At present, the limit of the door opener manufacturers on the market is divided into two types of switches.
1. Mechanical spring switch - normally open principle When the door body block touches the spring switch, the metal shrapnel in the switch pulls the output short-circuit signal to the controller, otherwise the normally closed type touches the spring switch, the metal shrapnel opens, and the output is broken. Open signal
2. Reed switch type limit switch is widely used in the market due to its low cost, high durability and high stability. It is also divided into normally open and normally closed type. When the magnet is close, the normally open reed switch is used for suction. The output short-circuit signal, the normally-closed reed switch is output to the controller, and the main controller program issues a command relay to stop outputting power to the motor to achieve the automatic door stop operation limit.
3. Speaking of these, someone should be anxious, why not quickly talk about the damage of the limit switch will affect the normal operation of the door opener, if a closed limit switch is damaged, when the door is in the open limit position, this time, you Press the remote control to close, the door can not be closed, the sliding door motor does not respond, this is the damage to the limit position has been output short circuit signal to the electric door controller, resulting in the door can not be closed, there is another situation is some unprofessional installation The open limit magnet senses the limit limit, so it can't be closed (the magnet fixed height is not correct);
The same problem occurs when the normally closed limit switch has the same problem as the normally open type. However, 99% of the limit switches in the market are normally open. Checking with a multimeter can make the knowledge of what type.