PURPOSE: To improve the data transfer efficiency by switching the setting of a communication channel corresponding to a data transfer flow state in the set communication channel so as to prevent deterioration in the data transfer efficiency due to non-transfer state of data.
CONSTITUTION: Channel flow state monitor sections 18-21 monitor a flow state of channel data set by the connection of crossbar switch contacts 12-15 (measurement of length of time and its frequency when a WAIT-S and R-signal is active). When the measured time interval is extended to be a prescribed value or over, it is discriminated that the state of transmission restriction or under-run takes place on a channel and the data non-transfer state is informed on the channel to a control section 11 via a control line 22. The control section 11 receiving the data non-transfer state detection result from the monitor sections 18-21 changes the connection of a switch used to set the channel into the connection based on the data transfer request sent from other device to any of two devices connected by the channel.
NISHIMURA KAZUTOSHI
MARUYAMA MITSURU
