Dedicated standby server - no redundant I/O server

This configuration includes a dedicated standby node ready to take control of the system when the active engine is off-line (refer to the following figure).

AppEngine1 hosts all AppObjects as well as DI client objects. The I/O Server is installed on both nodes but the DI client object collects data from the node where the active engine resides.

To provide a higher degree of reliability to the system, you can implement a script in the DI client object to set the Redundancy.ForceFailoverCmd attribute in the AppEngine object to True when the connection with the PLC fails.