2 key analyses of reed sensor state detection in automation control

What is a reed switch?

A reed switch is a type of mechanical magnetic switch belonging to the magnetic sensor category. In daily life, reed switches are also commonly used in applications such as door magnetic alarms, bicycle speedometers, and liquid level sensors.When a manufacturer encapsulates the reed switch into an installable industrial sensor — with protective plastic or metal housing, cables, and connectors, allowing it to output electrical signals — it becomes a complete sensor product.Such sensors can be used for limit position detection of pneumatic cylinder pistons, and at this stage, it is referred to as a finished limit reed switch sensor containing a reed switch element.

The Features of Industrial Limit Reed Sensor

The limit reed switch sensor is specifically used for detecting the position and status of cylinder pistons, and it has the following features and advantages:

Non-contact detection:The Magnetic switch sensor is triggered by a magnetic field without direct contact with the detected part, reducing mechanical wear and extending service life.

Compact structure and small size:This sensor consists of a sealed glass tube and a magnetic sensor reed, making it lightweight and easy to install in tight spaces such as cylinders, slides, and valves.

Switch-type output:The sensor reed provides an ON/OFF signal output, responding quickly and operating clearly, which is ideal for limit or position detection.

Sealed packaging:The glass enclosure is filled with inert gas, offering dustproof, oil-resistant, and waterproof performance, making it suitable for harsh industrial environments.

No external power:Since the reed sensor is a mechanical contact structure, it can output a signal directly without any power supply or amplification circuit.

High reliability and long service life:One of the indispensable features of the reed sensor in industrial manufacturing is its stable operation, high repeatability, and mechanical life exceeding millions of cycles, resulting in low maintenance costs.

The specific installation location of the reed switch in the pneumatic actuator

T-slot or dovetail groove:

Front cover or rear cover:

Elongated rectangular groove:

Annular groove:

How does a limit reed switch magnetic work?

Do you know the working principle of reed magnetic switch sensor?Inside the reed switch magnetic sensor, there are two thin, flexible magnetic nickel-iron alloy reeds sealed in a glass tube. The ends of the reeds are slightly separated, remaining open when no magnetic field is present. When an external magnet approaches, the magnetic field magnetizes the reeds, causing them to attract each other, closing the contacts and completing the circuit. Once the magnet moves away, the reeds return to their original position, breaking the circuit again.

Pneumatic actuator with reed sensor applications in Industrial Automation

Automotive manufacturing applications of reed sensor

Pneumatic systems:
Used in pneumatic components such as cylinders and valves to detect piston positions, transmitting digital ON/OFF signals to PLCs or relay circuits for logical control.

Packaging and assembly automation equipment:
Used to determine the end position of slides or robotic arms in packaging machinery, preventing overtravel and ensuring limit detection.

Valve and fluid control systems:
Used to detect the open/closed status of pneumatic and hydraulic valves, preventing operator errors and protecting equipment.

Industrial doors, warehousing, and logistics automation:
The reed sensor can serve as a limit detection switch to determine whether doors, trays, or lifting devices are in position.

Advantages of Reed Sensor

Non-contact detection, long life, and high reliability
Simple structure, small size, easy installation
Tolerant to dust and slight contamination
Low cost, suitable for mass application

Comparison with Other Magnetic Sensors

Reed magnetic sensor VS Hall sensor

Hall sensors can also be used in pneumatic systems, providing more stable detection for fast or high-frequency operations.

Advantages: No mechanical wear, fast response speed, long service life.
Disadvantages: Requires external power supply, more complex circuitry, higher cost than reed type.

Reed magnetic sensor VS Magnetoresistive sensor

Magnetoresistive sensors are the most sensitive, precise, and fastest responding among the three types of magnetic sensors.

Advantages: Higher detection sensitivity and response speed, strong anti-interference, and stable performance.
Disadvantages: Besides higher cost and complex circuitry, they are sensitive to magnetic pole direction and environmental magnetic noise, requiring a well-controlled operating environment.

Choosing the Right Sensor Type

If your system only needs basic limit detection, has budget constraints, lacks a power supply, and offers convenient installation space, the reed sensor is a suitable choice.

If your equipment requires faster response and longer sensor life with stable output, you can choose a Hall sensor.

If your device requires high precision, high sensitivity, and continuous displacement detection, then a magnetoresistive sensor is more suitable.