| 摘要 |
PURPOSE:To transfer an emergency report even if a main equipment and a terminal equipment are busy, by causing an instantaneous change in the DC voltage applied to a two-wire line and by controlling a terminal equipment stop function, in the course of the operation of the terminal equipment-side service function. CONSTITUTION:The main equipment is provided with receiver DET2 which has the voltage detection function to detect an instantaneous change of the DC power source voltage applied to the two-wire line and relay control circuit DRV which operates the power source control function so that the DC power source polarity is released in response to the detection output of DET2. In the terminal equipment, when emergency service device TMR2 is operated, an instantaneous change is caused in the DC power source voltage applied to the two-wire line, and oscillator stop switch PB0 is operated to stop temporarily the generation of the answer back signal due to signal oscillating device OSCr. As a result, the emergency report is transferred even if the main equipment and the terminal equipment are busy. |
