In Figure 7 an overview of the IO-Link Information Model is given. The IOLinkDeviceType represents IO-Link Devices. In case no IODD is available, this type shall directly be used to represent an IO-Link Device. If an IODD is available, a subtype is used representing the concrete IODD and providing the additional parameters, system commands, etc. defined in the IODD (see section 7.3). The IOLinkDeviceType inherits from TopologyElementType defined in OPC 10000-100 and thus provides basic grouping mechanisms (ParameterSet for parameters and MethodSet for Methods). It also uses basic Properties of a device like SerialNumber defined in OPC 10000-100. Section 7.1 defines details on those Properties and additional Properties like VendorId, Parameters like ApplicationSpecificTag and Methods like ReadISDU. The IO-Link Master is represented by an Object of IOLinkMasterType (see section 7.5). This ObjectType also inherits from the TopologyElementType and defines basic Properties, Parameters and Methods. For each port the IO-Link Master contains an Object of type IOLinkPortType (see section 7.6). The IOLinkPortType inherits from the TopologyElementType and thereby uses the same grouping mechanisms for Parameters and Variables. It defines Properties, Parameters and Methods for the IO-Link Port. If the port has an IO-Link Device connected, the IO-Link Device (Object of type IOLinkDeviceType) is connected to the port.
Figure 7 – IO-Link Information Model overview (Structure)
Instances of IOLinkDeviceType generate Events of type IOLinkDeviceEventType (see section 9.3) and IOLinkDeviceAlarmType (see section 9.8). An OPC UA Server might provide instances of the IOLinkDeviceAlarmType or its subtypes as Objects under the Alarms Object (see Figure 8).
Instances of IOLinkMasterType generate Events of type IOLinkMasterEventType (see section 9.6) and IOLinkMasterAlarmType (see section 9.11). Ports generate events of type IOLinkPortEventType (see section 9.5) and IOLinkPortAlarmType (see section 9.10). Both can provide instances of the IOLinkMasterAlarmType respectively IOLinkPortAlarmType under the Alarms Object (see Figure 8).
In the ObjectType hierarchy the mentioned events are grouped under the IOLinkEventType and the alarms under the IOLinkAlarmType (see Figure 8).
Figure 8 – IO-Link Information Model overview (Events)
Figure 9 shows the entry points into the AddressSpace. The IOLinkMasterSet provides direct access to the Objects representing IO-Link Masters and indirectly to the Objects representing the IO-Link Devices connected to the Master. The IODDManagement Object contains the Object named IODDs pointing to all ObjectTypes representing an IODD.
Note: In order to figure out how many IO-Link Masters an OPC UA Server currently manages, an OPC UA Client can browse the IOLinkMasterSet and count all Objects of IOLinkMasterType or a subtype of it.
Figure 9 – AddressSpace entry points