SCADA Protocols - Master Every Communication Protocol

DNP3 Secure Authentication Version 6 (SAv6): Encryption and Authorization Explained

Modern SCADA and utility automation systems face growing cybersecurity demands. The Distributed Network Protocol (DNP3)—the backbone of many control networks—has evolved to meet them. With the release of IEEE 1815-2020, the DNP3 Secure Authentication Version 6 (SAv6) specification brings authenticated encryption, centralized authorization, and simplified key management directly into the protocol. This article explains how SAv6 improves on… Read More »

DNP3 Port 20000 Explained: Configuration, Security, and Best Practices

In power automation, reliable and secure data exchange between control centers and field devices is critical. One of the most adopted communication protocols that enables this is Distributed Network Protocol version 3 (DNP3). DNP3 communicates over TCP/UDP port 20000, which serves as the standard IP port for linking SCADA master stations with remote field units like RTUs and… Read More »

DNP3 Report by Exception, Background Polls, and Balanced Communication

The Distributed Network Protocol (DNP3) is recognised for its efficiency and reliability in SCADA and power automation systems. The DNP3 protocol is characterized by three key operational concepts: Report by Exception, Periodic Background Polls, and Balanced Communication. These concepts enable the system to optimize bandwidth utilization while ensuring real-time monitoring of field device status. Report by Exception (unsolicited… Read More »

Modbus over RS485 Communication Frequency | Recommended Baud Rates & Best Practices

In industrial automation, Modbus over RS-485 is still one of the most popular and reliable ways to connect programmable logic controllers (PLCs), sensors, meters, and field devices. One key parameter that determines how well this network performs is the communication frequency. this is also called the baud rate. It defines how fast data is transmitted between Modbus master… Read More »

DNP3 System Topology Explained: Master, Multidrop, and Hierarchical

In a DNP3-based SCADA system, system topology refers to the physical and logical arrangement of how master stations, outstations, and communication devices are connected and interact. Designed for flexibility and reliability, DNP3 supports multiple network configurations that can be tailored to the system size, communication medium, and redundancy requirements. The most common DNP3 topologies include master–slave, multidrop, hierarchical,… Read More »

Link Initialization in IEC 60870-5-101 | Master-Slave Communication Setup

Before any data or command exchange can begin, the communication link between the controlling station (master) and controlled stations (RTUs or substation gateways) must be properly established. This process — called link initialization — ensures both sides start from a synchronized state with correct frame sequencing, clear buffers, and ready communication paths. Link initialization is part of the… Read More »

IEC 101 Frame Formats Explained | Fixed & Variable Frames

The IEC 60870-5-101 protocol (commonly known as IEC 101) is a serial telecontrol standard widely used in SCADA, power automation, and industrial control systems. It defines how data is formatted and transmitted between a controlling station (master) and controlled stations, such as RTUs or dedicated substation operation and data-handling devices. Each message on the line is called a… Read More »

Originator Address in IEC 60870-5-101 Explained

The Originator Address in IEC 60870-5-101 is an optional but powerful feature that enhances message routing and command traceability in telecontrol and SCADA systems. This one-byte field, located within the Cause of Transmission (COT) section of the ASDU, allows a controlling station to explicitly identify itself when sending commands. In systems with a single master station, this feature… Read More »

IEC-101 vs IEC-104 — Key Differences Explained

IEC-60870-5-101 (IEC-101) and IEC-60870-5-104 (IEC-104) are two of the most important communication protocols used in electrical power systems, especially in substations and national SCADA systems. Both belong to the IEC-60870-5 family, which defines how remote telecontrol data is exchanged for monitoring, supervision, and automation. Even though the two protocols share the same information structure (ASDUs), they behave very… Read More »

DNP3 Message Structure Explained

DNP3 (Distributed Network Protocol) messages are built in multiple layers to ensure reliable communication between master stations and outstations (RTUs or IEDs) in SCADA systems. Each layer adds its own control information, creating a message that can be verified, retransmitted, and correctly interpreted across noisy or unreliable communication links. The Enhanced Performance Architecture (EPA) DNP3 follows the IEC… Read More »