if (qs==0) then
     if(a>a1) then
      jump=18
      SetData(jump"Local HMI",rw,200,1)//跳轉窗口
    
     else if (a==a1)then
       if (b>b1 ) then
            jump=18
            SetData(jump"Local HMI",rw,200,1)//跳轉窗口
          
     else if(b==b1) then
         if(c>=c1)then
             jump=18
             SetData(jump"Local HMI",rw,200,1)//跳轉窗口
         end if
       end if
     end if
  end if
      

不懂，感覺你只考慮了a>a1;a=a1,那么a<a1呢？b也一樣。