PURPOSE: To firmly control the control terminal devices even when signals are simultaneously transmitted or when signals are crossovered, by transmitting the scanning requirement signal frequency modulated with the frequency different from the signal sent from the master station to master station while transmitting the data.
CONSTITUTION: When cotnrol signal and scanning signal are frequency modulated and sent from master station 2 and monitor data are transmitted from condition monitoring terminal device 5, transmit the scanning requirement signal frequency modulated with the frequency different from the signal sent from master station 2 and scan the condition monitoring terminal device 5 after receiving the scanning requirement signal at the master station 2. Monitoring data are detected according to this scanning. Consequently, when the signals are simultaneously transmitted from master station 2 and terminal device 5 or different terminal device 5, these can firmly be discriminated.
YAMAZAKI KIYOUJI
KOBAYASHI HISAO
