Tab: Communication, via OPC UA Server

“Where to find the server layout”
“Browse Live Server”:	The client connects to the server and detects the existing variables and types.
“From Information Model”	The client reads the data structure (layout) of the OPC UA Server from the information model set here and as a result receives the information about available variables and types. A connection to the server is not required. The list box contains the information models installed in the ⮫ OPC UA Information Model Repository.

“Read Connection Settings from IEC Variable”	: The connection settings used by the device are not read here from the dialog, but at runtime from the IEC variable specified here. For this possibility, see: ⮫ “Using a Dynamic Connection to an OPC UA Server ”

Connection Type
“Server URl”	URI of the OPC UA Server; editable
“Show All Endpoints”	The button opens the “Available Endpoints” dialog with the end points available on the OPC UA Server. An "endpoint" is a combination of security settings. The lower part of the dialog displays the available user tokens: “PolicyId”, “TokenType”, and “SecurityPolice” For the selected end point, clicking “Apply” will apply the security settings “SecurityMode” and “SecurityPolicy” on the “Communication” tab in the “Security” section.

“Security”
“Messages Security Mode”	Type of ⮫ encryption “None”: No encryption and no signing Note: if you select this option, there can be no guarantee who receives the data. Therefore, “None” should be used exclusively in closed networks. “Sign and Encrypt”: The transferred data will be signed and encrypted. Signing makes sure that the data is not manipulated and the receiver is correct. “Sign”: The transferred data will be signed. Signing and encryption work only for certificates.
“Security Policy”	List box for the encryption method to be used: Basic256sha256 Requirement: Either “Sign and Encrypt” or “Sign” was selected for “Messages Security Mode”.
“Client certificate”	Here you can specify a certificate for an encrypted signed access to the OPC UA Server for the purpose of browsing. NOTE: The access which is safeguarded in this way is ONLY for browsing the server (see above, “Browse Live Server” option). For encrypted data exchange between the server and client in online mode, a separate certificate is required, which can be created in the security screen. For more information see: ⮫ Further information, ⮫ “Creating a project for OPC UA access with the existing symbol configuration ”, ⮫ “Configuration and commissioning of the OPC UA Server ”, ⮫ “OPC UA Server ”, ⮫ “Specification-compliant configuration of the OPC UA Server ”, ⮫ “Setting up an encrypted connection with the "UaExpert" client ”, ⮫ “User management in OPC UA ”, ⮫ “Using the OPC UA Client to change a variable ”, ⮫ “Using events or alarms in the CODESYS project ”, ⮫ “Observing an event via the "UaExpert" OPC UA Client ”, Creating a certificate of the CODESYS OPC UA Server. In case a certificate is not available for selection, you can click the button to open the “Create Self-Signed Certificate” dialog. Here you define a password for your private key and a file name for the certificate. When you click “OK”, the certificate files `‎.cer‎` and `‎.pfx‎` are created in the project directory and the certificate is automatically registered in the certificate manager.

“Authentication”
“Anonymous”	Access without authentication. Permission for this can be granted for compatibility reasons in the “Change Communication Policy” dialog on the “Communication Settings” tab of the device editor.
“User name”	Access to the OPC UA Server requires the entry of a user name and password. You can programmatically set up how the transfer of this authentication data should be done: To help with the creation of a POU for this purpose in the project, you can click the “Create Authentification Provider” button to create a program template `‎Datasource_OPCUA_Initializer‎` and program it accordingly.