readAtTime
Read historical data from nodes of OPC UA server at specific times
Syntax
UaData = readAtTime(UaClient,NodeList,TimeVector)
UaData = readAtTime(NodeList,TimeVector)
Description
UaData = readAtTime(UaClient,NodeList,TimeVector)
reads stored historical data from the nodes given by NodeList
, at
the specified times in TimeVector
. NodeList
is
an array of OPC UA node objects, which you can create using
getNamespace
, browseNamespace
, or
opcuanode
. TimeVector
is an array of
MATLAB datetimes or date numbers.
UaData
is returned as a vector of OPC UA data objects. The
server interpolates or extrapolates data if it is not stored at the times specified
in TimeVector
. Data Quality is set appropriately for interpolated
data. If readHistory
fails to retrieve history for a given
node, that node is not included in the returned OPC UA data object, and a warning is
issued. If all requested nodes fail, an error is generated.
UaData = readAtTime(NodeList,TimeVector)
reads from the nodes identified by NodeList
. All nodes must be of
the same connected client.
OPC UA servers provide historical data only from nodes of type
Variable
. If you attempt to read values from an
Object
node, no data is returned for that node, the status
for that node is set to Bad:AttributeNotSupported
, and the node
is not included in the returned UaData
object.
Examples
Retrieve the 10 minute sampled history for the current day from a local server.
uaClnt = opcua('localhost',62550); connect(uaClnt); nodeId = '1:Quickstarts.HistoricalAccessServer.Data.Dynamic.Double.txt'; nodeList = opcuanode(2,nodeId,uaClnt); TimeVector = datetime('today'):minutes(10):datetime('now'); dataObj = readAtTime(uaClnt,nodeList,TimeVector);
Version History
Introduced in R2015b