限位开关是机电或固态设备需要身体接触开关的执行机构，使接触状态改变的对象。主要有两种类型的产品：旋转和直线。旋转限位开关使用物理驱动的杠杆旋转轴和操作开关接触，使他们改变状态。线性限位开关，机电设备，需要一个目标对象和开关激活之间的身体接触，使接触状态改变。专业限位开关也可提供。

不同类型的开关和接触式限位开关。开关类型有两种选择：机电式和固态式。机电限位开关，机械触点，继电器，或芦苇。固态限位开关是电子的，没有运动部件。有接触式三种选择：瞬时接触，保持联系，并积极开放。瞬时接触开关打开或关闭仅在驱动。意味着限位开关触点触发的位置，甚至执行器已被释放后仍然保持着联系。的接触，只有通过进一步的操作头的机械动作复位。积极开放意味着接触点打开可靠，则仍然开放，在激活的位置，甚至在机械故障的情况下，。

正常状态和交换机的配置选择限位开关时要考虑的重要参数。正常状态下有两种选择：常开（NO）和常闭（NC）。常开（NO），开关触点，在开启位置时，中断电路。当启动时，触点闭合。常闭（NC），开关触点，常闭位置时，建立一个电路。当启动时，触点打开。有交换机配置的四种选择：单刀单掷（SPST），单刀双掷（SPDT）;双刀单掷（DPST）;和双刀，双掷（DPDT）。

限位开关不同的定位和性能方面。确定上浆要求时，限位开关调节器的方向是至关重要的。一些限位开关有一个顶部安装的执行机构。其他有侧的限位开关的执行机构。在性能方面，限位开关进行规格最大额定电流，最大额定交流电压，直流电压等级最高，最小机械寿命，电气寿命最低，工作温度。一些限位开关晶体管 - 晶体管逻辑电路（TTL）的使用而设计。

Limit switches are electromechanical or solid state devices that require the physical contact of an object with the switch’s actuator to make the contacts change state. There are two main types of products: rotary and linear. Rotary limit switches use physically-actuated levers to rotate a shaft and operate the contacts in a switch, making them change state. Linear limit switches are electromechanical devices that require physical contact between a target object and switch activator to make the contacts change state. Specialty limit switches are also available.

Limit switches differ in terms of switch type and contact type. There are two choices for switch type: electromechancial and solid-state. Electromechanical limit switches have mechanical contacts, relays, or reeds. Solid-state limit switches are electronic and do not have moving parts.  There are three choices for contact type: momentary contact, maintained contact, and positive opening. Momentary contact means that the switch is open or closed only during actuation. Maintained contact means that the limit switch contacts remain in the triggered position even after the actuator has been released. The contacts are reset only by further mechanical action of the operating head. Positive opening means that the contact-point opens reliably and then remains open, in the activated position, even in the event of a mechanical failure. 

Normal state and switch configuration are important parameters to consider when selecting limit switches. There are two choices for normal state: normally open (NO) and normally closed (NC).   Normally open (NO) means that the switch contacts, when in their open position, interrupt the circuit. When actuated, the contacts close.   Normally closed (NC) means that the switch contacts, when in their normally closed position, establish a circuit. When actuated, the contacts open. There are four choices for switch configuration: single pole, single throw (SPST); single pole, double throw (SPDT); double pole, single throw (DPST); and double pole, double throw (DPDT).

Limit switches differ in terms of orientation and performance. The orientation of the limit switch actuator is critical when determining sizing requirements. Some limit switches have a top-mounted actuator. Others have the actuator on the side of the limit switch. In terms of performance, limit switches carry specifications for maximum current rating, maximum AC voltage rating, maximum DC voltage rating, minimum mechanical life, minimum electrical life, and operating temperature. Some limit switches are designed for use in transistor-transistor logic (TTL) circuit.