Abstract: A configurable I/O arrangement for a controller has a number of internal and external input/output terminals, each of which are field selected as either an input or an output terminal. Logic functions of the controller are configured for a number of output terminals using up to 32 internal logical states and the states of 32 external physical I/O points. The update timing for each logic circuit is selectable to be synchronized in several different ways: synchronous with an internal event within the controller, synchronous with an event external to the controller, and asynchronous. The I/O arrangement includes a combination of a synchronous latchable input state array, user configurable means for logically combining the output signals of the reading circuits, and means for actuating external devices as a function of the logical combinations of the output signals of the reading circuits.