The transient EC state (an EC state that has the same name as an event input and is not used as the source or destination of any EC transition) has been proposed as a possible extension to a future edition of the IEC 61499 Standard. The purpose of this extension is to provide a way to achieve immediate execution of one or more EC actions in a defined sequence upon the occurrence of an event at a specified event input, without otherwise affecting the state of the ECC.
The FBDK now includes the following features to support this extension.
EC_TRANSITIONS...END_TRANSITIONSblock if the ECC does not contain any transitions.
To accommodate this extension, the online LibraryElement.dtd Document Type Definition (DTD) has been modified to accommodate ECCs comprising zero or more EC Transitions. Basic FB Types developed with earlier versions of the FBDK are forward-compatible with this DTD.