During the development of an ECC, it may be
in an intermediate state which, if compiled, could produce behaviors
that would be contrary to the design intent and may even lead to
failure of the control system with accompanying damage or unsafe
operation of the controlled machine or process. The FBDK provides
several validation tools to help you avoid the compilation of
such invalid ECCs:
State dialog automatically prevents the accidental creation of a transient EC state from an existing
unconnected EC state by giving it the name of an event input
that is already in use in an EC transition condition.
The popup menu of the ECC editor
provides a Validate item, which can detect the following
invalid topologies as shown in Figures 1 and 2 below:
Unreachable EC states ("orphan states"), i.e.,
states that are not transient EC
states, and to which a path cannot be found from the EC
initial state by following the directed links defined by the EC
Terminal EC states ("dead end states"), i.e., states
that are reachable, but which do not have any outgoing EC
Unused event inputs, i.e., event inputs of the FB
type containing the ECC that are not used in any EC transitions.
Unused event outputs, i.e., event outputs of the FB
type containing the ECC that are not used in any EC actions.