Start up and press the limit switch all the time

Cause analysis:
① Check whether the limit switch is good or not.
② Check whether the wiring from the limit to the mainboard is normal.
Solution:
① Check the measuring limit line.
② Judge whether the limit switch is good or not
(The machine is connected to the normally open contact. When the meter is turned to the buzzer, one probe is connected to the common terminal of the limit switch,
The other probe is connected to NO. At this time, it is not connected. When the iron sheet contact is pressed,