What is SCADA?

SCADA stands for Supervisory Control and Data Acquisition.  
These systems were originally created in the 60's on mainframe and mini-computer systems.
Today the typical implementation is PLC (programmable Logic Controller) for machine control 
and computers connected to a Network for centralized data collection.  
Some examples are Inductive Automation Ignition and Wonderware

Typical Components include:

  • External access. This provides the machine connection. Physical media include serial communications (RS-232C), PC card access (AB DH+, ARCNET, Modbus Plus) or direct analog/digital I/O.  Newer connections are fieldbuses, such as DeviceNet, Profibus or Ethernet and USB
  • Process Alarming for out of tolerance conditions.
  • Data logging and reporting.  Productivity and shift reports
  • Operator interface. The operator screens are usually designed with an offline graphical editor.
  • Computation engine. This allows the package to calculate totals, averages, SPC (Statistical Process Control) summary data and any derived information from the raw data.
  • Network access. Usually packages allow remote viewing of the process from another station. This can be done using NETDDE or DCOM in Windows based packages.
  • Database access. Many packages allow direct logging and retrieval of information from a centralised database server, such as Oracle, Sybase or Microsoft SQL Server. In general Windows based packages use ODBC or ADO access.
  • Custom programming. Different packages allow different level of customisation. Some will supply C libraries, others provide custom tool sets and some just allow program triggers within the package to run another program.

Video about SCADA/DCS and network security


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