Controls
PLC Systems
Architecture, programming, analog control, communications, and troubleshooting for programmable logic controllers.
Written guides in this section
Full references, procedures, and diagnostic guides published under PLC Systems.
PLC Architecture
How a programmable logic controller is physically organized: the chassis, backplane, processor, I/O modules, remote racks, and what those choices mean for wiring, expansion, and failure.
8 min readUpdated Sep 5, 2026
The PLC Processor
What the processor module does on every scan, how its memory is organized, what the mode switch and status lights mean, and how it faults and recovers.
8 min readUpdated Sep 5, 2026
Control Power Supplies
Sizing the 24 VDC supplies that run a controller and its field devices, separating loads that should not share a supply, and keeping the controller alive through a power event.
8 min readUpdated Sep 5, 2026
PLC I/O Systems
Discrete and analog input and output modules, sinking and sourcing, relay and transistor outputs, wiring conventions, and the module diagnostics that find field faults from the panel.
9 min readUpdated Sep 5, 2026
Controller Memory and Addressing
How a controller organizes its data: data tables and tags, the input and output images, the elementary data types and what they hold, and the naming discipline that keeps a program readable years later.
8 min readUpdated Sep 5, 2026
Tasks and Execution Priority
How a controller schedules its work: the continuous task, periodic tasks at a fixed rate, event tasks triggered by something happening, how priority preempts, and where each kind of logic belongs.
7 min readUpdated Sep 5, 2026
Topics in this area
PLC Fundamentals
How a programmable logic controller is built and how it executes.
10 topics
Programming
The five IEC languages and the structures that make a program maintainable.
12 topics
Analog Control
Getting a field measurement into a controller and acting on it correctly.
8 topics
Communications
The protocols that move data between controllers, devices, and SCADA.
8 topics
Troubleshooting
Symptom-first diagnosis for a controller that is not behaving.
7 topics
Platforms
Platform-specific notes. Vendor names are used for identification only.
12 topics
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