Server Redundancy

The CIMPLICITY OPC UA Server detects if a project is configured for redundancy. If it is configured for redundancy:

• Generates (if they do not already exist) separate certificates for the Primary and Secondary machines. These certificates are saved in the <project>/pki/own folder and have the host name appended to the name. When the OPC UA starts, it replaces the default certificate and key with the certificate and key matching the current host.
• Updates the Server/ServerRedundancy Object. The RedundancySupport property is set to 'HOT'. The ServerUriArray property is populated with the URIs of the Primary and Secondary CIMPLICITY UA Servers. The ServerNetworkGroups  property is populated with the IP addresses for the Primary and Secondary hosts which are saved in the CimHosts file.
• Sets the ServiceLevel to 255 for the current active and 190 for the current standby. The CIMPLICITY OPC UA Server detects when the active is changed and updates the ServiceLevel to reflect the current state. Clients use this property to determine which server must be used for writes.

The OPC UA server network address needs to use [NodeName] for the primary and the secondary nodes to have different end points.

If GDS agent is used to sign OPC UA server certificate, GDS agent needs to be launched using advanced button in the OPC UA security configuration tool.