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

A supervisory parallel switching device for use with a CIM system including a host computer unit connected by a SECS-compliant serial communication link via an extended computer integrated unit to at least one equipment unit, for the purpose of connecting the equipment unit directly to the host computer unit in the event of a shutdown to the extended computer integrated unit;

• wherein the host computer unit and the equipment unit each has a communication port of a standardized type, while the extended computer integrated unit has a first passthrough port and a second passthrough port;
• the supervisory parallel switching device comprising:
• (a) a set of connecting ports, including a first connecting port which is connected to the communication port of the host computer unit;
• a second connecting port which is connected to the second passthrough port of the extended computer integrated unit;
• a third connecting port which is connected to the first passthrough port of the extended computer integrated unit;
• and a fourth connecting port which is connected to the communication port of the equipment unit;
• (b) switching means capable of being selectively switched between a first switch position and a second switch position in such a manner that when being switched to the first switch position, the switching means connects the fourth connecting port to the first connecting port;
• and when being switched to the second switch position, the switching means connects the fourth connecting port to the third connecting port and meanwhile connects the first connecting port to the second connecting port;
• and
• (c) a control logic unit, capable of detecting whether the extended computer integrated unit is in a normal operating state or in a shutdown state;
• wherein
• when the extended computer integrated unit is in a normal operating state, the control logic unit activates the switching means to be switched to the second switch position, thereby linking the equipment unit through the extended computer integrated unit to the host computer unit, and
• when the extended computer integrated unit is in a shutdown state, the control logic unit activates the switching means to be switched to the first switch position, thereby linking the equipment unit directly to the host computer unit.