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 »
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-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 (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 »
Modern critical infrastructure systems — such as electric utilities, water treatment, and oil & gas networks — rely heavily on SCADA communications to monitor and control field equipment. One of the most trusted communication standards enabling this exchange is the Distributed Network Protocol version 3 (DNP3). While DNP3 was originally designed for reliability and efficiency, its early versions… Read More »
In Distributed Network Protocol (DNP3), the Internal Indications field—commonly known as IIN—plays a fundamental role in real-time SCADA diagnostics. Whether you’re troubleshooting substation RTUs, assessing communication integrity, or analyzing unsolicited events, DNP3 IIN bits provide the device’s internal status and operational health. This article explains DNP3 IIN bits in depth, their function in DNP3, how Wireshark displays them,… Read More »
Wireshark is the go-to tool for analyzing communication protocols — and it fully supports IEC 60870-5-104 (commonly known as IEC 104). Whether you’re diagnosing network issues, validating SCADA data, or learning how IEC 104 works, Wireshark provides an unmatched level of visibility into the protocol’s Ethernet, TCP, and ASDU layers. This guide shows you how to capture, decode,… Read More »
The IEC 60870-5-104 (IEC 104) protocol is one of the most important standards for modern SCADA and telecontrol systems.It extends the earlier IEC 60870-5-101 serial protocol by enabling communication over Ethernet and TCP/IP networks, allowing utilities and industries to operate over LAN, WAN, or even public IP networks with reliability and scalability. This article explains — in plain… Read More »
Modern SCADA systems are no longer isolated. With the rise of remote substations, cloud monitoring, and IP-based protocols like IEC 60870-5-104, the traditional “trusted internal network” model is obsolete. That’s where Zero-Trust Architecture (ZTA) comes in — a cybersecurity framework that assumes no device, user, or network is inherently trustworthy.Instead, every connection must be verified, authenticated, and continuously… Read More »
Reliable communication in IEC 60870-5-104 depends heavily on properly tuned timeout parameters. The standard defines several timing constants — t0, t1, t2, and t3 — which control connection setup, data acknowledgment, and link supervision between the controlling station (master) and the controlled station (slave/RTU). Misconfigured timeouts can cause link resets, delayed data updates, or even total communication failure.… Read More »