**MNET (MECHATROLINK Network)** is an industrial communication protocol and hardware architecture designed by Yaskawa, primarily used for high-speed motion control and factory automation. --- ## 1. Core Electronic Components of MNET The hardware structure of MNET relies on specific physical layers and integrated circuits to ensure real-time performance. | Component | Description | Function | | :--- | :--- | :--- | | **ASIC (Master/Slave)** | Specialized Communication ICs (e.g., JL-series). | Handles the protocol stack and synchronization at the hardware level. | | **Pulse Transformer** | Magnetic isolation component. | Provides electrical isolation between the bus and the internal logic to prevent noise interference. | | **RS-485 Transceivers** | Differential signaling hardware. | Converts internal TTL logic levels to differential signals for long-distance transmission. | | **Shielded Twisted Pair** | High-quality cabling (impedance ~100Ω). | Minimizes EMI (Electromagnetic Interference) and ensures signal integrity. | --- ## 2. Hardware Interface Specifications MNET is based on a high-speed, half-duplex serial communication standard. The electronic characteristics are optimized for the "Master-Slave" architecture. ### Physical Layer Details: * **Transmission Rate:** Typically **10 Mbps** or **20 Mbps** (MECHATROLINK-II) and up to **100 Mbps** (MECHATROLINK-III/IV). * **Max Stations:** Supports up to 30 or 62 slave stations depending on the specific ASIC version. * **Topology:** Bus or Star topology using specialized connectors (usually I/O style or RJ45 for later versions). ### Electronic Synchronization: Unlike standard Ethernet, MNET uses a hardware-based **Cycle Time** (typically 0.25ms to 4ms). The ASICs ensure that all motor drives receive command data at the exact same microsecond to prevent axis misalignment. --- ## 3. Communication ICs (The "Heart" of MNET) If you are designing a board for MNET, you must integrate Yaskawa-licensed ASICs. These chips manage the physical and data link layers: 1. **JL-065/JL-100:** Common master-side controllers for PLCs and Motion Controllers. 2. **JL-080:** Standard slave-side IC used in AC Servo Drives and I/O modules. 3. **Buffer RAM:** High-speed SRAM integrated into the ASIC to store cyclic command/response data. --- ## 4. Signal Wiring and Noise Suppression Because MNET operates in electrically "noisy" environments (near high-voltage motors), the following electronic precautions are mandatory: * **Terminating Resistors:** A 100Ω or 120Ω resistor must be placed at the end of the bus to prevent signal reflection. * **Common Mode Chokes:** Often added to the power lines of the MNET interface to filter out switching noise from VFDs. * **FG (Frame Ground):** Specific grounding terminals on the electronic interface to drain static and surge currents.