摘要
单片机加上接口电路，做成最简PLC，为了方便应用，电路中设置了4组4位拨码开关，可作为时间或者计数值的预置和调整，并通过实例详细介绍了其编程和运用。
By taking the single-chip computer as the main controller, and adding interface circuit, a small PLC is produced to preset and adjust the time or count value, which setting the four series circuit four dial the code switch in circuit, its programming and use were described in detail through an example
