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PLCampus

Learn PLCs step by step

A structured path from what a PLC is to real-world industry practices. Every topic includes interactive diagrams and, where it makes sense, an example to try in the simulator.

Fundamentals

What a PLC is, how it works inside and which types exist.

  1. 01What is a PLC?What a programmable logic controller is, where it is used and how it differs from a relay panel or an Arduino.5 min read
  2. 02How a PLC works insideThe parts of a PLC —power supply, CPU, memory and I/O modules— and the scan cycle it repeats endlessly.5 min read
  3. 03Types of PLCProgrammable relays, compact, modular and rack PLCs, safety PLCs and PACs. What sets them apart and when to use each one.4 min read

Hardware & wiring

Inputs, outputs, wiring and communications.

  1. 04Inputs and outputsDigital and analog signals, PNP and NPN sensors, output types, actuators and why the emergency stop is wired normally closed.6 min read
  2. 05Wiring and connections24 VDC and mains supply, commons, terminal blocks, wire colours and the typical layout of a PLC control panel, with an interactive diagram of terminals and ports.4 min read
  3. 06Ports and communicationsUSB, RS-232, RS-485 and Ethernet; industrial protocols such as Modbus, PROFIBUS, PROFINET, EtherNet/IP, CC-Link, EtherCAT and OPC UA; and what an HMI and a SCADA are.4 min read

Programming

Memory, languages, instructions and good practices.

  1. 07Memory and addressingBits, bytes and words; a PLC's memory areas; internal markers; and how Siemens, Allen-Bradley, Mitsubishi, Omron, Schneider and the IEC standard name their addresses.4 min read
  2. 08IEC 61131-3 languagesLadder (LD), function block diagram (FBD), structured text (ST), instruction list (IL) and SFC, with the same example in all five languages and when each one fits.3 min read
  3. 09Basic instructionsContacts, coils, set and reset, edges, seal-in and interlocks, TON, TOF and TP timers, CTU, CTD and CTUD counters, comparisons, maths and MOVE.4 min read
  4. 10Real-world good practicesComments, variable names, program structure, fail-safe design, interlocks and why people's safety cannot depend on the PLC software alone.3 min read