使用异步定时器编写一个数据采集的多线程程序.doc

实验七任务使用异步定时器编写一个数据采集的多线程程序，和普通定时器比较二者运行时的差异。实验步骤步骤1：设计程序界面，生成程序框架。根据实验要求，我们在面板上放置两个带状图控件，分别用于显示异步定时器和普通定时器的采样结果；放置一双态按钮来控制数据采集的开始和关闭。最终界面如图9-1所示，其主要控件的基本属性列表见表9-1。图9-1 最终用户界面表9-1 主要控件基本属性列表控件类型constant name 属性设置面板panelpanel命令按钮command buttonquitbuttoncallback functionquitcallbacklable_quit双态按钮toggle buttontogglebuttoncallback functiondaqcontrolcbinitial stateofflable数据定时器控件timertimercallback functiondataaquirtimercbinterval (seconds)1.0带状图控件strip chartstripchartlable普通定时器stripchart_2lable异步定时器步骤2：添加异步定时器。把异步定时器的仪器驱动程序添加到当前工程，在工程窗口选择editadd file to projectinstrument(*.fp)，路径为cvitoolslibtoolboxasynctmr.fp。步骤3：获得异步定时器句柄，在main函数添加如下语句：static int asynctimerid;/*先声明句柄变量*/int main (int argc, char *argv)if (initcvirte (0, argv, 0) = 0)return -1;/* out of memory */if (panelhandle = loadpanel (0, lesson9.uir, panel) 0)return -1;displaypanel (panelhandle); /*获得异步定时器句柄*/asynctimerid=newasynctimer (1.0, -1, 0, asynctimercb, 0);runuserinterface ();discardpanel (panelhandle);return 0;步骤4：声明异步定时器回调函数。在main函数之前声明。/*声明asynctimercb*/int cvicallback asynctimercb (int reserved, int timerid, int event, void *callbackdata, int eventdata1, int eventdata2);步骤5：编写回调函数。/*双态按钮回调函数daqcontrolcb*/int cvicallback daqcontrolcb (int panel, int control, int event,void *callbackdata, int eventdata1, int eventdata2)int i;switch (event)case event_commit:getctrlval (panelhandle, panel_togglebutton, &i);setctrlattribute (panelhandle, panel_timer, attr_enabled, i);setasynctimerattribute (asynctimerid, async_attr_enabled, i);break;return 0;/*普通定时器回调函数dataaquirtimercb*/int cvicallback dataaquirtimercb (int panel, int control, int event,void *callbackdata, int eventdata1, int eventdata2)double data;switch (event)case event_timer_tick:data=(double)rand ()/rand_max*100.0;plotstripchartpoint (panelhandle, panel_stripchart_2, data);break;return 0;/*异步定时器回调函数asynctimercb */int cvicallback asynctimercb (int reserved, int timerid, int event, void *callbackdata, int eventdata1, int eventdata2)double data;switch (event)case event_timer_tick:data=(double)rand ()/rand_max*100.0;plotstr