"SCADA protocols" play a crucial role in supervisory control and data acquisition (SCADA) systems, allowing efficient data exchange between various components. Here are some key protocols used in SCADA networks:

1. DNP3 (Distributed Network Protocol):

• Overview:
  • DNP3 is widely used in process automation systems, including electric utilities, chemical plants, and water distribution networks.
  • It facilitates communication between monitoring systems, data acquisition units (RTUs), and control equipment.
• Features:
  • Interoperability with related protocols like MODBUS.
  • Corresponds to layer 2 (data link layer) in the OSI model, providing features like error checking, link control, and data fragmentation.
  • Transport function (layer 4) and application layer (layer 7) for SCADA applications.
  • Improved bandwidth efficiency through event-oriented data reporting.
  • Good error detection capabilities.
• Security Considerations:
  • Originally not designed with robust security features.
  • Now compliant with IEC 62315-5, emphasizing secure SCADA-RTU master station communications.

2. IEC 60870 Protocol:

• Purpose:
  • Developed for reliable communication in electric utility automation systems.
  • Ensures information integrity and transmission under adverse conditions.
• Inter-Control Center Communications (ICCP):
  • Part of IEC 60870, used for interconnecting RTUs and IEDs (Intelligent Electronic Devices).
  • Widely used in master station communications.
• Security:
  • Security authentication is essential due to historical vulnerabilities.

3. HDLC (High-Level Data Link Control):

• Usage:
  • HDLC is a data link layer protocol used for point-to-point communication.
  • Commonly employed in SCADA networks.
• Features:
  • Provides reliable and error-checked communication.
  • Supports both balanced (full-duplex) and unbalanced (half-duplex) modes.
  • Efficient for SCADA applications.

4. Modbus:

• Open Source:
  • Modbus is widely adopted due to its open-source nature.
  • Approximately 80-90% of plant devices (inverters, trackers, etc.) use the Modbus protocol.
• Functionality:
  • Simple and efficient for transmitting data between devices.
  • Supports both serial (Modbus RTU) and Ethernet (Modbus TCP) communication.
  • Commonly used in industrial automation and SCADA systems.