Order of Evaluation of Networks

The order in which networks and their elements are evaluated is not necessarily the same as the order in which they are labelled or displayed.When the body of a program organization unit (POU) consists of one or more networks, the results of network evaluation within said body are functionally equivalent to the observance of the following rules:

• No element of a network is evaluated until the states of all of its inputs have been evaluated.
• The evaluation of a network element is not complete until the states of all of its outputs have been evaluated.
• As stated when describing the FBD editor, a network number is automatically assigned to every network. Within a POU, networks are evaluated according to the sequence of their number: network N is evaluated before network N+1, unless otherwise specified by means of the execution control elements.