General functionality
- Last UpdatedApr 24, 2025
- 2 minute read
The AVEVA Enterprise SCADA system consists of three main subsystems: RealTime service, easy eXtended Operator Station (ezXOS), and Historical service.
RealTime Service
This service provides a RealTime database (RTDB) and program package that collects data, checks for alarm conditions, scales values, drives devices, provides storage space for holding current information, and provides processes to enable you to send out commands to field devices.
The RealTime service communicates with the Remote Terminal Units (RTUs) or Programmable Logic Controllers (PLCs), transmitting commands and gathering current system information.
easy eXtended Operator Station (ezXOS)
The easy eXtended Operator Station (ezXOS) subsystem provides the system displays and windows that appear to the Controllers on the monitor screen. EzXOS lets Controllers and other authorized personnel interact with the other components of the system using a Graphical User Interface (GUI). The ezXOS system includes computers that typically have a mouse-controlled command interface.
Historical Service
The Historical subsystem provides the storage space, Historical database (HDB) (a relational database) for Historical data, as well as the capacity for creating reports from this information. Historical service is connected to RealTime service for information transfer from the RealTime and into the Historical system. For more information, refer to the Historical Administrator documentation.
Other AVEVA Enterprise SCADA Components
The following table describes additional components within the AVEVA Enterprise SCADA system.
|
Component |
Description |
|---|---|
|
Test and Development System |
The Test and Development System is used for ezXOS display development, offline RealTime configuration, and is the location of any custom software development and extensions to the baseline software that enhances the system’s functionality. This system contains the RealTime and Historical services. |
|
DES |
The Display Edit Station (DES) is used for ezXOS display development. The Test and Development System is also used for display development, but the DES subsystem provides additional stations from which display development is possible. The system always includes a Test and Development System; however, it may or may not include the DES. Except for the ability to develop ezXOS displays, a DES does not possess the other functions of the Test and Development System. |
|
Redundant Hosts |
The system is managed and operated from a main control station, which functions as the central data storage and control center. Many installations also include a secondary host(s) that provide(s) Standby services at the site, or off-site services that serve as backup in the event of a disaster or maintenance at the primary site. The Standby and off-site services take control of the system when the controlling station requires off-line maintenance or fails to operate. |
|
Other Hardware Devices |
In addition to the SCADA servers, several hardware devices support the system, including operator workstation computers, RTUs, PLCs, field sensors, and network equipment. Controller computers can be located at the main control site as well as at remote locations. RTUs or PLCs are typically used for data acquisition and control at remote sites. |