ca_create_subscription is > 1 and the type is
> DBR_TIME_STRING, is the event_handler_args.dbr->value set to an array of
> strings?

Yes, an array of dbr_string_t - each element is a fixed length buffer of
size dbr_string_t, but a variable length nill terminated string is stored
therein.

> Also, when I try to do a ca_create_subscription on the excas pv named
> albert (1000 elements), I get from the SEVCHK:
> 
> CA.Client.Exception...............................................
>     Warning: "The requested data transfer is greater than available
> memory
> or EPICS_CA_MAX_ARRAY_BYTES"
>     Context: "ca_create_subscription"
>     Source File: ../ca_monitor.cpp line 163
>     Current Time: Fri Jan 28 2011 13:23:19.178091145
> ..................................................................
> 
> However, if I run the included camonitor tool on albert, it works fine.
> Would this be because I am requesting the subscription with the
> DBR_TIME_STRING?

Yes, string arrays use quite a bit of space compared to doubles. In R3.14
you can set EPICS_CA_MAX_ARRAY_BYTES in the environment of both the client
and the IOC to extend the limit.

Jeff
______________________________________________________
Jeffrey O. Hill           Email        [email protected]
LANL MS H820              Voice        505 665 1831
Los Alamos NM 87545 USA   FAX          505 665 5107

Message content: TSPA

With sufficient thrust, pigs fly just fine. However, this is
not necessarily a good idea. It is hard to be sure where they
are going to land, and it could be dangerous sitting under them
as they fly overhead. -- RFC 1925


> -----Original Message-----
> From: [email protected] [mailto:tech-talk-
> [email protected]] On Behalf Of [email protected]
> Sent: Friday, January 28, 2011 2:31 PM
> To: [email protected]
> Subject: ca_create_subscription element count
> 
> Hi,
> 
> If the count in ca_create_subscription is > 1 and the type is
> DBR_TIME_STRING, is the event_handler_args.dbr->value set to an array of
> strings?
> 
> Also, when I try to do a ca_create_subscription on the excas pv named
> albert (1000 elements), I get from the SEVCHK:
> 
> CA.Client.Exception...............................................
>     Warning: "The requested data transfer is greater than available
> memory
> or EPICS_CA_MAX_ARRAY_BYTES"
>     Context: "ca_create_subscription"
>     Source File: ../ca_monitor.cpp line 163
>     Current Time: Fri Jan 28 2011 13:23:19.178091145
> ..................................................................
> 
> However, if I run the included camonitor tool on albert, it works fine.
> Would this be because I am requesting the subscription with the
> DBR_TIME_STRING?
> 
> Thank you again for your time,
> Patrick

References:

ca_create_subscription element count pthomas

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