‘Extras’ ‘Order’ ‘Order everything according to data flow’

This command effects all elements. The order of execution is determined by the data flow of the elements and not by their position. The diagram below shows elements which have been ordered topographically.

Sequence before the ordering according to data flow:

The following arrangement exists after selecting the command.

Sequence after the ordering according to data flow:

When this command is selected the first thing to happen is that the elements are ordered topographically. A new sequential processing list is then created. Based on the known values of the inputs, the computer calculates which of the as yet not numbered elements can be processed next. In the above “network” the block AND, for example, could be processed immediately since the values at its inputs (1 and 2) are known. Block SUB can only then be processed since the result from ADD must be known first, etc.

Feedback paths in CFC are inserted last.

The advantage of the data flow sequencing is that an output box which is connected to the output of a block comes immediately after it in the data flow sequencing system which by topological ordering would not always be the case. The topological ordering can deliver another result in some cases than ordering by data flow, a point which one can recognise from the above example.