The **E32-R21 2M** and **E39-R3** are components of an industrial photoelectric sensing system manufactured by **Omron**. They work together using a **Retro-reflective** sensing method. --- ## 1. Component Breakdown ### E32-R21 2M (Fiber Optic Sensor Head) This is the "eye" of the system. It consists of flexible plastic fibers that transmit light from an amplifier to the sensing point and back again. | Feature | Specification | | :--- | :--- | | **Sensing Method** | Retro-reflective | | **Fiber Type** | Plastic, Multicore | | **Fiber Diameter** | 2.2 mm (Outer), 1.0 mm (Core) | | **Cable Length** | 2 Meters (Standard) | | **Bending Radius** | R10 (Standard flexibility) | | **Material** | Stainless steel head, PE (Polyethylene) sheath | ### E39-R3 (Retro-reflector) This is a specialized mirror designed to reflect the light beam sent by the E32-R21 back to the receiver within the same fiber head. | Feature | Specification | | :--- | :--- | | **Type** | Small, standard reflector | | **Mounting** | Self-adhesive or screw-on | | **Compatibility** | Optimized for E32 series retro-reflective fibers | --- ## 2. Principle of Operation 1. **Light Emission:** An external fiber amplifier (like the Omron E3X series) sends light through one half of the E32-R21 fiber. 2. **Reflection:** The light travels out of the fiber head, hits the **E39-R3 reflector**, and bounces back. 3. **Detection:** The reflected light enters the second half of the fiber head and returns to the amplifier. 4. **Trigger:** When an object passes between the fiber head and the reflector, the beam is broken. The amplifier detects the loss of light and triggers an electrical output (PLC signal, relay, etc.). --- ## 3. Installation & Wiring Logic While the fiber itself is passive (no electricity), it must be plugged into a **Fiber Amplifier Unit**. ### Setup Diagram Concept ```text [ Amplifier Unit ] <--- 2m Fiber (E32-R21) ---> [ Fiber Head ] ~~~ Beam ~~~ [ Reflector (E39-R3) ] | ^ |--- Output to PLC | |--- Power (12-24VDC) Object passes here ``` ### Key Advantages * **Space Saving:** The fiber head is much smaller than traditional photoelectric sensors. * **No Electronics at Sensing Point:** Since only light travels through the fiber, it is immune to Electrical Noise (EMI) and can be used in tight or hazardous spaces. * **Easy Alignment:** Because the emitter and receiver are in the same head, you only need to align one device with a reflector. ---