Structured text

For the lightweight text markup languages, see StructuredText and reStructuredText.

Structured text, abbreviated as ST or STX, is one of the five languages supported by the IEC 61131-3 standard, designed for programmable logic controllers (PLCs).[1][2] It is a high level language that is block structured and syntactically resembles Pascal, on which it is based.[3] All of the languages share IEC61131 Common Elements. The variables and function calls are defined by the common elements so different languages within the IEC 61131-3 standard can be used in the same program.

Complex statements and nested instructions are supported:

  • Iteration loops (REPEAT-UNTIL; WHILE-DO)
  • Conditional execution (IF-THEN-ELSE; CASE)[3]
  • Functions (SQRT(), SIN())
  1. ^ Bacidore, Mike (16 May 2018). "Should I limit programming to ladder logic or use all standards within IEC 61131?". Control Design.
  2. ^ Stevic, Tom (5 May 2017). "A very short history of PLC programming platforms". Control Design.
  3. ^ a b Roos, Nieke. "Programming PLCs using Structured Text". Department of Computing Science, University of Nijmegen. CiteSeerX 10.1.1.49.2016. {{cite journal}}: Cite journal requires |journal= (help)