ReadAsyncFcn - Callback function file to execute when asynchronous read completes

Description

You configure ReadAsyncFcn to execute a callback function file when an asynchronous read operation completes. You execute an asynchronous read with the readasync function. A read async event occurs immediately after the data is returned by the server to the MATLAB workspace.

When a read async event occurs, the function specified in ReadAsyncFcn is passed two parameters: Obj and EventInfo. Obj is the object associated with the event, and EventInfo is an event structure containing the fields Type and Data. The Type field is set to 'ReadAsync'. The Data field contains a structure with the fields defined below.

FIeld Name	Description
LocalEventTime	The time, as a MATLAB date vector, that the event occurred.
TransID	The transaction ID for the asynchronous read operation.
GroupName	The group name.
Items	A structure containing information about each item whose value or quality updated.

The Items structure contains the fields defined below.

FIeld Name	Description
ItemID	The item name.
Value	The data value.
TimeStamp	The time, as a MATLAB date vector, that the server's cache was updated.

Read async event information is stored in the EventLog property.

Characteristics

Access	Read/write
Applies to	dagroup
Data type	string, function handle, or cell array
Values	The default value is @opccallback.

See Also

Functions

opccallback, readasync

Properties

EventLog

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