| 摘要 |
PURPOSE:To add a serial communication function without increasing terminals, by using an earphone jack/for stereo for a double purpose, in an electronic type watthour meter wherein a watthour meter and a var-hour meter are integrated and metering pulses of these two meters are taken out in the earphone jack for testing through photocouplers. CONSTITUTION:At the time of testing, a pulse switching signal 27 is made 'H' and a watthour pulse P1 and a var-hour pulse P2 are taken outside an earphone jack 11 through photocouplers 12 and 13 respectively. At the time of communication, the pulse switching signal 27 is made 'L' and output of the pulses P1 and P2 is checked. Transmission is executed through a route of a serial communication circuit 26 a gate G3 the photocoupler 12 the earphone jack 11, while reception is executed through a route of the earphone jack 11 a photocoupler 24 for reception the serial communication circuit 26. |
