IEC 61131-3, CoDeSys standardize control logic programming
Ease control programming across multiple controller platforms using IEC 61131-3 CoDeSys programming software. IEC 61131-3 standard programming drives efficiencies through reduced development and training costs, enabled flexibility, and allowing end users to select the device most suited to their needs, regardless of supplier.
Richard C. Harwell, Kerry L. Sparks, of Eaton Corp.
Control logic programming standardization promotes interoperability and saves engineers time when working with products from multiple vendors. IEC 61131-3 standard programming drives efficiencies through reduced development and training costs, enabled flexibility, and allowing end users to select the device most suited to their needs, regardless of supplier. Designed around that standard, CoDeSys (Controller Development System) software technology opens new roads for the automation industry—including creating controller applications without hardware and programming on a common platform.
In December 1993, the development of IEC 61131-3 was a groundbreaking effort to bring standardization to logic programming. It provided a core programming model with several inherent benefits, including:
- Structured software based on Program Organization Units (POUs)
- Strong and consistent data typing
- Task based execution control.
Beyond the standardization of program structure, IEC 61131-3 defined a standard set of programming languages: ladder logic, function block, structured text, instruction list, and sequential function chart.
By providing a common programming model and language set, the standard has allowed control engineers to work effectively with controllers from different suppliers. This has allowed them to easily understand programs generated for various logic controllers. Additionally, the task of porting a program from one supplier’s programming software to that of another was reduced.
Even though there are many benefits to an IEC 61131-3 program model and languages, control engineers have found themselves “locked in” to one supplier’s equipment. The IEC languages were a step in the right direction; while the program model and base languages may be the same, there are still some large differences:
- Supplier-specific language extensions can prevent interchangeability among control hardware manufacturers
- Look and feel of the programming environment can make it difficult to program on one controller versus another
- Program file storage formats can create compatibility issues with different memory organization, even with the same manufacturer.
Changing among suppliers of IEC 61131-3 controllers can require staff retraining and manual program re-entry. CoDeSys software technology provides an easier-to-use, flexible platform for use of the IEC 61131-3 programming standard.
CoDeSys, a comprehensive open software tool for industrial automation, consists of two parts:
- The programming system CoDeSys, a Common IEC 61131-3 programming tool
- The runtime system CoDeSys Control, which turns any intelligent automation device into an IEC 61131-3 controller programmable with CoDeSys.
The system is designed to easily adapt from one vendor “target” device to another. This means that a control engineer can incorporate multiple targets into one programming environment or move from the programming environment of one CoDeSys controller to another, without retraining. Additionally, program file formats are common and programs can be imported without manual intervention.
Commonality of the CoDeSys Control runtime environment across targets means that a program operates similarly on the new target. Ability to reuse proven control code provides a high level of quality assurance in the critical runtime environment. CoDeSys Control runtime system can deploy on many devices capable of control, like PLCs, operator interfaces, and drives. It is ideally suited to support the trend towards control distributed to end devices (such as operator interfaces and drives), while still allowing best-of-class selection of those devices.
CoDeSys is helping to propel the IEC 61131-3 standard into the future and is increasing adoption by making it simpler to use devices from multiple vendors. It enables end users to select the devices best suited to their needs, by reducing the costs and time associated with migrating from devices manufactured by different vendors.
Richard C. Harwell is advanced solutions manager, and Kerry L. Sparks is senior field marketing specialist at Eaton Corp.
With registration, free CoDeSys versions are available.