The **FP2-S120-R** is a specific module within the Panasonic (formerly Matsushita/NAiS) **FP2 series** Programmable Logic Controller (PLC) system. Specifically, it is a **Remote I/O Slave Station** module. Below is the detailed breakdown of its electronic parts, specifications, and function. --- ## 1. Core Functionality The FP2-S120-R acts as a communication bridge. In a large automated system, it allows you to place I/O modules far away from the main CPU, connecting them back to the master via a single twisted-pair cable (Remote I/O Link). ### Electronic Specifications | Feature | Specification | | :--- | :--- | | **Product Category** | Remote I/O Slave Unit | | **Compatible Series** | Panasonic FP2 / FP2SH | | **Communication Method** | MEWNET-F (Proprietary Fieldbus) | | **Transmission Speed** | 500 kbps | | **Max. Distance** | Up to 700 meters | | **Mounting Position** | Fits into the CPU slot of an expansion backplane | --- ## 2. Key Physical & Electronic Components The unit consists of several critical interfaces and internal circuit blocks: ### A. Communication Interface * **Terminal Block:** Located on the front, used for connecting the twisted-pair cable (Data+, Data-, and Shield). * **Pulse Transformer:** Internally provides galvanic isolation for the communication signals to protect the backplane from surges. ### B. Configuration Switches (DIP Switches) * **Station Number Setting:** Rotary or DIP switches are used to set the unique address of the slave unit so the Master CPU can identify it. * **Baud Rate/Mode Selectors:** Internal switches to match the communication parameters of the Master unit. ### C. Status Indicators (LEDs) * **PWR (Power):** Indicates the unit is receiving 5V DC from the backplane. * **RUN:** Indicates the unit is actively communicating. * **ERR (Error):** Flashes or stays lit if there is a parity error or communication timeout. * **SD/RD:** Send Data and Receive Data indicators for monitoring traffic. ### D. Internal Logic * **Bus Interface ASIC:** A proprietary chip that translates the MEWNET-F protocol into the parallel bus protocol used by the FP2 backplane. * **Voltage Regulator:** Converts the backplane power to the specific voltages required by the internal ICs. --- ## 3. System Architecture Role The FP2-S120-R essentially "fools" the expansion rack into thinking it is connected directly to the CPU. 1. **Input:** Signals from local I/O modules on the slave rack are digitized. 2. **Packetizing:** The FP2-S120-R bundles these signals into a data packet. 3. **Transmission:** The packet is sent over the MEWNET-F link to the **FP2-RMV** (Master Unit). 4. **Output:** Commands from the Master CPU are received and distributed to the output modules on the slave rack. --- ## 4. Connection Diagram (Electrical Layout) ```text [ Master CPU Rack ] <---- Twisted Pair ----> [ FP2-S120-R ] | [ Backplane Bus ] / | \ [Input] [Output] [Analog] ```