Programmable sequence control method and devices

Abstract

A programmable sequence control apparatus including a first memory device for storing sequence program instructions, an input/output device, a relay ladder operation device for executing logic operations for a relay ladder circuit having n rows and m columns (wherein n and m are positive integers) in accordance with the program instructions, and a control device for delivering control signals to the relay ladder operation device, is so constructed that the control device includes a memory device for storing contact data and branch data for one column j (wherein j=1, 2, . . . , m) of the relay ladder circuit temporarily, the relay ladder operation device includes first and second registers of a series-in and parallel-out mode which receive and store the contact data and the branch data for the column j, respectively, a third register normally operable in a parallel-in and parallel-out mode, and a gate circuit including logic elements for executing logic operations for the column j based on the parallel delivered outputs of the first and second registers and a third register storing the operation results for the preceding column (j-1), and the relay ladder operation device repeats the aforementioned operation for all of the columns of the relay ladder circuit.