The I/A SCADA system is a large SCADA system developed by INVENSYS FOXBORO. I/A SCADA adopts a modular and object-oriented design, following open international standards, and the SCADA server is based on the Solaris platform with a 64-bit kernel. I/A SCADA is mainly used in remote scheduling and monitoring systems of oil, natural gas, water conservancy, electric power, rail transit and other industries. The system can be based on the needs of different users to determine the scale of the system, from a single workstation to the wide distribution of thousands of workstations can be flexibly configured, the communication media used is very wide, including cable, optical cable, radio station, microwave, satellite VSAT, PSTN, DDN, ISDN, GPRS, CDMA, carrier power line, etc. The system has a high degree of dispersion, reliability, scalability and availability.

I/A SCADA system architecture
The main architecture of the I/A SCADA system is a redundant dual Ethernet architecture based on TCP/IP. Due to the modular design of the software system, all the functions of the system can be distributed in each server and function station, but also can be centrally placed on a server, which provides a very flexible scheme for the configuration and expansion of the system.

The I/A SCADA system consists of the following subsystems
1. Core SCADA subsystem
2. Preprocessing subsystem (FEP)
3. Database subsystem
4. Computing subsystem
5. History subsystem
6. Man-machine interface subsystem
7. Configuration device

System configurations vary with systems of different sizes. For example:
For large SCADA systems, at least two redundant SCADA servers and multiple functional stations should be set up. In some applications, multi-level control centers are also set up. Such as the general control center and regional control center, backup dispatching center and so on.
For medium SCADA systems, at least one SCADA server and one function station should be set up

I/A SCADA system functions
1. Core SCADA subsystem
The core SCADA subsystem is the foundation of the whole I/A SCADA system. It converts the original data into the object database required by the I/A SCADA system, and releases the object data to the alarm group, the event group, the man-machine interface, the computing subsystem or other advanced applications. The core SCADA ensures control reliability and security, and all I/A SCADA subsystems are connected together through the core SCADA subsystem.

2. Preprocessing subsystem (FEP)
The FEP subsystem is responsible for reliable data and control information exchange with all remote devices (Rtus, IEDs, PLCS, etc.), especially in the case of communication equipment failure, communication line failure, communication error rate is too high to optimize the selection of communication links. The FEP subsystem is A distributed module that can be located away from the rest of the I/A SCADA subsystem and provides flexible multi-protocol configuration and management. Physical communication interfaces include
The & # 61548; · Communication line Server (CLS)
The & # 61548; ·Terminal Server
The & # 61548; · Direct TCP/IP communication

The FEP subsystem supports the following communication protocols
The & # 61548; · DNP3
The & # 61548; ·IEC 60870-5-101
The & # 61548; ·Conitel (2025,2020 and C300)
The & # 61548; Modbus,

The FEP subsystem coordinates all kinds of data communication
The & # 61548; · Collect field data periodically, continuously or on command
The & # 61548; · Receive SOEs, events and other data with millisecond time flags
The & # 61548; · Receive DNP3 data of “report on every change”
The & # 61548; · Security logic of control command execution of “Check-before-operation”
The & # 61548; · Control the comparison of output values with field read back values
The & # 61548; · Millisecond time synchronization between master and slave stations

The FEP subsystem performs the following communication management functions
The & # 61548; · Health status detection of complete communication links between master and slave stations (including faulty links and links not currently in use)
The & # 61548; · Provide statistics on link utilization and error incidence
The & # 61548; · Manual switching of communication links is allowed
The & # 61548; · Automatically switch to the standby link when the communication link quality deteriorates
The & # 61548; · When the communication quality of the communication link with higher priority is improved, the working link will be automatically switched back
The & # 61548; · Partial link switching function

Communication Line servers (CLS) are a good choice when dealing with serial communications. It can implement remote measurement and remote control of redundant physical paths, seamless online switching, can meet the needs of different communication networks, different communication media, and provide a variety of communication protocols.

3. Database subsystem
The I/A SCADA database is built on the VERSANT Object database management system, which is specifically designed for multi-user decentralized applications and uses a uniform object-based architecture, thus providing high availability of the system. Distributed real-time databases provide built-in fault tolerance in a prioritized manner, allowing redundant data objects to be configured on multiple servers/workstations. The I/A SCADA system supports multiple concurrent database instances, allowing multiple instances to be run, simulated, tested, and developed simultaneously.

I/A SCADA databases provide the functionality of a relational database management system, but eliminate relational joins (which are the biggest problem affecting relational database performance) in a relational database, thus achieving highly real-time system performance. The database can scale to 1,000,000 objects, providing high reliability, flexibility, and availability under continuous operation conditions. Data from the I/A SCADA database can also be mapped to the ORACLE database in real time.

4. Man-machine Interface subsystem (HMI)
HMI provides an intuitive, clear interface for operating the system. Each operator can have a personalized interface, meaning that all menus, action buttons, and screen layouts can be defined. For each operator, when they log into the system, they can only get their own picture of the system. The HMI subsystem can run on both UNIX and Windows XP stations, and supports multiple CRTS and network-based X terminal display using dual redundant LAN connections.

5. Computing subsystem
Computing subsystem can run on any server/workstation, support IEC1131-3 structured text, with full coding debugging and compilation environment. The computational subsystem can complete the conventional mathematical operations and Boolean logic operations, such as the operator input short control program, switch switching program, etc. The computing subsystem generates portable computations that are text-only and do not include system connection information, which can be replicated by other IEC1131-3 compatible applications. Calculations can be triggered by state changes in numbers, either periodically or manually by the operator. The computation program supports sequence control.

The computing subsystem also provides redundancy for active computers in the form of priority order, that is, redundant backup computers are automatically activated when the currently active main computers are unable to run. Redundant schemes can be configured as 1 to 2, 1 to 3, etc.

6. Historical subsystem
History subsystem is A part of I/A SCADA distributed object database, including the storage of history data and operation events. The history subsystem collects data from the ODBMS (Object Database Management System) and can process the data through the short term, long term, and archive history modules. Time-stamped data is automatically inserted into the appropriate location in the history database. The historical data is stored continuously by incremental compression of analog and digital quantities, except for the historical data before and after the pre-defined interference trigger. Incremental compression, combined with ODBMS, allows data to be stored 2-3 times faster and retrieved faster than traditional RDBMSS (relational database management systems).

7. Configuration device
A configurator is an engineer’s tool for maintaining an I/A SCADA system. It supports fully graphical input/output of measurement and editing data. The configurator is integrated with the I/A SCADA object database and has built-in versioning for multiple databases. The graphical interface of the configurator supports all system definitions, including configuration I/A SCADA workstation capabilities, and provides system installation and database testing capabilities. Configurator is a complete set of tools to manage the database, it acts on the object database, to a series of logical screen to display, edit the system and equipment information, from the system screen can activate the database table to edit the selected object data characteristics. The configurator can generate and manage multiple databases.

I/A SCADA system characteristics
The & # 61548; · Object-oriented database engine
· Scale variability
· Modular design
· Interoperability
· Operator interface
· Dynamic communication protocol support
The & # 61548; · Optimized data access
The & # 61548; · Standards-based computer and control engine
The & # 61548; · Application development
· Configuration