Capturing data during operation of an industrial controller for the debugging of control programs

Abstract

An industrial controller module () is provided with a routine of program instructions () for storing a log of I/O table state changes () in a defined portion of memory (). Upon the occurrence of a trigger event, a file of the state changes () is saved in the memory (). Each entry () in the log of I/O table state changes () includes a timestamp () and values of each word of I/O state data () that changed at a time of the timestamp. Logs of state change data (), including timestamp data can also be saved for intelligent sensors and actuators () and uploaded with the log of controller processor state data () to a computer () with a diagnostic program () for playing back the state changes and synchronizing changes of the intelligent sensors and actuators () with changes of the controller processor module ().