Asynchronous coupling of data between a word-oriented I/O module and the memory of a programmable controller

摘要

A programmable controller includes a controller processor which operates in response to a control program to transfer command words stored in a data table to an input/output image table in the controller memory. An input/output scanner circuit operates asynchronously with respect to the controller processor to couple command words in the output image table to one or more of a plurality of word-oriented I/O modules and to couple command words from an I/O module to the input image table. A pulse module is described for receiving such command words and controlling the operation of a stepping motor and an analog output module is described which converts a digital number in such command words to an analog output signal.