用簡單設(shè)計法設(shè)計一個對鍋爐鼓風機和引風機控制的梯形圖程序??刂埔螅?br /> (1)開機前首先啟動引風機,10S后自動啟動鼓風機; (2)停止時,立即關(guān)斷鼓風機,經(jīng)20S后自動關(guān)斷引風機。