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.
- You can Add a transient EC state to the ECC directly from a list of available event input names in the Add State submenu of the ECC's popup menu.
- You can Edit a transient EC state in the EC State Dialog.
- The list of event input names in the EC Transition Dialog is limited to those that are not currently in use as the names of transient EC states.
The text under the src tab does not include an
EC_TRANSITIONS...END_TRANSITIONSblock if the ECC does not contain any transitions.
The Java™ code generated via the File
Save dialog includes special provisions for efficient execution of
transient EC states. You can use the FBDK to compare and contrast the generated code
for the functionally equivalent Basic FB types
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.