COMMUNICATION SYSTEM USING SERIAL INTERFACE

摘要

PROBLEM TO BE SOLVED: To provide a communication system using the serial interface of high availability, which can execute communication in the forms of synchronous communication and asynchronous communication without the need of an operation for setting synchronous communication and asynchronous communication with a dip switch. SOLUTION: PCIF (serial interface) 11 is switch-controlled so that a transfer clock for synchronous communication and a status signal for hard flow control are automatically switched and outputted to a status signal line. A block frequency-dividing circuit 23 having plural clock frequencies so that the arbitrary frequency among the plural frequencies of the transfer clock for synchronous communication can be selected is provided. CPU 2 decodes a request command from a personal computer 13 and transmits a selection 2 signal to the frequency- dividing circuit 23 so as to select the clock frequency.