构建停车信号灯。创建从0到2变化的刻度盘控件，该控件具有3个LED显示：绿色、红色、黄色。当在刻度盘0位置时，使VI打开绿色LED 在1刻度时，打开黄色LED；在2刻度时，打开红色LED。-Construction of parking lights.Create from 0 to 2 changes in the dial control, this control has 3 LED display: green, red, yellow.When the dial 0 position, make VI open the green LED　on 1 scale, open the Yellow LED　on 2 scale, open the red LED.