What is Structured Text?
Structured Text (ST) is one of five IEC 61131-3 PLC programming languages. Unlike Ladder Logic which is graphical, ST is text-based — similar to Pascal or Python. It is the most powerful PLC language, handling complex calculations, data manipulation, and communication protocols. Most importantly, AI tools generate ST far more accurately than any other PLC language.
Why Learn ST in 2026?
AI tools like ChatGPT and Claude write excellent ST code. Modern PLCs from Beckhoff, CODESYS, and B&R use ST as primary language. It is closest to traditional programming, making skills transferable. Industry 4.0 projects rely heavily on ST for data handling and complex logic.
Basic Syntax
Variables: BOOL for on/off, INT for whole numbers, REAL for decimals, TIME for durations, STRING for text. IF-THEN-ELSE for decisions. CASE for state machines. FOR loops for repeating. TON timer for delays. CTU counter for counting.
Example: Motor with Temperature Protection
IF StartButton AND NOT StopButton AND Temperature less than 80 THEN Motor true and RunningLight true. ELSIF StopButton OR Temperature 80 or above THEN Motor false. IF Temperature 80 or above THEN OverheatAlarm true. This is readable English-like code that any engineer can understand.
Where to Practice Free
CODESYS (free, codesys.com) with built-in simulation. OpenPLC Editor (free, open source) for all IEC 61131-3 languages. Both run on your laptop without PLC hardware.
Is ST harder than Ladder Logic?
Different, not harder. Electricians prefer LD. Engineers with any programming exposure prefer ST. Both achieve the same results.
Which language do employers prefer?
In India, LD is most common. But ST knowledge increasingly required for Industry 4.0 and AI-assisted development.
Learn at ABC CAD and IT Trainings
ABC CAD and IT Trainings offers comprehensive courses across five centres in Maharashtra — Osmanpura, CIDCO, Wagholi, Hadapsar, and Sangli. With 11 years of training excellence and over 2000 students trained, we provide hands-on, industry-relevant education using 100 percent free tools. Visit abctrainings.in or call to enrol today.
