Metal treating process control

Input and output capacity of a continuous cycling programmable controller is increased by utilizing a program which defines a series of timing windows or channels each of which extends for a period greater than a single program cycle. Control switches and sensing switch devices and output LEDS, are divided into channel groups which are energized only during the corresponding channel timing window. Readings of energized input devices are taken during input timing windows which are delayed from and shorter than the corresponding energized window to account for output and input delay and startup and stopping irregularities. Additionally, light indicators are incorporated within a graphic display having an arrangement of baths depicted spatially relative to a corresponding arrangement of control units to enable substantially easier identification of the various control conditions of the process.