How to Add 4 RS422/RS485 Serial Ports to Your Mini PC with an M.2 Adapter Card

If you're working with industrial automation, SCADA systems, or embedded computing, you've likely run into a common challenge: modern mini PCs and NUCs simply don't come with RS422 or RS485 serial ports. Yet many industrial devices — PLCs, sensors, meters, and CNC machines — still rely on these protocols for reliable, long-distance communication.

The good news? You can add 4 independent RS422/RS485 serial ports to your mini PC without any external adapters or USB dongles — just by using an M.2 expansion card.

What Is an M.2 RS422/RS485 Serial Adapter Card?

An M.2 serial adapter card plugs directly into the M.2 B+M Key slot found on most modern mini PCs, NUCs, and embedded boards. Unlike USB-to-serial adapters, an M.2 card provides a stable, low-latency connection that is far more suitable for industrial environments.

The Lekuo M.2 B+M Key 4-Port RS422/RS485 Serial Adapter Card (SKU: MW84Z41) gives you 4 fully independent serial ports in a compact form factor — all from a single M.2 slot.

Key Features

• 4 Independent Ports: All 4 RS422/RS485 ports operate simultaneously without signal interference, enabling multi-device communication in parallel.
• Dual-Mode Support: Each port supports both RS422 (full-duplex) and RS485 (half-duplex), giving you flexibility to connect a wide range of industrial devices.
• Long-Distance Communication: Supports up to 1200 meters in RS485 mode — ideal for factory floors, outdoor deployments, and large facilities.
• Compact M.2 Form Factor: Fits standard M.2 B+M Key slots, making it perfect for space-constrained mini PCs and embedded systems.
• Wide OS Support: Compatible with Windows and Linux. Install the WCH CH382/CH384 chip driver and you're ready to go.

Who Is This For?

This card is designed for engineers and system integrators who need to:

• Connect PLCs, sensors, or meters to a mini PC in an industrial control cabinet
• Build SCADA or data acquisition systems with multiple serial devices
• Replace aging desktop PCs with compact mini PCs without losing serial port functionality
• Deploy embedded systems in space-constrained environments

Installation Overview

1. Power off your mini PC and locate the M.2 B+M Key slot.
2. Insert the adapter card into the slot and secure it with the mounting screw.
3. Power on your system and install the WCH CH382/CH384 chip driver.
4. The 4 serial ports will appear in your device manager, ready to use.

Typical Applications

• Industrial automation and PLC communication
• SCADA and HMI systems
• CNC machine control
• Environmental monitoring with RS485 sensors
• Smart metering and energy management
• GPS and positioning systems

Specifications at a Glance

• Interface: M.2 B+M Key
• Serial Ports: 4 x RS422 / RS485
• Communication Mode: Full-duplex (RS422) / Half-duplex (RS485)
• Max Distance: 1200m (RS485)
• OS Support: Windows, Linux
• SKU: MW84Z41

If you're looking to bring reliable industrial serial communication to your mini PC or embedded system, the Lekuo M.2 RS422/RS485 adapter card is a clean, professional solution that fits right into your existing hardware.