MMS (Manufacturing Message Specification) is the client/server protocol used by IEC 61850 for SCADA communication, reporting, control commands, and engineering access. It runs over TCP port 102. When an IED stops reporting to SCADA, when a control command fails, or when an MMS association does not establish — Wireshark is the first tool you reach for. But decoding… Read More »
The Siemens S7-1200 has built-in Modbus TCP support. No additional communication modules are needed. The CPU handles Modbus TCP natively through its PROFINET Ethernet port. You configure it using two instruction blocks in TIA Portal: A single S7-1200 can run both roles at the same time — serving data to SCADA while polling field devices. Despite the simplicity,… Read More »
Every piece of data in an IEC 61850 system lives inside a logical node. A circuit breaker position is inside XCBR. An overcurrent trip signal is inside PTOC. A voltage measurement is inside MMXU. A GOOSE control block is inside LLN0. Logical nodes are the building blocks of the IEC 61850 data model. They represent functions — not… Read More »
Every Modbus device comes with a register map. It is usually a table in the user manual or a separate PDF that lists all the data points the device makes available — voltages, currents, setpoints, alarms, status bits, and configuration parameters. Reading a register map sounds simple. But it is one of the most common sources of errors… Read More »
If you work with SCADA systems, you know the pain. You’re on-site, staring at raw hex frames, and your laptop is back at the office. You need to decode a Modbus response or check a DNP3 unsolicited message — right now. That’s why SCADA Protocol Analyzer exists. It’s an Android app that puts a full protocol decoder in… Read More »
OPC DA was the workhorse of industrial communication for over two decades. It connected PLCs to SCADA systems, HMIs to historians, and control rooms to the factory floor. It worked. But the world changed. Linux grew. Cloud computing arrived. Cybersecurity became critical. And OPC DA — locked to Windows, with no encryption, dependent on a technology Microsoft has… Read More »
OT security is the practice of protecting operational technology — the hardware and software that monitors and controls physical processes — from cyber threats. This includes the systems that run factories, power plants, water treatment facilities, oil refineries, transportation networks, and any environment where digital commands drive physical outcomes. Operational technology is different from information technology. IT manages… Read More »
OPC UA Pub/Sub is a communication pattern within the OPC UA standard that allows data to flow from publishers to subscribers without requiring a direct connection between them. A publisher sends data to a message broker or network bus. Any number of subscribers receive that data independently. No handshake. No dedicated session. No request-response cycle. This is fundamentally… Read More »
SCADA security is the practice of protecting Supervisory Control and Data Acquisition systems from unauthorized access, tampering, and cyberattacks. SCADA systems monitor and control physical processes across large geographic areas — power grids, water pipelines, oil and gas networks, and transportation systems. These systems were never designed with cybersecurity in mind. They were built for reliability. For decades,… Read More »
Every Modbus message contains a function code. It is a single byte that tells the slave device what operation to perform — read coils, write registers, or diagnose communication. The Modbus specification defines multiple function codes, but in practice you will use about six of them for 95% of your tasks. The rest are either rarely implemented, vendor-specific,… Read More »