工作开关从RUN打到TERM，程序并未STOP，但可以测到工作开关状态，让出通讯口，恢复PPI通讯。
这是HELP中的一段：
Mode_Switch SM0.7 This bit indicates the current position of the Mode switch (OFF=TERM position and ON=RUN position). You can use this bit to enable Freeport mode only when the switch is in the RUN position. Normal communication with the PC/programming device can be re-enabled by switching to the TERM position.