| 摘要 |
PURPOSE:To save the power consumption of an input circuit by making the current flowing through an external contact circuit flow in every n-circuit of the input circuit in a time division and sampling an input data synchronously with the signal. CONSTITUTION:A pulse generated in an oscillator 24 is inputted in 4-bit counter 25, and a decoder driver circuit 26 turns on a semiconductor switching circuit 22a and one of switches 22 to introduce a signal through an external contact 21 into an input receiving photocoupler 23. The signal is sampled in a shift register 27 by a pulse from an oscillator 24. The information of a register 27 is set up in a latch circuit 28 by a carry signal from the counter 25. Namely, the signal of the contact 21 is set up in the circuit 28 in every n (=16) bits. When requiring external contact information, a computer can open a gate circuit 29 and read out the data in the circuit 28. Since the current flowing through the external contact 21 is multiplexed by the circuits 22 and 22a, it is possible to control the current flow within one circuit at maximum, so that power saving design is made available. |
