The **PLC-RSP-12DC/21** is a specific type of **PLC-Interface Relay Module** manufactured by Phoenix Contact. It is designed to bridge the gap between low-power control signals (from a PLC) and high-power field devices. Below is a breakdown of its electronic components and specifications. --- ### 1. Component Overview The device consists of two primary parts that work together as a single unit: | Component | Description | | :--- | :--- | | **Relay Base** | The terminal block housing that provides DIN rail mounting and wiring connections. | | **Plug-in Relay** | The electromechanical switching element that can be replaced without disconnecting wires. | | **LED Indicator** | A status light (usually yellow) that illuminates when the coil is energized. | | **Protection Circuit** | Integrated diode for polarity protection and surge suppression. | --- ### 2. Technical Specifications The electronic performance of the module is divided into the **Input (Coil) Side** and the **Output (Contact) Side**. #### A. Input Side (Control) This is the side connected to your PLC or controller. * **Nominal Input Voltage:** 12V DC. * **Typical Input Current:** Approximately 15.3 mA. * **Protective Circuitry:** Includes a **Free-wheeling diode** (to protect the PLC from inductive voltage spikes when the relay turns off) and Polarity protection. #### B. Output Side (Switching) This is the "dry contact" that manages the load. * **Contact Type:** 1 PDT (Power Double Throw) / SPDT (Single Pole Double Throw). * **Contact Material:** Silver Tin Oxide (AgSnO). * **Maximum Switching Voltage:** 250V AC/DC. * **Limiting Continuous Current:** 6A. --- ### 3. Connection Diagram Logic The unit typically uses screw or push-in connections labeled numerically: | Terminal | Function | | :--- | :--- | | **A1 / A2** | Coil connections (12V DC input). | | **11** | Common (COM) contact. | | **12** | Normally Closed (NC) contact. | | **14** | Normally Open (NO) contact. | --- ### 4. Key Advantages * **Isolation:** Provides electrical galvanic isolation between the sensitive 12V DC control logic and high-voltage 230V AC loads. * **Modular Design:** The "RSP" series often features spring-cage or push-in technology for vibration-resistant connections. * **Space Saving:** Slim profile (typically 6.2mm wide) allows for high-density mounting on DIN rails.