Sign In >>

5 Programming Languages

5 Programming Languages

5 Programming Languages of IEC 6-1131/3 Standard

IEC 6-1131/3 5 programming languagesTRACE MODE 6 programming tools for control systems and business-applications development target the engineers with different skills and professions. TRACE MODE 6, features five programming languages as follows: Techno SFC, Techno LD, Techno FBD, Techno ST, and Techno IL. These languages are extensions to the following IEC 6-1131/3 standard languages:

  • SFC (Sequential Function Chart);
  • LD (Ladder Diagram); 
  • FBD (Function Block Diagram);
  • ST (Structured Text);
  • IL (Instruction List).

The TRACE MODE® 6 IEC 6-1131/3 programming languages include 3 visual languages, (FBD, SFC, LD), aimed to engineers and business-analysts and 2 procedural (ST, IL), programmers-oriented languages. Using the TRACE MODE® 6 IEC 6-1131/3  languages, one can program controllers, HMI algorithms, EAM and MES logics with equal convenience.

The TRACE MODE® 6 IEC 6-1131/3 languages combine sufficient functionality, ease of use and exclude majority of errors, which occur frequently while using ordinary programming languages. The TRACE MODE® 6 version of IEC 6-1131/3  programming languages not only fully complies with requirements of standard, but also contents additional features such as extended number of functional block libraries with  typical control algorithms.

All 5 IEC 6-1131/3 programming languages have the unitary mechanism of communication with the TRACE MODE® 6 real time database. Each program has a set of arguments. The real time data enter the program through input arguments, and the results of calculations are returned in output arguments. The arguments are linked with TRACE MODE 6 channels attributes e.g. with real inputs and outputs of controllers and I/O devices, cells of databases, or with internal variables. Thus the same program can be called many times during one cycle for different data threads processing.

Programming and debugging of programs written in IEC 6-1131/3 languages is performed in the TRACE MODE 6  integrated development environment. The programs in Techno FBD, Techno LD and Techno SFC languages are written and debugged in the visual editors, and Techno ST and Techno IL represent more traditional procedural languages, programmed in the text editors. The IEC 6-1131/3 standard programs written in different languages can interact with each other. For example, a program written in Techno FBD can call a functional block written in Techno ST language, and within such block, a subprogram written in Techno LD can be called, etc. Such flexibility in programming allows programmers, control engineers and business-consultants to work efficiently on the project, while each of them performs his part of the job using the most convenient programming tool.

Brief Description of Programming Languages

  • The Techno FBD language is aimed to control engineers. It would be difficult to find more easy language for programming of PID-loops. A program written in Techno FBD represents a diagram consisting of a set of functional blocks connected between each other via inputs and outputs.

Over 150 standard functional blocks, implementing wide range of functions – from simplest logic operations to adaptive self tuning PID-loop regulator are included in the TRACE MODE® 6. Filtration, PID, PDD, modal, fuzzy, positional control, PWM-transformation, statistical, trigonometric, as well as integrated ready-to-use control algorithms for valve, pump, motor – all this is implemented as standard FBD-blocks in TRACE MODE® 6.

This training video shows how to program logics in the ViewPAC industrial PAC-controller on FBD language.


  • The Techno LD language is for engineers familiar to compile the relay logics diagrams. The LD editor looks very much like FBD editor, but instead of functional blocks the programs are composed with "contacts" and "coils". It is possible to include ordinary FBD blocks into the program written in Techno LD, though this TRACE MODE® 6 feature fall somewhat beyond the frameworks of the  IEC 6-1131/3standard.


  • The Techno ST programming language is oriented first of all to programmers. It is a of high level programming language, similar to Pascal. It supports arrays (including multidimensional), type conversion monitoring, such constructions as DO-WHILE, REPEAT-UNTIL, FOR-TO-DO, IF-THEN-ELSE, CASE-OF are available, as well as other operators clear and intuitive to any programmer.

Header of the program is build automatically according to the list of arguments which allows to save time for programming. Service words, markers, comments and numerical constants are highlighted with color as it is adopted in the up-to-date visual programming environments. The colors’ settings are accessible to user.

  • The Techno IL programming language is the simplest language of mnemonic instructions, somewhat similar to Assembler. This language was included into the  IEC 6-1131/3 standard for programming of low end controllers. The IL programs are easily translated into machine-language code of any processor, which ensures very fast program speed. However, the up-to-date controllers have enough performance, and the Techno IL does not actually have advantages over  ST or FBD. Nevertheless, this language was included into TRACE MODE® 6 in order to support outdated equipment. This fact itself once more emphasizes advantage of the IEC 6-1131/3.


  • The Techno SFC programming language is a powerful tool of structuring of sophisticated algorithms. Per se, the SFC is not an independent language. A program written in Techno SFC looks like a block diagram composed of program blocks (steps), transitions between them, and conditions, according to which these transitions are performed. Each program block, like each condition of transition, is a program written in any IEC 6-1131/3 standard language. This language is very convenient for programming of batch processes and business-applications. The Techno SFC can be easily used by engineers, as well as by business-analysts.

The programs written in the IEC 6-1131/3 languages can be transferred into TRACE MODE 6 from any other programming platform that supports this standard.

TRACE MODE 6 compiles all 5 IEC 6-1131/3 languages programs, including SFC in machine-codes! This ensures the maximum speed of program execution in real-time.

Powerful debugging tools


Current TRACE MODE release 6.10.2. Upgrade now for free!