用循环中断ob中计数实现定时器功能,比如ob35中,中断周期是1s

timecounter:=timecounter+1;//计时器计时

if timecounter>=timecounter_sp1 then//计时器超过设定值1(30分钟,即1800)后归零重新计时

   timecounter:=0;

end_if;

if timecounter

"气动阀":=1;

else

"气动阀":=0;

end_if;

if timecounter>=timecounter_sp1 and timecounter_sav<=timecounter_sp1 then//计时器第一次大于设定值,则电机选择切换一次

    motor_select:=1-motor_select;

end_if;

timecounter_sav:=timecounter;//保存计时值

if timecounter>=timecounter_sp1 then//计时大于10分钟则

  if motor_select then//如果motor_select为1,启动电机1,否则启动电机2

     motor1:=1;

  else

    motor2:=1;

  end_if;

else//如果计时小于设定值(10分钟)则电机1和2都关闭

   motor1:=0;

   motor2:=0;

end if;