JPS6449351A - Data communication system - Google Patents

Abstract

PURPOSE:To improve data transferring function and transferring efficiency by providing in a control device a measuring signal sending means to a measuring signal line, a measuring signal detecting means, a measuring means to measure a time from the sending of a measuring signal to the detecting of the signal and a means to set the period of a transmitting signal according to this measured value. CONSTITUTION:When the power source of a control device 20 is turned on, a measuring circuit 2 causes a timer 1 to be enable by a signal line 103 and sends the measuring signal to a signal line 101 simultaneously. The measuring signal passes through a measuring signal line 100 and it is detected from a signal line 102 through a receiver 5 by the measuring circuit 2. The measuring circuit 2 to detect the measuring signal stops the timer 1 by the signal line 103 and instructs the setting of a transferring speed to a transferring clock generating circuit 3 by a signal line 104. The value of the timer 1 at such a time is determined by the lengths of input and output interface cables 201 and 202. The transferring clock generating circuit 3, to which the setting of the transferring speed is instructed, sets the maximum data transferring speed to be transferable by the value of the timer 1 and hereafter, the data transferring can be executed at the set speed.