OPC UA Client

OPC UA Client To offer a more generic interface, the Automation Connect tool has a build-in OPC UA client. This is typically interesting if you want to benefit from Automation Connect in a non-Siemens automation environment. As the steps for connecting to an OPC UA Server are a little bit more extensive, all necessary controls are shifted to a single new dialog, which can be opened by the single Connect (or later Settings) button in the OPC UA tab.

The OPC Dialog itself consists of 5 basic elements (see figure below):

• An address bar for defining an OPC Server endpoint at the top.

• A tree-structure for browsing a connected OPC UA server at the left.

• An information field for listing all attributes of a selected element at the right.

• A Variable list for listing all selected and monitored variables at the bottom.

• A status bar beneath that at the bottom.

Figure 38: OPC UA dialog overview

Connecting an OPC UA server to the Automation Connect tool

Connecting the Automation Connect tool to an OPC UA Server can be achieved through the following steps:

1. Enter a discovery server address (see figure Figure 39, left).

Figure 39: Connection to an OPC UA server

2. Select the appropriate server endpoint in the dropdown menu (see figure Figure 39, left).

3. Press the Connect button.

4. Enter the session / authentication information (see figure Figure 39, right).

5. Browse and select the server variables (see figure Figure 40).

Figure 40: OPC UA client register session and browse

6. Confirm the selection.

Figure 41: OPC UA client variables

OPC UA time synchronization

OPC UA time synchronization Although not standardized, the Automation Connect tool provides a customized way to synchronize with other simulations using OPC UA. This time synchronization can be achieved by exchanging different control- and status-variables through the OPC UA server. For a complete setup you need to define two control and one feedback variable(s):

• Control - Simulation time: this double / LREAL value provides the current simulation time for all other simulating systems.

• Control - Clients start simulating: this boolean value is used as a command to all other connected systems to start their simulation and simulate until the destiny simulation time provided by the previous control variable.

• Feedback - Clients finished simulating: this boolean value works as a feedback regarding the simulation status of the other systems. Note that after commanding the start for the other systems (using the previous control variable), a change from true to false is considered as an acknowledgment that the other systems started their simulation. A second change back to true then is considered as the concluding feedback that all linked systems have finished.

All those control variables can be defined in the monitored variables list inside the OPC dialog. To define such a synchronization variable, simply right click an a suitable monitored variable and select the relevant setting in the Mark as synchronization variable menu (see following figure). Note that control variables need to be writable while the feedback variable needs to be readable as well as that the simulation time control needs to be of type double while the other two need to be boolean variables.

Such defined variables are colored yellow and are renamed according to their synchronization relevance. to undo the settings, right click the relevant variable again an mark as None.

Figure 42: OPC UA client defining synchronization variables