Category Archives: Communication Protocols

IEC 61158-2 Physical Layer Explained: Media, Signaling & Deterministic Communication

IEC 61158-2 defines the physical layer specification for industrial fieldbus communication systems. It establishes the electrical, optical, and timing rules that allow deterministic data transmission between industrial devices. While IEC 61158-1 defines the architecture of the standard,IEC 61158-2 defines how bits physically travel across copper and fiber media. This article explains the IEC 61158-2 physical layer in clear,… Read More »

IEC 61158 Explained: Fieldbus Standard Architecture & OSI Model Guide

If you work in industrial automation, PLC integration, or SCADA system design, you will eventually encounter IEC 61158. But IEC 61158 is not a single protocol. It is a family of international standards that define how industrial fieldbus communication systems are structured — from the physical wiring all the way up to the application layer. This article explains… Read More »

Modbus Troubleshooting in SCADA — 15 Real Field Problems Engineers Face

Modbus is simple, but real SCADA integration is rarely simple. In power systems, automation, and industrial plants, most commissioning delays come from small configuration mistakes or physical-layer issues — not from the protocol itself. This guide explains 15 real Modbus problems engineers face on site, how to recognize them quickly, and what practical actions solve them. The explanations… Read More »

IEC 61850-3 Ethernet Switch: Requirements, Features, and Substation Use

Ethernet is the backbone of modern substation automation. Protection relays, bay controllers, merging units, and SCADA gateways all communicate over Ethernet networks carrying time-critical GOOSE messages, Sampled Values, and MMS traffic. But substations are among the harshest environments for communication equipment. High electromagnetic interference, wide temperature swings, vibration, and electrical transients are the norm. A commercial office switch… Read More »

IEC 61850 MMS Port Number Explained: Why TCP Port 102 Is Used

IEC 61850 has become the global standard for substation communication systems, enabling interoperability between protection relays, bay controllers, SCADA systems, and engineering tools. At the heart of IEC 61850 client/server communication is MMS (Manufacturing Message Specification)—and one of the most searched questions is: What port number does IEC 61850 MMS use? This article provides a complete explanation of… Read More »

IEC 60870-5-104 Port Numbers Explained: TCP 2404, TLS 19998, and Firewall Configuration

IEC 60870-5-104 runs over TCP/IP. The port number defines where the controlled station (RTU or IED) listens for incoming connections from the controlling station (SCADA master). Two ports are used in practice: Getting the port wrong means no connection. Leaving it unprotected means your SCADA system is exposed. This guide covers everything about IEC 104 ports — from… Read More »

IEC 61850 Control Models Explained (Direct, SBO, SBOwES)

IEC 61850 does not treat control operations as simple “write a value and hope it works.” Instead, it defines formal control models that describe how a command is issued, who is allowed to issue it, and how safety is guaranteed. These control models are one of the most important — and most misunderstood — parts of IEC 61850.… Read More »

DNP3 Event Classes Explained: How Class 0, 1, 2, and 3 Really Work in SCADA Systems

DNP3 (Distributed Network Protocol) is widely used in power systems, water utilities, and industrial SCADA systems. One of its most misunderstood features is the event class system. Many engineers assume that Class 1, 2, and 3 represent fixed priorities defined by the protocol. In reality, DNP3 works differently. This article explains what DNP3 event classes really are, how… Read More »

IEC 60870-5-104 Security Explained: TLS, IEC 62351 & IEC/TS 60870-5-7 Guide

IEC 60870-5-104 (IEC-104) is one of the most widely used telecontrol protocols in electrical power systems. It plays a central role in communication between substations, RTUs, and control centers, especially in transmission and distribution SCADA systems. IEC-104 is reliable, efficient, and well understood by utilities worldwide. However, when the protocol was originally designed, cybersecurity was not a primary… Read More »

IEC 61850 Data Types Explained: The Complete Practical Guide

Everything engineers need to know about Basic Types, Common Data Classes, and how they appear in GOOSE, Sampled Values, MMS, and SCL. IEC 61850 is much more than a communication protocol—it is a semantic language designed to describe protection, control, measurement, and automation inside modern substations. At the core of this language lies one essential concept: 👉 Every… Read More »