Supervisory parallel switching device for computer integrated manufacturing system with secs-compliant serial communication links

Abstract

A supervisory parallel switching device is designed for use with a CIM system including a host computer unit connected via an extended computer integrated unit to at least one equipment unit through an SECS-compliant (Semiconductor Equipment Communication Standard) serial communication link, for the purpose of allowing the equipment unit to be continuously under computer control even in the event of an unanticipated shutdown to the extended computer integrated unit. The supervisory parallel switching device includes a plurality of switching units, such as relays, under control by a control logic unit to be switched on in such a manner that, when the extended computer integrated unit operates normally, the control logic unit activates these switching units to connect both the equipment unit and the host computer unit to the extended computer integrated unit, allowing the equipment unit to be chiefly controlled by the extended computer integrated unit; while in the event of an unanticipated shutdown to the extended computer integrated unit, the control logic unit activates these switching units to connect the equipment unit directly to the host computer unit, thus allowing the equipment unit to be continuously controlled by the host computer unit. This feature allows each equipment unit in the CIM system to be uninterrupted in its fabrication process even where there is power failure or system crash in the extended computer integrated unit.