实现功能简介：
1）联动功能：
两部电梯之间相互联动，即同时按下任何一部电梯的外部向上或向下键之后，两部电梯同时接受此指令，然后由系统判断，与该请求所在楼层最近并且运行方向相同的电梯执行指令，另一部电梯不执行该指令。
2）手动开门功能：考虑到在实际生活中可能出现电梯上客时间不够的情况，在电梯内部设置了该功能，按下开门键，电梯延长开门时间。
3）报警功能：本例中为报警状态设置了单独的状态，意在考虑到现实生活中多种多样的报警原因，报警之后，门打开，处于等待修理的状态，在修理完毕之后，按下复位键使得电梯重新开始运行。
Function introduction:
1) linkage function:
Two elevators linkage between, that is, at the same time in an elevator any external up or down key later, two elevators and accept the instructions, then the system judgment, and the request in the floor and running the same direction recently the elevator the instruction execution, another lift not execute the instructions.
2) manual open the door function: to consider in the practical life may appear on the elevator of guest time enough, in the elevator set up inside the function, press the key to open the door, elevator extend time to open the door.
3) alarm function: in the case of the state for alarm set separate state to consider to real life DuoZhong variety of alarm reason, after the alarm, the door opened, in a waiting state of repair, in after the repair, press the reset button to make elevator start running. (2011-11-07, VHDL, 14KB, 下载9次)