MULTIPLEXER

PURPOSE:To expand number of communication channels and to acquire a data efficiently by allowing a conversion means to make matching with a communication protocol and a data transmission form of a host computer and allowing a data storage means to revise and register a data of each device. CONSTITUTION:An automatic monitoring circuit 2g of a multiplexer 2 is in operation at application of power and sends a read command to controllers 3-1-3-4. The read command is a command to request the transfer of a sensor data to the controller. When the command is sent to the controllers 3-1-3-4, a frame form communication protocol conversion circuit 2f makes matching with the communication to each controller. On the other hand, each of the controllers 3-1-3-4 transfers the sensor data acquired in response to the read command to the multiplexer 2. Since the operation above is implemented for each prescribed period, the sensor data stored in an internal memory of the circuit 2g is always revised.