This property is read-only.
EventLog contains a structure array that stores information
related to Industrial Communication Toolbox™ software events. Every element in the structure array corresponds to an
event.
Each element in the EventLog structure contains the fields
Type and Data. The Type value
can be 'WriteAsync', 'ReadAsync',
'CancelAsync', 'Shutdown',
'Start', 'Stop', or
'Error'.
Data stores event-specific information as a structure. For
information on the fields contained in Data, refer to the associated
callback property reference pages. For example, to find information on the fields
contained in Data for a Start event, refer to the StartFcn property.
You specify the maximum number of events to store with the EventLogMax property.
Note that some events are not stored in the EventLog. If you want
to store these events, you must specify a callback for that event.
You can execute a callback function when an event occurs by specifying a function
for the associated callback property. For example, to execute a callback when a read
async event is generated, you use the ReadAsyncFcn property.
If the event log is full (the number of events in the log equals the value of the
EventLogMax property) and a new event is
received, the oldest event is removed to make space for the new event. You clear the
event log using the cleareventlog function.
Example
The following example creates a client and configures a group with two items. A
30-second logging task is run, and after 10 seconds the item values are read. When the
logging task stops, the event log is retrieved and examined.
da = opcda('localhost', 'Matrikon.OPC.Simulation');
connect(da);
grp = addgroup(da, 'EvtLogExample');
itm1 = additem(grp, 'Random.Real8');
itm2 = additem(grp, 'Triangle Waves.UInt1');
set(grp, 'UpdateRate', 1, 'RecordsToAcquire', 30);
start(grp);
pause(10);
tid = readasync(grp);
wait(grp);
el = get(da, 'EventLog')
el = get(da, 'EventLog')
el =
1x3 struct array with fields:
Type
DataNow examine the first event, which is the start event.
el(1)
ans =
Type: 'Start'
Data: [1x1 struct]The Data field contains the following information.
el(1).Data
ans =
LocalEventTime: [2004 1 13 16 16 25.1790]
GroupName: 'EvtLogExample'
RecordsAcquired: 0The second event is a ReadAsync event. Examine the
Data structure and the first element of the
Items structure.
el(2)
ans =
Type: 'ReadAsync'
Data: [1x1 struct]
el(2).Data
ans =
LocalEventTime: [2004 1 13 16 16 35.2100]
TransID: 2
GroupName: 'EvtLogExample'
Items: [2x1 struct]
el(2).Data.Items(1)
ans =
ItemID: 'Random.Real8'
Value: 2.4619e+003
Quality: 'Good: Non-specific'
TimeStamp: [2004 1 13 16 16 35.1870]Data Types: struct
