The **MLS-21-R** is a specific model of a **Magnetic Proximity Sensor** (or Magnetic Reed Switch), typically used in industrial automation, security systems, and pneumatic cylinder position sensing. --- ### 1. Technical Specifications The "R" in the suffix usually denotes a **Reed Switch** type output (mechanical contact), as opposed to solid-state (PNP/NPN). | Feature | Specification (Typical) | | :--- | :--- | | **Sensor Type** | Magnetic Reed Switch | | **Output State** | Normally Open (NO) | | **Operating Voltage** | 5V - 240V AC/DC | | **Switching Current** | 100mA Max | | **Contact Rating** | 10W Max | | **Voltage Drop** | 2.5V Max | | **Indicator** | Red LED (Standard) | --- ### 2. Internal Components The electronic assembly of the MLS-21-R is relatively simple but robust for industrial environments: * **Reed Switch Glass Tube:** The core component containing two ferromagnetic blades. When a magnetic field (from a cylinder piston or external magnet) approaches, the blades pull together to close the circuit. * **Protection Diode/Resistor:** Internal circuitry to protect the LED indicator and ensure the reed contacts do not weld under minor surges. * **LED Indicator:** A small surface-mount LED that illuminates when the magnetic field is detected and the circuit is closed. * **Encapsulation:** The internal parts are usually potted in epoxy resin inside a plastic housing to provide vibration resistance and IP67-rated waterproofing. --- ### 3. Wiring Configuration The MLS-21-R typically uses a **2-wire** configuration. Because it is a mechanical reed switch, it can often handle both AC and DC loads. ```yaml Wiring Diagram: Brown Wire: Connect to Positive (+) or Line (L) Blue Wire: Connect to Load -> then to Negative (-) or Neutral (N) ``` > **Note:** Since it is a 2-wire sensor, there is a small voltage drop across the sensor when "closed" due to the LED indicator. Ensure your PLC or controller can trigger at the remaining voltage. --- ### 4. Application Use Cases 1. **Pneumatic Cylinders:** Mounted in the "T-slot" or "C-slot" of an air cylinder to detect if the piston is extended or retracted. 2. **Door/Gate Sensing:** Used as a non-contact limit switch. 3. **Safety Interlocks:** Ensuring a guard is closed before a machine starts. ---