The FX2N-422-BD is Mitsubishi Electric’s RS-422 communication option board for the MELSEC FX2N compact PLC series, providing a second RS-422 full-duplex serial communication port — primarily used for connecting a second Mitsubishi GOT HMI panel or GX Works2 programming station via RS-422 when the built-in RS-422 port is already occupied by another device, or for long-distance RS-422 serial communication with devices requiring balanced differential signalling for improved noise immunity over distances up to 50 m. The FX2N-422-BD is available through Atlantech Drives — quote within 24-48 hours, worldwide express shipping, 12-month warranty.
What Is the FX2N-422-BD?
The FX2N-422-BD is a communication option board installing in the FX2N base unit’s option board slot, providing an additional RS-422 full-duplex port with a 9-pin D-Sub female connector for Mitsubishi FX communication protocol, GX Works2 programming, and GOT HMI panel connection. RS-422 uses balanced differential signalling (±2V differential swing) providing superior noise immunity compared to RS-232C (±12V single-ended) over cable distances up to 50 m — the intermediate distance capability between RS-232C’s 15 m and RS-485’s 500 m. The FX2N-422-BD’s primary application is providing a second RS-422 communication port for FX2N systems that must simultaneously connect to two Mitsubishi GOT HMI panels, or for systems where the built-in RS-422 port is used for programming access and an additional RS-422 port is needed for a permanently connected HMI panel. Unlike the FX2N-485-BD which supports multi-drop networking, the FX2N-422-BD’s RS-422 port is a point-to-point connection — only one device can be connected to the FX2N-422-BD’s RS-422 port. The board uses the same Mitsubishi FX serial communication framework as the FX2N-232-BD and FX2N-485-BD, supporting Mitsubishi FX protocol, Modbus RTU slave, and free-protocol (RS instruction) communication modes.
Key Technical Specifications
- Model: FX2N-422-BD
- Interface: RS-422 full-duplex, point-to-point
- Installation: FX2N base unit option board slot (direct plug-in)
- Connector: 9-pin D-Sub female (RS-422 pinout)
- Maximum Cable Length: 50 m
- Maximum Devices: 1 (point-to-point only)
- Baud Rate: 300 bps to 19,200 bps
- Supported Protocols: Mitsubishi FX communication protocol (primary), Modbus RTU (slave), free-protocol (RS instruction)
- Signal Levels: RS-422 balanced differential (±2V minimum differential)
- Compatible FX2N base units: All FX2N models
- Power Supply: From FX2N base unit (no external supply required)
- Operating Temperature: 0°C to 55°C
- Weight: Approx. 0.05 kg
Typical Industrial Applications
The FX2N-422-BD is deployed primarily in FX2N installations requiring a second RS-422 communication port for GOT HMI panel connection when the built-in RS-422 port is already in use. In machine tool control panels where the FX2N built-in RS-422 port connects to the operator’s main GOT HMI at the front of the machine, the FX2N-422-BD’s RS-422 port provides a separate connection to a second GOT panel mounted on a pendant arm for the maintenance technician — both GOT panels access the FX2N simultaneously, each via its own dedicated RS-422 port. In food processing equipment where the FX2N communicates with a GOT panel at the operator station via the built-in RS-422 port, the FX2N-422-BD enables a remote GOT panel in the quality control office (up to 50 m away) to monitor production data simultaneously without requiring Ethernet infrastructure. The FX2N-422-BD’s 50 m cable distance capability (versus RS-232C’s 15 m limit) makes it the appropriate choice for panel-to-panel connections within the same building section — connecting a FX2N controller in a motor control centre (MCC) to a remote operator panel 30–50 m away in the process area, for example. For facilities management applications where the FX2N controls HVAC equipment and a building management system PC requires serial data access at a distance exceeding RS-232C’s 15 m limit, the FX2N-422-BD’s 50 m RS-422 capability provides the reach without the complexity of RS-485 multi-drop network configuration. In injection moulding machine control, the FX2N-422-BD provides the second serial port for a peripheral device — such as a material dryer controller or mould temperature controller — that communicates via RS-422 serial protocol, while the built-in RS-422 port handles the primary HMI connection.
Replacement & Upgrade Notes
The FX2N-422-BD is a discontinued Mitsubishi product available for maintenance replacement through specialist distributors. For FX2N systems where the FX2N-422-BD has failed and a direct replacement cannot be sourced, the communication function provided by the FX2N-422-BD can be replicated using an RS-232C-to-RS-422 converter installed between the FX2N-232-BD (if not already installed) and the connected RS-422 device — the converter handles the signal level translation, though cable distance is then limited by the converter’s specifications. For FX3U-based system upgrades replacing FX2N installations with FX2N-422-BD for HMI communication, the FX3U platform provides the same option board architecture with the FX3U-422-BD providing an additional RS-422 port for GOT HMI connection on the FX3U base unit. When migrating a complete FX2N system to FX3U, the FX3U platform’s wider communication capability (Ethernet via FX3U-ENET-ADP, CC-Link via FX3U-16CCL-M) provides alternative HMI connection options that eliminate the need for RS-422 option boards entirely — GOT2000 HMI panels support Ethernet connection to FX3U controllers via the FX3U-ENET-ADP, removing the distance limitation of RS-422 cabling. For facilities building new systems, specifying the FX5U or FX3U with Ethernet connectivity and a GOT2000 panel over LAN avoids the serial communication distance constraints entirely.
Frequently Asked Questions
Q: Can two GOT HMI panels be connected simultaneously — one to the FX2N built-in RS-422 port and one to the FX2N-422-BD?
A: Yes. This dual-GOT configuration is the primary intended use case for the FX2N-422-BD. Both GOT panels communicate with the FX2N simultaneously via their respective RS-422 ports — each GOT can read and write FX2N device data independently, display different screens, and be operated by different users at the same time. The FX2N handles the two RS-422 communication tasks concurrently via its dual serial port architecture.
Q: What is the pinout of the FX2N-422-BD’s 9-pin D-Sub connector, and is it compatible with standard RS-422 cables?
A: The FX2N-422-BD’s 9-pin D-Sub connector uses Mitsubishi’s FX RS-422 pinout, which is specific to Mitsubishi FX communication and is NOT compatible with standard RS-422 EIA pinouts or RS-232C pinouts. Use Mitsubishi FX series GT connection cables (GT-01-C30R4-6P or similar) for GOT HMI connection, or refer to the FX2N-422-BD hardware manual for the specific pin assignments when building custom cables for non-GOT devices. Using standard RS-422 cables without verifying pin compatibility against the FX2N-422-BD pinout will result in no communication or potential damage to the connected device.
Q: Can the FX2N-422-BD be used for GX Works2 programming access simultaneously with a GOT HMI connection?
A: Not simultaneously on the same port. The FX2N-422-BD’s RS-422 port supports either GX Works2 programming (Mitsubishi FX programming protocol) or GOT HMI communication (Mitsubishi FX display protocol) — both use the same communication protocol standard but the FX2N RS-422 port can only handle one communication session at a time. For simultaneous GX Works2 programming and GOT HMI access, use the built-in RS-422 port for the GOT and the FX2N-422-BD port for GX Works2 programming (via a USB-to-RS-422 cable), or vice versa, assigning each port to one communication task.
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