Timers and Counters in Structured Text (ST) in CODESYS V3.5

Timers and Counters in Structured Text (ST) in CODESYS V3.5

Educational and Practical Handbook. 50 Ready-to-Use Solutions for Industrial Automation.

This is a practical guide for PLC programmers who work with CODESYS V3.5 and want to build reliable timers, counters, and time trackers in Structured Text. The book bridges the gap between the standard Standard.library and real-world industrial automation tasks: it shows where TON, TOF, TP, CTU, and CTUD fail, and offers proven workarounds.

What´s inside:

PLC time model, TIME and LTIME data types, task jitter;

the problem of 32-bit timer overflow after 49.7 days and safe difference arithmetic;

50 function blocks: pausable, dynamic, and retentive timers; debounce and glitch filters; watchdog timers; PWM for solid-state relays; pulse and pseudo-random generators; 64-bit counters; quadrature decoders; hour meters and resource counters; OEE time trackers; cam controllers; network heartbeats; flow meters, phase shift meters, and actuator response time meters;

each solution follows a unified structure: problem statement → interface specification → ST code → logic analysis → notes and limitations;

7 chapters, appendices with a time data type table and a safe arithmetic template.

Target audience:
PLC programmers, commissioning engineers, service engineers, students, and teachers of technical specialties.

Additional information:

Format: PDF

Language: Russian. Code is in Structured Text (ST) within the CODESYS V3.5 environment.

Scope: 7 chapters, 50 function blocks, 3 appendices, review questions after each chapter.

Structure of each solution: problem statement → interface specification (input/output table) → software implementation in ST → analysis of algorithmic logic → application notes and limitations.

Practical value: The book does not just provide code, but explains why standard blocks TON, TOF, TP, CTU, CTUD fail under specific conditions and offers workarounds. Special attention is paid to protection against TIME() overflow after 49.7 days, loss of REAL precision, overflow of 16-bit counters, and the specifics of retentive memory.