作一图形，鼠标响应及颜色变化挂变量“tag_1”,再作一I/O挂变量"xitongshijian"，用画面周期触发（画面周期为250MS）
你可观察其变化，代码如下：

if(GetTagBit("tag_1"))
{
SetTagWord("xitongshijian",GetTagWord("xitongshijian")+1);
if(GetTagWord("xitongshijian")==4)
{SetTagWord("xitongshijian",0);
SetTagBit("tag_1",0);}}
else
SetTagWord("xitongshijian",0);
return GetTagWord("xitongshijian");