SYSGO: Distributed Application in IEC 61499As a partial result of the BaSys 4.0 project (, the runtime environment FORTE now officially supports running on the PikeOS virtualizing Real-Time Operating System.
FORTE, which itself is a part of the Eclipse 4diac™ ( framework, is one of the most comprehensive and mature implementations of an IEC 61499-conforming system. This norm itself is a successor of the venerable IEC 61131, which has been the industry standard for all programmable logic controllers (PLCs) since 1992.
IEC 61499—and thus, FORTE—takes the established concepts of function blocks a step further, adds asynchronous events and introduces the notion of applications that can be distributed over multiple PLCs. A two-step process provides maximal flexibility: The function blocks are first placed and connected in a graphical editor. The blocks can be arbitrarily complex, from a simple “ADD” function to a complete PID controller and beyond. Once they are ready to be deployed, the integrator assigns each block to an existing hardware resource. Using a publish/subscribe mechanism, the IEC 61499 run time environment ensures that all events are delivered to their correct recipients.

Operating FORTE on top of PikeOS instead of Linux yields a number of benefits. With its certifiable Safety Assurance capability according to IEC 61508 up to SIL4, it’s in any case a good fit for critical industrial processes. When adding a new functionality to a 61499 PLC, the virtualization capability of PikeOS allows the system architect to encapsulate it in its own partition. These partitions act as virtual machines, running independently with strong isolation against each other and the OS. In an Industry 4.0 scenario, PLCs will be forced to support many new features: reloading function block types during runtime, self-configuration of components by fetching necessary information from the Asset Administration Shell (AAS), or service discovery within a network, just to name a few.

With the combination of 4diac FORTE with the PikeOS platform, system architects obtain the tools to design IEC 61499-compatible solutions that compromise neither on safety nor on security.

Authors: Caspar Gries (SYSGO AG), Dr. Monika Wenger (fortiss GmbH)