Abstract: The present invention is concerned with a method of deselecting the features of a xerographic printing machine to be able to continue operation of the machine even though a fault has been detected. In particular, the control isolates a detected malfunction to a particular input or output, determines that the particular input or output is related to a specific machine feature that has been selected for a particular job requirement, and instructs the operator by message to deselect that particular feature for continued machine operation. In the event that the isolated fault is related to a machine feature that has not been selected for the particular job requirement or that is not in that particular machine configuration, the control ignores the indicated fault for the continued operation of the machine.

Abstract: The present invention includes a plurality of input/output processors communicating with a master processor. Each of the input/output processors has a filtering mechanism to filter the inputs before transmission to the master over the communication channel precluding the necessity of filtering at the master. More importantly, the shared communications system is not loaded down with every change of an input. Because of this feature, only meaningful changes are put on the communication line, thus substantially reducing its load which makes its effective response time stay high. The inputs when received at the master can be immediately handled to improve the central processor response time. Two types of filtering are provided, in particular, transition and debounce filtering to respond to switch and sensor inputs. Also, there is provided a means to programmably select the type of filter and the time period of filtering.