(Not recommended) Preview most recently acquired data
Support for the OPC Data Access (DA) standard will be removed in a future release. Instead use OPC Unified Architecture (UA). See Compatibility Considerations.
S = peekdata(GObj,NRec)
S = peekdata(GObj,NRec) returns the
NRec most recently acquired records for the
GObj, without removing
those records from the toolbox engine.
GObj must be a scalar
S is a structure array
containing data for each record, in the same format as the structure returned by
NRec is greater than the number of records currently
available, a warning will be generated and all available records will be
peekdata when you want to return logged data but you do
not want to remove the data from the buffer. The object's
RecordsAvailable property value will not be affected by the
number of samples returned by
peekdata is a non-blocking function that immediately returns
records and execution control to the MATLAB® workspace.
Configure and start a logging task for 60 seconds of data.
da = opcda('localhost','Matrikon.OPC.Simulation'); connect(da); grp = addgroup(da,'ExOPCREAD'); itm1 = additem(grp,'Triangle Waves.Real8'); itm2 = additem(grp,'Saw-Toothed Waves.Int2'); grp.LoggingMode = 'memory'; grp.RecordsToAcquire = 60; start(grp);
Wait for 2 seconds and peek at the two most recent records.
pause(2); s = peekdata(grp,2) s.Items(1).Value