The Role of SCADA in Modern Industrial Control Systems

Introduction to Industrial Control Systems (ICS)

Industrial Control Systems (ICS) consist of various types of control systems used in industrial production, including SCADA systems, Distributed Control Systems (DCS), and Programmable Logic Controllers (PLC).

Overview Of Industrial Control System

What is SCADA

SCADA means supervisory control and data acquisition, a software system that is used to control, monitor and analyzing industrial process.
SCADA is a specific type of ICS and typically includes Human-Machine Interfaces (HMI), communication infrastructure, RTUs, and PLCs.

Who uses SCADA

SCADA systems are used by industrial organizations and companies in public and private sectors. SCADA systems are the backbone of many modern industries, including:

• Energy

• Oil and Gas

• Transportation

• Power

• Food & Beverage

• Water & Wastewater

• Manufacturing

• Recycling and many more

A Basic SCADA Diagram

PLCs or RTUs collect data(temperature, pressure or flow rate) automatically from sensors or through manual input and then feed this data to the control centre, where HMI presents the data to operators, often in graphical form, allowing them to monitor the processes. As you can see in the following diagram, PLCs and RTUs are connected to the control centre through various communication methods, including satellites, cellular networks, or power lines.

How SCADA Systems Work

The SCADA system starts by communicating in real time with controllers that are running the actual processes. These controllers include Programmable Logic Controllers (PLCs) and Remote Terminal Units (RTUs).
SCADA systems gather real-time information from these controllers and display it using a Graphical User Interface (GUI) for operators who are managing the processes in the control centre. This allows operators to respond appropriately to the process activities and create alarms when necessary.

The above diagram consists of three main parts:

1. CONTROL CENTER

   HMI (Human Machine Interface):
   This is where operators interact with the system, viewing data and sending control commands.
   Engineering Workstations:
   Used for system configuration, programming, and data analysis.
   Control Server (SCADA - MTU):
   The heart of the SCADA system. It collects data from the field devices, processes it, and executes control commands.
   Data Historian:
   Stores historical data for later analysis and reporting.
   Communications Routers:
   Connect the control centre to the wide area network (WAN).

2. Wide Area Network (WAN)

   Various communication methods:
   This connects the control centre to field sites. Some common methods include satellite, cellular etc.

3. Field Sites (Site 1, 2, and 3)

   Remote Terminal Units (RTUs):
   These are placed at the field equipment (e.g., pumps, valves, sensors) and collect data.
   Programmable Logic Controllers (PLCs):
   Used for automating field processes and controlling equipment.
   Modem:
   Provides a communication link between field sites and the WAN.
   WAN Card: Enables the field site to connect to the WAN.

Protocols and Services Used in SCADA Systems

• Modbus: Master/Slave-port 502

• BACnet: Master/Slave-port 47808

• DNP3: Master/Slave-port 19999 when using TLS, and port 20000 when not using TLS

• IEEE 802.x-Peer to Peer

• ZigBee-Peer to Peer