This OPC UA ObjectTyperepresents an AutoID Device.It defines all methods and properties required for any kind of AutoID Devicein general, e.g. methods for controlling the scan operation or the mechanism to load a configuration file to the reader. However, the object is an abstract definition in terms of the actual AutoID technology, i.e. there are no properties or methods which rely on specific features or technologies.
There are several options to start the scanning of AutoID Identifierslike transponders or codes. The access to the different options requires that the OPC UA Clientand the user are authorized to access the requested information.
Option 1: The reader starts the scanning when the Clientcalls the Scan Method. The operation stops according to the termination conditions specified in the Settingsparameter of the Method. The scanned data will be the result of the method call. The Settingsparameter has the DataType ScanSettings. The DataType is defined in 9.3.7. Only the OPC UA Clientcalling the Methodreceives the scanned data.
Option 2: The reader will throw Eventsat each time a transponder or code has been detected. The scan operation starts when the client calls the ScanStart Method. The operation stops according to the termination conditions specified in the Settingsparameter of the Method, or if the client calls the ScanStop Method. The scanned data is delivered through the Events. Every OPC UA Clientsubscribed for Eventswill receive the scanned data.
Option 3: The reader will throw Eventsat each time a transponder or code has been detected. The scan operation is controlled by the reader itself, e.g. by a trigger button. In this case, none of the scanMethodshas to be called. The scanned data is delivered through the Events. Every OPC UA Clientsubscribed for Eventswill receive the scanned data.
Option 4: The reader starts the scanning when the Clientwrites Trueto the Variable ScanActive. The scan result is provided through the Variable LastScanData. The configuration is provided through the parameters in the FunctionalGroup ScanSettings. The simple option has several limitations and is only used with OPC Clientslimited to Data Accessfunctionality. Additional Scan result information can be provided via Variables like LastScanTimestamp, LastScanAntennaand LastScanRSSI, where the last two Variables are only offered by the RfidReaderDeviceType. OPC UA does not ensure a consistent delivery of a list of Variable Values. An OPC UA Servershall set all Variable SourceTimestampsand the value of the LastScanTimestamp Variablewith a consistent value if the Variables Valuesare updated. An OPC UA Client must ensure that it has a constent set of Values. The Clientcan use the DataChangeFilterSTATUS_VALUE_TIMESTAMP_2 to receive updates for all Variablesto verify if all necessary information is available or a Clientcan subscribe only for one Variablelike LastScanDataand then read the related Variablesincluding a verification of the SourceTimestamp.
Depending on the AutoID Devicecapabilities, the Scan, ScanStartand ScanStop Methodsare optional. If none of these methods are implemented, option 3 or 4 has to be supported. See also 10.1for the definition of the different AutoID Device Profiles.