Experimental Physics and
Industrial Control System

Ralph Lange <[email protected]> · Tue, 14 Jun 2005 11:35:01 +0200

Hi Huang Song,
Your problem is based on a simple misunderstanding: The IOC timestamps
are so closely related to the matching data, that for Channel Access
timestamps are part of the data structure, not the event structure.
I.e., the void pointer dbr inside the event_handler_args points to the
value, which is embedded in one of the many different DBR_... types -
you will get your data in the DBR type that you specify when subscribing
to a channel. If you subscribe requesting DBR_TIME_... data, you will
get the timestamp and the related value in one structure that dbr points to.
Check the CA Reference Manual (under Channel Access Data Types) or
db_access.h for the available types and their respective data structures.
Good luck!
Ralph

huangsong wrote:
Hello, everyone
I'm now programming using channel access client library. By CA Monitor, we can get the
event messages after we use ca_add_masked_array_event() to register on some PVs.
If there are some events triggered, we get messages which include things like:
channel name
pv values
status

But in the messages, I can't get the exact IOC time when it trigger the event.
The event_handler_args defined like this in cadef.h:
typedef struct  event_handler_args{
       void            *usr;   /* User argument supplied when event added      */
       struct channel_in_use
                       *chid;  /* Channel id                                   */
       long            type;   /* the type of the value returned               */
       long            count;  /* the element count of the item returned       */
       READONLY void   *dbr;   /* Pointer to the value returned                */
       int             status; /* ECA_XXX Status of the requested op from server       */
}evargs;

Is there any parameter including the exect time on IOC when the event triggered?
I hope it should not be the responsibility of Event Handler routines.

Best wishes and regards,
Huang song
IHEP
 [email protected]

2005.06.06

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System