as described in (2012) The IEC 61499 Function Block Standard: Software Tools and Runtime Platforms:
The 4DIAC-RTE (FORTE) is a small portable implementation of an IEC 61499 runtime environment targeting small embedded control devices (16/32 Bit). It provides the execution of basic function blocks, composite function blocks, and service interface function blocks.
The execution mechanisms in FORTE allow the realtime constrained execution of IEC 61499 control configurations triggered by external events, where different parts of the configuration can fulfill different realtime constraints and the execution of low priority processes does not disturb the execution of higher priority processes .
FORTE has been written to be platformindependent, to make it easy to target to diverse hardware and operating system platforms. Currently the open source version has been ported to four operating systems: POSIX (mainly Linux), Microsoft Windows (Win32), ThreadX, and eCos, the last two being realtime operating systems for embedded control systems. These ports have been tested on different hardware platforms ranging from a normal PC to small embedded control devices (e.g., for motion control).
Currently the smallest platform supported by the open source version is the Lego Mindstorms NXT controller. Like the 4DIAC-IDE software tool, FORTE is a product of the 4DIAC open source project, and updated versions of both FORTE and 4DIAC-IDE are provided simultaneously in the same release cycle.
Under its Eclipse Public License , changes to the FORTE open source code have to be provided under the EPL, but vendorspecific additions do not have to be made open source. Thus, this code can serve as the basis for multiple commerciallysupported versions; for instance, the commercial runtime environment nxtRT61499F described below is based on FORTE.
Configurability of the FORTE platform by the FBDK and nxtSTUDIO tools, as well as by the 4DIAC-IDE tool, and its interoperability with the FBRT and nxtRT61499F runtime platforms, have been informally tested.