opcif_unregister()

   #include opcapi.h

   int opcif_unregister(
              int              interface_id,        /* in */
              long             cond_id              /* in */
                       );

Parameters

interface_id

Specifies which interface instance is used.

cond_id

Specifies the registration condition to be removed. 0 unregisters for all messages, message events, or application responses.

Description

To cancel prior registrations for messages, the external application calls opcif_unregister() with the value of reg_cond that was specified in the call to the registration API. As the registration mechanism is a positive filter, removing a registration condition does not mean that messages matched by this condition are filtered out after opcif_unregister() is called. Instead, just the positive filter condition is cancelled.

By unregistering a condition for message events or application responses, information matching the unregistered condition will no longer received.

Return Values

OPC_ERR_OK

OK.

OPC_ERR_CANT_INIT

Initialization of queues failed.

OPC_ERR_INVALID_INTERFACE_ID

No such interface opened.

OPC_ERR_CANT_INFORM_MSGM

Informing message manager failed.

Versions

HPOM for Windows 8.00 and higher