This OPC UA ObjectType represents an AutoID Device. It defines all methods and properties required for any kind of AutoID Device in 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.
Figure 6 shows an overview for the AutoIdDeviceType with its Properties and the base type DeviceType. It is formally defined in Table 7.
Figure 6 – AutoIdDeviceType overview
There are several options to start the scanning of AutoID Identifiers like transponders or codes. The access to the different options requires that the OPC UA Client and the user are authorized to access the requested information.
Option 1: The reader starts the scanning when the Client calls the Scan Method. The operation stops according to the termination conditions specified in the Settings parameter of the Method. The scanned data will be the result of the method call. The Settings parameter has the DataType ScanSettings. The DataType is defined in 9.3.7. Only the OPC UA Client calling the Method receives the scanned data.
Option 2: The reader will throw Events at 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 Settings parameter of the Method, or if the client calls the ScanStop Method. The scanned data is delivered through the Events. Every OPC UA Client subscribed for Events will receive the scanned data.
Option 3: The reader will throw Events at 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 scan Methods has to be called. The scanned data is delivered through the Events. Every OPC UA Client subscribed for Events will receive the scanned data.
Option 4: The reader starts the scanning when the Client writes True to 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 Clients limited to Data Access functionality. Additional Scan result information can be provided via Variables like LastScanTimestamp, LastScanAntenna and 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 Server shall set all Variable SourceTimestamps and the value of the LastScanTimestamp Variable with a consistent value if the Variables Values are updated. An OPC UA Client must ensure that it has a constent set of Values. The Client can use the DataChangeFilter STATUS_VALUE_TIMESTAMP_2 to receive updates for all Variables to verify if all necessary information is available or a Client can subscribe only for one Variable like LastScanData and then read the related Variables including a verification of the SourceTimestamp.
Depending on the AutoID Device capabilities, the Scan, ScanStart and ScanStop Methods are optional. If none of these methods are implemented, option 3 or 4 has to be supported. See also 10.1 for the definition of the different AutoID Device Profiles.