An OPC UA Client can use standard OPC UA Services to browse and access POWERLINK Objects defined in this document.
Possible use cases for this access are diagnostics, condition monitoring, configuration management, visualisation etc.
Figure 6 shows logical links between an OPC UA Client and a POWERLINK Object Dictionary.
Figure 6 – Logical links between OPC UA Client and POWERLINK Object Dictionary
Since OPC UA Clients are typically operating in standard Ethernet networks using CSMA/CD and the POWERLINK network uses SCNM the physical connection will be established through standard TCP/IP routing mechanisms which may be implemented on the POWERLINK Managing Node (Figure 7) or on a POWERLINK Controlled Node (Figure 8).
Figure 7 – Connection through bridge on POWERLINK Managing Node
Figure 8 – Connection through bridge on a POWERLINK Controlled Node
Another option to access POWERLINK Objects is an OPC UA Server that represents a group of POWERLINK Devices within one Information Mode l as shown in Figure 9.
Figure 9 – Connection to aggregated Information Model
The SDO protocol defined by POWERLINK is a Client/Server protocol to access POWERLINK Objects in a POWERLINK Object Dictionary, but this protocol does not support security.
The definition of SDO services over OPC UA allows secure SDO connections between POWERLINK Devices using the standard security mechanisms provided by OPC UA.
Figure 10 – SDO access through untrusted networks