Once a client has connected to a broker, almost everything it does comes down to three operations: publishing messages, subscribing to topics, and unsubscribing from them. Each operation has its own control packet, and most are confirmed by an acknowledgement packet from the broker. Understanding the fields these packets carry, and the acknowledgements they trigger, is what lets… Read More »
Every MQTT system is built from two kinds of participant: clients and a broker. A client is any device that speaks MQTT; the broker is the central hub that every message passes through. Before any messages can flow, a client must establish a connection to the broker, and that handshake, the CONNECT and CONNACK exchange, carries the settings… Read More »
The single most important idea in MQTT is that clients do not talk to each other directly. They talk through an intermediary, and they do so using a messaging pattern called publish/subscribe, almost always shortened to pub/sub. Every other feature of the protocol, from Quality of Service to retained messages to shared subscriptions, is built on top of… Read More »
MQTT is a lightweight, publish/subscribe network protocol that transports messages between devices. It was built to move small amounts of data across networks where bandwidth is limited, latency is variable, and connections drop without warning. Those constraints, first encountered on remote industrial sites, are exactly the conditions found across the modern Internet of Things, which is why MQTT… Read More »
If you have ever opened Wireshark on a network with Siemens PLCs, you have seen S7comm. It is the language Siemens controllers use to talk to TIA Portal, to WinCC, to SCADA front-ends, and to each other. The protocol has been around since 1994 and it is still the default way to move data in and out of… Read More »
Industrial control systems run the infrastructure that keeps modern life working — electricity, clean water, fuel, food production, and manufacturing. These systems were built for reliability, not for cybersecurity. Most of them use protocols with no authentication, run on operating systems that stopped receiving patches years ago, and sit on networks that were never meant to face external… Read More »
A complete reference for substation engineers comparing the IEC 61850 process bus and station bus — what each bus does, protocols used, hardware requirements, time synchronization needs, redundancy strategies, bandwidth, topology, and procurement considerations Quick Comparison Table Aspect Process Bus Station Bus Purpose Real-time measurement + trip SCADA, configuration, supervisory Replaces Analog CT/VT wiring + binary trips Conventional… Read More »
PROFINET defines three Conformance Classes — CC-A, CC-B, and CC-C — that determine what a device can do. CC-A handles basic real-time communication. CC-B adds network diagnostics and topology discovery. CC-C adds Isochronous Real-Time (IRT) — the hardware-scheduled, sub-microsecond-jitter communication required for motion control, synchronized drives, and time-critical process control. CC-C cannot be implemented with standard Ethernet hardware.… Read More »
Digital substations require time synchronization accurate to better than 1 microsecond. Sampled Values, GOOSE, sequence-of-events recording, traveling-wave fault location, and synchrophasor measurements all rely on precise time across the entire substation network. Standard IEEE 1588v2 (PTP) is powerful but too flexible — it has dozens of options and many possible configurations. To get interoperable, reliable, sub-microsecond timing in… Read More »
A complete reference for substation engineers covering Merging Units — IEC 61869-9 specification, processing delay limits, sample rates, variant codes, SmpSynch values, conformance classes, holdover mode, PTP/1PPS synchronization, procurement template, and field troubleshooting Quick Reference Item Value What it does Digitizes CT/VT signals and publishes Sampled Values on the process bus Standard IEC 61869-9:2016 (replaces 9-2LE guideline) Transport… Read More »