An IIoT project does not become robust simply because a PLC is connected to the cloud. The architecture must preserve deterministic control, isolate external dependencies, and define what happens when the network is unavailable. ...
When a PLC must exchange data with an IT system, two common choices are REST API and MQTT. They are not competing versions of the same protocol. They represent different communication patterns. ...
OPC UA is often introduced as a way to read PLC tags from another system. That description is technically correct but incomplete. The real value of OPC UA is the ability to publish structured information about equipment, its state, and the meaning of its data. ...
The first version of a PLC application is often built around the current machine. The next machine, firmware update, or customer request exposes whether the software was designed as a reusable system or as a collection of fixed values. ...
Industrial controllers do not execute a PLC application as one large block. CODESYS organizes the application into devices, applications, tasks, and programs. Understanding that execution model is the starting point for building a predictable and maintainable controller. ...