Melsec Serial (Mitsubishi)
Melsec Serial
The Melsec Serial driver is used to communicate with Mitsubishi FX Series PLCs (FX1S, FX1N, FX2N, FX3U, etc.) or Q Series C24 modules over Serial Ports (RS232/RS422/RS485).
Connection Settings (Network Settings)
These settings must match the “Serial Communication Settings” (or DIP-switch configuration) on the PLC exactly.
| Parameter | Description | Example |
| Serial Port | The COM port on your computer to which the PLC is connected. | COM1 |
| Baudrate | Communication speed (9600, 19200, 38400, 115200). Standard values for FX series are usually 9600 or 38400. | 9600 |
| Parity | Parity bit (None, Odd, Even). FX series commonly uses Even. | Even |
| Stop Bits | Number of stop bits (One, Two). | One |
| Data Bits | Number of data bits (7 or 8). FX series typically uses 7 bits. | 7 |
| Delay (ms) | Used to prevent data collisions on the serial line. | 100 |
| Timeout (ms) | Increase for older cables or low-speed communication. | 250 |
| Retry Count | Retries before marking the device as “Fault”. | 3 |
Station (Device) Settings
This panel defines the PLC’s identity and read limitations on the serial network (RS232/RS422/RS485).
| Parameter | Explanation and Usage |
| Address | Station Number: • RS232/422 (Point-to-Point): Typically set to 0. • RS485 (Multi-drop): Each PLC must have a unique station number (configured in PLC parameters). |
| Symbol | Symbolic name assigned to the device (e.g., Device). |
| Enable | Determines whether the device is active. You can define conditional expressions to enable/disable communication dynamically. Multiple enable conditions may be added; if any condition is true, the device becomes active. Leave empty to always enable. |
| Skip After Failure | Recommended to set True. If the device does not respond (Timeout), other tags for this device are skipped, preventing slowdowns—especially useful in RS485 networks when a device is powered off. |
| Maximum word count | Packet Size: The maximum number of Words (registers) read in a single request. Default is 125. Note: For older FX PLCs or noisy lines, reducing this value (e.g., to 32 or 64) may improve stability. |
| Connected | The selected bit becomes “True” when communication is established. |
| Fault | The selected bit becomes “True” when a communication error occurs. |
| Comment | Optional device description. |
Addressing Table
Wise SCADA uses the following prefixes for Mitsubishi PLC memory areas.
- Important Note (Hex vs Decimal):
In Mitsubishi addressing:
- Physical I/O such as X and Y are Hexadecimal (e.g., X0, X1 … XF, X10).
- Memory areas like M and D are Decimal (e.g., M0, M100, D0).
| Address Type | Data Type | Description | Example |
| M | Bit | Internal Relay | M 0, M 100 |
| X | Bit | Physical Input – Hex | X 0, X 1F |
| Y | Bit | Physical Output – Hex | Y 0, Y 10 |
| B | Bit | Link Relay – Hex | B 0, B 1A |
| D | Word (16-bit) | Data Register | D 0, D 100 |
| W | Word (16-bit) | Link Register – Hex | W 0, W 1F |
| R | Word (16-bit) | File Register | R 0, R 50 |
| ZR | Word (16-bit) | Extended File Register | ZR 0, ZR 100 |
| L | Bit | Latch Relay | L 0, L 50 |
| F | Bit | Fault (Annunciator) Relay | F 0, F 10 |
| TN / CN | Word | Timer / Counter (Current Value) | TN 0, CN 5 |
| TS / CS | Bit | Timer / Counter (Contact Status) | TS 0, CS 5 |