• Engineering server
• Runtime server
• Operator station

The Engineering server
contains the system's central engineering database. In other words, all objects that are created, configured, and assigned parameters in the "CaeManager" engineering tool are subject to semantic and syntactic review within the centralized object directory. All process control system objects are downloaded from this central engineering database to the desired target resource.

The Runtime server
represents the process control system's real-time database and contains all process values, system values, messages, and alarms. The Runtime server also coordinates the archiving of process values and events in the archive database.

The Operator station
is used to operate and monitor the system's process and display all archived data for the operator.

Download process
During a download, all objects are transferred from the central object directory (central system engineering database) to the controllers, Runtime servers, and operator stations. If the Runtime servers are designed redundantly, then a separate download takes place to both Runtime servers.