### E3JM-R4S4 Photoelectric Sensor: Electronic Overview The **E3JM-R4S4** is a high-performance, rectangular photoelectric sensor manufactured by Omron. It is a **retro-reflective** model that includes a built-in timer and universal voltage power supply capabilities. --- ### Technical Specifications | Feature | Specification | | :--- | :--- | | **Sensing Method** | Retro-reflective (requires a reflector) | | **Sensing Distance** | 4 meters (when using E39-R1 reflector) | | **Power Supply Voltage** | 12 to 240 VDC or 24 to 240 VAC (50/60 Hz) | | **Output Type** | Relay Output (SPDT) | | **Contact Capacity** | 3A at 250 VAC (Resistive load) | | **Response Time** | 30 ms maximum | | **Light Source** | Infrared LED | | **Connection Method** | Terminal Block (Conduit size: G1/2) | --- ### Core Electronic Components & Functions #### 1. Universal Power Supply One of the key electronic features of the E3JM series is its **integrated switching power supply**. It can accept a wide range of voltages (both AC and DC), making it highly versatile for different industrial grids without needing an external transformer. #### 2. E3JM-R4**S4** (Timer Function) The "S4" suffix indicates the inclusion of a **Timer Circuit**. The sensor has a built-in DIP switch and potentiometer that allow for four timing modes: * **ON-delay:** Delays the output activation after an object is detected. * **OFF-delay:** Keeps the output active for a set period after the object leaves. * **One-shot:** Triggers the output for a fixed duration regardless of how long the object stays. * **Normal:** Standard operation without timing logic. #### 3. Relay Output Mechanism Unlike NPN/PNP transistor outputs, the E3JM-R4S4 uses a **mechanical relay (SPDT)**. * **Advantage:** It can switch high-current loads directly (up to 3A). * **Limitation:** It has a slower response time (30ms) compared to solid-state sensors and a finite mechanical lifespan. --- ### Wiring Diagram (Terminal Block) The internal electronics are accessed via a terminal block inside the housing: | Terminal No. | Function | Description | | :--- | :--- | :--- | | **1 & 2** | Power Supply | 12-240 VDC or 24-240 VAC (Non-polar) | | **3** | Common (COM) | Relay Common Contact | | **4** | Normally Closed (NC) | Output is closed when no object is detected | | **5** | Normally Open (NO) | Output is closed when an object is detected | --- ### Indicator LEDs * **Light Indicator (Red):** Lights up when the receiver is receiving light from the reflector. * **Stability Indicator (Green):** Lights up when the light reception is stable (not at the threshold of switching), ensuring reliable operation against dust or misalignment.