Learn what contacts, coils, latches, one-shots, counters, program-flow and data instructions do during execution. Compare representative Allen-Bradley, Siemens, IEC 61131-3 and Mitsubishi conventions, then practice the underlying logic in a browser-based training simulator.
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Watch the real browser product respond to the task on this page, then try the same practical workflow yourself. No slides, concept mockups, install, or credit card.
Try this in the browserFrom field signal to instruction result
A mnemonic only becomes useful when you can connect it to the field device, controller memory, task execution and physical result. These diagrams make that complete path visible.
Direct answers
PLC code is the executable control logic stored in a programmable logic controller. It may be written as ladder diagram, function block diagram, structured text, sequential function chart or another vendor-supported form. An instruction is one operation inside that program; the full code also includes tags, routines, tasks, data types and controller configuration.
This page is a catalog of common PLC operations. Capitalized Instruction List can also mean the legacy IEC 61131-3 textual language that writes logic as mnemonic statements. If that is what you need, use the PLC Instruction List simulator and guide.
Foundations
PLC platforms share control concepts inherited from relay logic and computing, but they do not expose one universal instruction set. Allen-Bradley's Studio 5000 uses mnemonics such as XIC, OTE and JSR. Siemens and IEC-oriented environments use graphical elements and function blocks with platform-specific details. Mitsubishi programming tools use mnemonics such as LD, OUT, SET, RST and PLS. Available instructions, parameters and runtime behavior depend on controller family and software version.
The transferable skill is predicting how Boolean state, transitions, retained values and task execution affect a machine. Comparable contacts and rising-edge detectors solve similar control problems, but they are not automatically interchangeable: storage, prescan, enable, scope and update rules can differ. Use this guide to build a mental model, then verify exact behavior in the target vendor's documentation.
Each instruction below gets its own page: what it does during the scan, a ladder diagram showing it in context, a timing diagram where behavior is stateful, the vendor naming table, two worked examples and the mistakes that actually bite people in the field. Start with contact-and-coil behavior in the no-account browser exercise; after signup, the scenario catalog covers broader instruction combinations in practical machine contexts.
The reference
Looking for timers? TON, TOF and RTO have a dedicated deep-dive on the PLC timers page, counters get the full treatment on PLC counters, and every symbol is drawn out on the ladder logic symbols reference.
Build the first contact-and-coil rung without an account, toggle a field input and observe the output. Then save your result and continue into guided scenarios that combine timers, counters, latches, data and program structure.
PLC code and example path
Read the instruction behavior, inspect a complete pattern, run its edge cases and then adapt it as a project.