| 摘要 |
PURPOSE:To surely transmit data from plural measuring instruments to a data collector without interference by transmitting measured data of a station from its own station only in the state where the absence of a radio wave continues for an independently set transmission delay time after the elapse of a prescribed transmission period. CONSTITUTION:Times td(1) to td(4) are set to measuring instruments 2 #1 to #4 by a transmission delay time timer 261, and this timer 216 outputs the output when a time td elapses after disappearance of the carrier sense output. A transmission interval timer 262 outputs the output when a time ti elapses after the preceding transmission, and AND between outputs of timers 262 and 261 is operated by an AND circuit 263. The transmission delay time td is set to satisfy td(1)<td(2)<td(3)<td(4) with respect to measuring instruments #1 to #4. Thus, measuring instruments do not cause interference by simultaneous transmission and transmit data in the order of #1, #2, #3, and #4 in a regularly manner. |
