Abstract: A system and method for synchronizing a plurality of main processors. At a first time and in response to a first time reference, a first rendezvous signal is sent from a first to a second of the plurality of main processors. At a second time, and in response to a second time reference, a second rendezvous signal is sent from the second of the plurality of main processors, to the first of said plurality of main processors. After the first rendezvous signal is received by the second of the plurality of main processors and the second rendezvous signal is received by the first of said plurality of main processors, substantially simultaneous scanning of control information is initiated by the first and second of the plurality of main processors. In variations, a difference between the first and second times signals a fault condition.

Abstract: A computer system for generating a cause effect matrix as a user interface to develop a control program based on the cause effect matrix and to compile and download the resulting program into a programmable controller. A cause effect matrix diagram is used to develop a function block diagram program which is a standard IEC 1131-3 language. The function block diagram is translated into structured text which is compiled into intermediate code. The intermediate code is translated into the native code for the micro-processor of the target control system, including but not necessarily limited to the Motorola processor MPC-860. The automation of a cause effect matrix diagram to generate a function block diagram permits additional capability by allowing functions for causes, intersections, and effects. Because special functions may be included, the results of a cause generate timing functions or other computations before initiating the effect.