2. SCADA systems and their structure.

SCADA (Supervisory Control And Data Acquisition), in a general view, have the allocated architecture like represented on fig. 2. Elements of SCADA systems, in sense of the software, carry out following functions:
The acquisition server: represents a task or group of tasks engaged in data acquisition from sources of data, or act in a role as a source of data. Into tasks of a server enters:

• reception and-or formation of data;
• data processing;
• service of queries about access to data;
• service of queries about updating of data.

The server of archiving: represents a task or group of tasks engaged in archiving of data. Into tasks of the server enters:

• archiving of data of SCADA-system;
• service of queries about access to contemporary records;
• import/export of archives.

The journaling server: represents a task or group of tasks engaged in archiving of messages. Into tasks of the server enters:

• archiving of messages of units of SCADA-system;
• service of queries about access to archival messages;
• import/export of archives.

The alarm server: represents a task or group of tasks carrying out functions of the server of recording concerning a narrow category of messages of the signal system.
The operator working place: represents constantly functioning GUI (Grafical User Interface) application executed in an one-monitor, multimonitor or panel mode and carrying out functions:

• granting of the user interface for the control over a condition of technological process;
• granting of an opportunity of formation of operating influences;
• granting of an opportunity of studying and the analysis of history of technological process;
• granting of toolkit for generation of the reporting documentation.

The engineer working place: represents GUI application used for configuration of SCADA system. Into tasks of the application enters:

• granting of toolkit for manipulation with system functions of system;
• granting of toolkit of a workplace of the operator;
• granting of toolkit for manipulation with architecture of SCADA system as a whole (distribution of functions between stations, creation, removal of stations...).

The chief working place: represents GUI application, as a rule, executed in an one-monitor mode and carrying out functions:

• granting of the user interface for the control over a condition of technological process;
• granting of toolkit for studying and the analysis of history of technological process as is direct from an active server, and on the basis of separate archives;
• granting of toolkit for generation of the reporting documentation.

The technologist working place: completely includes functions of a workplace of the operator plus model of technological process (without direct communication with technological process).
The work planner working place: completely includes functions of a workplace of the technologist plus toolkit for creation of models of technological processes.