Patent ID: 7472206

Claim:
A communication control apparatus in a control apparatus having a measurement unit which measures the position of a controlled object, a control processor which computes digital control data for controlling the controlled object according to measured data by the measurement unit, a driving unit which drives the controlled object according to the digital control data, and a host processor which sends command data corresponding to a predetermined command to the control processor; the communication control apparatus comprising: a switching unit, adapted to switch configuration of a communication circuit that is capable of providing at least two communication channels at the same time, depending on the configuration, between the measurement unit and the control processor, the control processor and the driving unit, or the control processor and the host processor; a transfer unit, adapted to transfer the measured data, the digital control data, and the command data through the communication channels provided by the communication circuit by way of Direct Memory Access (DMA) transfer; a setting unit, adapted to set, among data transferred through DMA transfer, a higher priority on data transferred at every predetermined sampling period than on data transferred regardless of the predetermined sampling period; a receiving unit, adapted to receive a DMA transfer request from at least one of the processors; a communication unit, adapted to initiate data communication through DMA transfer in response to the DMA transfer request; a comparing unit, adapted to, when a new DMA transfer request is received during the DMA transfer initiated by the communication unit, compares a priority of the data currently being transferred with a priority of data relating to the newly received DMA transfer request; and a transfer control unit, adapted to interrupts the DMA transfer of the data currently being transferred and initiates DMA transfer of new data relating to the newly received DMA transfer request, if a comparison by the comparing unit shows that the priority of the data relating to the newly received DMA transfer request is higher than the priority of the data currently being transferred, wherein the transfer control unit makes the switching unit switch the configuration of the communication circuit so that the transfer unit is capable of transferring said new data through a communication channel provided by the communication circuit.