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Codesys (usually stylized as CODESYS, a portmanteau for controller development system, previously stylised CoDeSys) is a development environment for programming controller applications according to the international industrial standard IEC 61131-3.


CODESYS is developed and marketed by the German software company 3S-Smart Software Solutions located in the Bavarian town of Kempten. Version 1.0 was released in 1994. CODESYS licenses are free of charge and can be installed legally without copy protection on further workstations. The software tool covers different aspects of industrial automation technology with one surface.


All five programming languages for application programming defined in the IEC 61131-3 are available in the CODESYS development environment.

Additional graphical editor available in CODESYS not defined in the IEC standard:

  • CFC (Continuous Function Chart) is a sort of freehand FBD editor. Other than in the network-oriented FBD editor where the connections between inputs, operators and outputs are set automatically they have to be drawn by the programmer. All boxes can be placed freely which makes it possible to program feedback loops without interim variables.

Integrated compilers transform the application code created by CODESYS into native machine code (binary code) which is then downloaded onto the controller. The most important 16 and 32-bit CPU families are supported, such as C166, TriCore, 80x86, ARM/Cortex, PowerPC, SH, MIPS, BlackFin and more.

Once CODESYS is online, it offers an extensive debugging functionality such as variable monitoring/writing/forcing by setting breakpoints/performing single steps or recording variable values online on the controller in a ring buffer (Sampling Trace).

CODESYS V3.x is based on the so-called CODESYS Automation Platform, an automation framework device manufacturers can extend by their own plug-in modules.

The CODESYS Professional Developer Edition offers the option to add components to the tool which are subject to licensing, e.g. integrated UML support, a connection to the Apache Subversion version control system, online runtime performance analysis, static code analysis of the application code or script based automated test execution.

The CODESYS Application Composer serves to create applications by using existing modules. The user composes, parameterizes, and connects the required modules to form a complete application. This configuration does not require knowledge of PLC programming and can therefore be done by technicians without programming experience. Internal generators create complete, well-structured IEC 61131-3 applications including the I/O mapping and visualizations. The Application Composer requires a license to develop and to compose modules. Furthermore, there are freely usable modules (i.e. Persistence Manager, Device Diagnosis), which can be used without a license.


After implementing the CODESYS Control Runtime System, intelligent devices can be programmed with CODESYS. A charged-for toolkit provides this runtime system as a source and object code. It can be ported to different platforms.

Fieldbus technology[edit]

Different field busses can be used directly in the programming system CODESYS. For this purpose, the tool integrates configurators for the most common system such as PROFIBUS, CANopen, EtherCAT, PROFINET and EtherNet/IP. For some systems, additional protocol stacks are available in the form of CODESYS libraries which can be loaded subsequently. By means of a software plugin in the FDT (Field Device Tool) Frame application, additional device-specific user interfaces from third-party suppliers can be integrated. Communication between these interfaces will be realised through a communication Device Type Manager (DTM).


An integrated editor helps the user create complex visualization masks directly in the programming system CODESYS and animate them based on application variables. To simplify the procedure, integrated visualization elements are available. An optional toolkit enables the user to create his own visualization elements. The masks created are, among others, used for application tests and commissioning during online operation of the programming system. In combination with optional visualization clients, the masks can also be used to operate machines or plants, e. g. on controllers with integrated display, in web browsers or a portable runtime under Windows or Linux.


An optional modular solution for controlling complex movements with an IEC 61131-3 programmed controller is also completely integrated in the programming system CODESYS. The modular solution includes:

  • Editors for motion planning, e. g. with CAMs or DIN 66025 CNC descriptions
  • Library modules for decoder, interpolator, for program execution, e. g. according to PLCopen MotionControl, for kinematical transformations and visualization templates


To reach the safety integrity level (SIL) required after a risk analysis, all system components have to comply to this level. Pre-certified software components within CODESYS make it much easier for device manufacturers to have their controllers SIL2 or SIL3 certified. Therefore, CODESYS Safety consists of components within the programming system and the runtime system, whereas the project planning is completely integrated in the IEC 61131-3 programming environment.

Industrial usage[edit]

Over 250 device manufacturers from different industrial sectors offer intelligent automation devices with a CODESYS programming interface. Consequently, thousands of end users such as machine or plant builders around the world employ CODESYS for all sorts of automation tasks.

The CODESYS Device Directory[1] offers an overview on nearly 400 devices programmable with CODESYS from leading manufacturers from the sectors control engineering, automation components and embedded systems.

See also[edit]


  • B. Vogel-Heuser/A. Wannagat (2008) Modulares Engineering und Wiederverwendung mit CoDeSys V3, Oldenbourg Industrieverlag
  • Herbert Bernstein (2007) SPS-Workshop mit Programmierung nach IEC 61131 mit vielen praktischen Beispielen, mit 2 CD-ROM, VDE Verlag.
  • Prof. Dr. Birgit Vogel-Heuser (2008) Automation & Embedded Systems, Oldenbourg Industrieverlag.
  • Heinrich Lepers (2005) SPS-Programmierung nach IEC 61131-3 mit Beispielen für CoDeSys und STEP 7, Franzis Verlag
  • Günter Wellenreuther/Dieter Zastrow (2007) Automatisieren mit SPS - Übersichten und Übungsaufgaben, Vieweg Verlag.
  • Norbert Becker (2006) Automatisierungstechnik, Vogel Buchverlag.
  • Igor Petrov: Controller Programming: The standard languages and most important development tools. Solon Press, 2007 (Russian)
  • Marcos de Oliveira Fonseca et al.(2008) Aplicando a norma IEC 61131 na automação de processos, ISA América do Sul. (Portuguese)
  • Dag Håkon Hanssen (2008) Programmerbare Logiske Styringer – baser på IEC 61131-3, tapir akademisk forlag. (Norwegian)
  • Tom Mejer Antonsen (2018) PLC Styring med with Structured Text (ST) - IEC 611131-3 og best practice ST programmering , Book On Demand (Danish)
  • Tom Mejer Antonsen (2018) PLC Controls with Structured Text (ST) - IEC 611131-3 and best practice ST programming , Book On Demand

External links[edit]