300+ SCADA Protocol Articles & Guides
Deep dives on Modbus, DNP3, IEC 60870-5-101/104, IEC 61850, OPC UA, Profinet, MQTT, IEC 62443, and substation automation — written for practicing engineers.
MQTT Topics and Wildcards Explained
How MQTT topics and wildcards work: topic levels, single-level (+) and multi-level (#) wildcards, $SYS topics, matching rules, and topic naming best practices.
MQTT Clients, Brokers & Connection Establishment Explained
How MQTT clients and brokers work and how a connection is established: the CONNECT and CONNACK packets, every field, return codes, NAT and keep alive.
MQTT Publish, Subscribe & Unsubscribe: Packets Explained
How MQTT publish, subscribe and unsubscribe work: the PUBLISH, SUBSCRIBE and UNSUBSCRIBE packets, every field, and the SUBACK and UNSUBACK acknowledgements.
MQTT Publish/Subscribe Pattern Explained: How Pub/Sub Works
How the MQTT publish/subscribe pattern works: decoupling, the broker's role, message filtering, scalability, and how pub/sub differs from message queues.
What Is MQTT? Protocol Architecture, Packets & How It Works
MQTT is a lightweight publish/subscribe protocol for IoT. Learn its architecture, packet structure, QoS, sessions, security and how the protocol works.
S7comm Protocol Explained: How Siemens S7 PLCs Communicate
S7comm protocol explained: how S7-300, S7-400, S7-1200, and S7-1500 talk over TCP port 102, the PDU header, ROSCTR message types, and S7comm vs S7CommPlus.
What Is ICS Security? Complete Guide to Protecting Control Systems
What is ICS security? Covers SCADA, DCS
Process Bus vs Station Bus: IEC 61850 Architecture
Process bus vs station bus in IEC 61850: which protocols run on each, time sync and hardware differences, redundancy, bandwidth, and procurement guidance.
PROFINET CC-C Requirements: IRT Ethernet Cards, ASICs, Switches
PROFINET CC-C hardware per IEC 61784-2: IRT Ethernet cards (CP 1626, cifX), certified ASICs, switch requirements, PTCP timing, and a tender checklist.
PTP Power Profile Explained (IEC/IEEE 61850-9-3)
PTP Power Profile explained: the 1 microsecond budget, grandmaster and transparent clock requirements, holdover, PRP and HSR integration, and link rules.
What Is a Merging Unit? IEC 61850 Process Bus Explained
Merging unit explained: how it digitizes CT and VT signals and publishes Sampled Values, with TCTR and TVTR modeling, SAMU vs built-in, and sample rates.
HSR Frame Structure — How the HSR Tag Works
The HSR tag is six bytes — EtherType, PathId, LSDU size, and sequence number. Here's what each field does and why it matters for the ring to work.
HSR Node Modes Explained: H, N, T, M, U and X (IEC 62439-3)
A clear breakdown of all six HSR node modes — what each one does, when to use it, and what breaks if you get it wrong. Based on IEC 62439-3.
PTP Clock Synchronization in PRP and HSR Networks
How PTP works across PRP and HSR networks — BMCA, Hybrid Clocks, correctionField, RedBox clock roles, and what the standards actually require.
How HSR Ring Sizing Affects Latency
Node count, forwarding delay, and frame size all affect HSR ring latency. Learn how to calculate worst-case delay and size your ring for IEC 61850 applications.
How to Connect PRP and HSR Networks | Step-by-Step Guide (IEC 62439-3)
How to connect PRP and HSR networks using RedBox and QuadBox. Five topology scenarios with step-by-step guidance, IP example, and rules from IEC 62439-3.
RedBox and QuadBox in PRP/HSR Networks
RedBox connects legacy devices to PRP and HSR networks. QuadBox links two HSR rings. Here's how both work, when to use them, and what the standard actually says.
Modbus TCP Mitsubishi iQ-R: GX Works3 Setup Guide
Modbus TCP Mitsubishi iQ-R setup in GX Works3: RJ71EN71 module parameters, MODBUS Device Assignment, float byte order, exception codes, and troubleshooting.