SCADA Protocols - Decode. Analyze. Master Industrial Protocols.

MQTT Broker Redundancy and High Availability: Complete Guide

Once your MQTT deployment matters — because it carries production telemetry, or controls physical equipment, or supports customers who expect uptime — a single broker becomes a liability. If that one broker fails, the entire system stops moving messages. For deployments where this is unacceptable, you need redundancy: multiple brokers configured so that the failure of any single… Read More: MQTT Broker Redundancy and High Availability: Complete Guide »

Modbus TCP on CODESYS PLCs: Step-by-Step Configuration

CODESYS is the runtime that powers a large chunk of the industrial PLC market — WAGO, Phoenix Contact, ABB, Delta, Eaton, Bosch Rexroth, Turck, and many more all use CODESYS underneath their own branded engineering software. The good news for anyone working with Modbus TCP on these platforms: CODESYS has native Modbus TCP support built in. No third-party… Read More: Modbus TCP on CODESYS PLCs: Step-by-Step Configuration »

IEC 61131-3: The Complete Guide to PLC Programming Languages

Every PLC vendor has its own toolchain, but they largely follow the same programming model. That’s because of IEC 61131-3. It defines the programming languages, the data types, and the software architecture that PLCs and their programming tools are built around. The goal is portability — write logic against the standard, and it should carry across platforms with… Read More: IEC 61131-3: The Complete Guide to PLC Programming Languages »

Modbus TCP on Allen-Bradley ControlLogix (Studio 5000)

You have a ControlLogix PLC and someone just added a Modbus TCP flow meter to your project. Studio 5000 opens, you look for the “Modbus TCP” option in the module tree… and it is not there. Not in the standard modules. Not in the add-on profiles. Not in the Ethernet configuration. That is because ControlLogix has no native… Read More: Modbus TCP on Allen-Bradley ControlLogix (Studio 5000) »

Modbus to MQTT: How the Gateway Bridge Works

Modbus and MQTT solve the same problem from opposite ends. Modbus reads and writes numbers in a device. MQTT moves messages between systems. Put them together and you can take a register sitting inside a serial meter and land its value in a cloud database a continent away. But the two don’t connect on their own — they… Read More: Modbus to MQTT: How the Gateway Bridge Works »

What Is Sparkplug B? A Complete Guide to MQTT for Industrial IoT

MQTT is deliberately unopinionated about what your payloads contain, how you structure your topics, or how devices announce themselves to the network. That flexibility is a big part of why MQTT is popular. It is also the reason MQTT alone is not enough for industrial IoT, where two vendors’ devices need to interoperate on the same broker, where… Read More: What Is Sparkplug B? A Complete Guide to MQTT for… »

Python MQTT: Complete Guide to paho-mqtt 2.x

If you write Python and you need to move small messages between devices or services, MQTT is usually the right fit. It is a publish/subscribe protocol: a client sends a message to a topic, a broker holds the connections, and every client subscribed to that topic gets a copy. Publishers and subscribers never talk to each other directly.… Read More: Python MQTT: Complete Guide to paho-mqtt 2.x »

XON and XOFF: Software Flow Control Explained

XON and XOFF are two control characters that let a serial receiver tell a sender to pause and resume. That’s the whole idea behind software flow control. No handshake wires, no dedicated signals — just two bytes sent back up the same link the data travels on. When a device can’t keep up, it sends XOFF and the… Read More: XON and XOFF: Software Flow Control Explained »

Null Modem Cable Pinout: DB9 & DB25 Wiring Reference

A null modem cable connects two DTE devices directly — two PCs, a PC and a controller console port, two pieces of test gear — with no modem in between. The whole job lives in the wiring. Transmit on one end has to reach receive on the other, and depending on the device, a few control lines have… Read More: Null Modem Cable Pinout: DB9 & DB25 Wiring Reference »

Modbus Parity and Character Format

On a Modbus serial line, every byte you send is wrapped in a few extra bits before it hits the wire. Those extra bits — the start bit, an optional parity bit, and one or two stop bits — make up the character format. Get them wrong on one device and it won’t talk to the rest of… Read More: Modbus Parity and Character Format »