1. A method of programming a highly distributed industrial controller comprised of a plurality of physically distinct modules communicating along a shared communications link, the modules transmitting and receiving messages on the communications link, the method of programming comprising the steps of: (a) generating a logical diagram depicting the industrial controller in the form of an electrical schematic of electrical symbols on an electronic display screen, the electrical symbols representing elemental electrical functions and having at least one input terminal and at least one output terminal, the terminals representing points between which current flows according to the elemental function, each terminal having a state indicating current flow, the terminals connected by lines representing wires to terminals of other electrical symbols and wherein one such electrical symbol is connected to a power source symbol; (b) generating a physical diagram, on the electronic display screen, showing outlines representing the modules surrounding physical symbols representing the elemental functions to be performed by the modules; (c) programming the modules to emulate the elemental function of the physical symbols associated with the module by the physical diagram; and (d) compiling the physical and logical diagrams to generate a communications table establishing communications between the modules on the communications link so that the elemental functions executed by a given module may communicate the state of their terminals with other elemental functions in other modules as if the electrical symbols of those elemental functions were wired together according to the logical diagram.