SystemBase Multi-8U Combo — USB to 8-Port RS422/RS485 Serial Converter Adapter

📋 Overview

The SystemBase Multi-8U Combo is a professional-grade USB to 8-port serial converter that instantly adds eight RS422/RS485 (Combo) serial ports to any Windows or Linux computer through a single USB 2.0 connection. With communication speeds up to 921.6Kbps, ±15kV surge protection on every port, and per-port TX/RX LEDs for real-time status monitoring, the Multi-8U Combo is built for demanding industrial and commercial serial communication environments.

Each port features a standard DB9 connector and can be independently configured for RS422 (Point-to-Point or Multi-Drop) or RS485 (Echo or Non-Echo) mode using convenient DIP switches — no software configuration required. The unit is USB bus-powered and includes a latching USB connector for secure, vibration-resistant connections.

⭐ Key Features

• 8 Serial Ports from One USB Connection — Adds eight RS422/RS485 Combo serial ports through a single USB 2.0 port
• High-Speed Communication — Supports data rates up to 921.6Kbps for fast, reliable serial data transfer
• Flexible RS422/RS485 Modes — Each port is independently configurable via DIP switches: RS422 Point-to-Point, RS422 Multi-Drop, RS485 Non-Echo, or RS485 Echo
• ±15kV Surge Protection — Built-in ESD protection on every port safeguards connected equipment from electrical surges
• TX/RX LEDs Per Port — Real-time transmit and receive activity indicators on each of the 8 ports for easy diagnostics
• Auto Toggling — Automatic control of bus I/O direction for RS422/RS485 communication, simplifying half-duplex setups
• Slew-Rate Limit Control — Configurable slew-rate limiting reduces EMI and signal reflections for long cable runs (limits speed to 250Kbps when enabled)
• Termination Resistor Support — Built-in 120Ω termination resistors for RS422 and RS485 can be enabled via jumper settings
• +5V Power on Pin 9 — Optional external DC adapter allows +5V power delivery through pin 9 of each DB9 connector to power connected devices
• DB9 Male or Female Serial Connectors — Available with either DB9 Male or DB9 Female serial connectors
• Latching USB Connector — Secure locking USB connection prevents accidental disconnection in industrial environments
• Plug and Play — Automatically detected by Windows and Linux — no reboot required
• USB Bus-Powered — No external power supply required for standard operation

📊 Specifications

🔧 Setup & Configuration

1. Connect the USB cable — Plug the latching USB cable into the Multi-8U Combo and connect the other end to an available USB port on your computer. You should hear a click when the latch engages.
2. Install the driver — Windows will attempt automatic driver installation. If needed, download the latest driver from the SystemBase website and install manually. Linux users should contact SystemBase technical support at tech@sysbas.com.
3. Configure each port — Use the 2-position DIP switch on each port to select your desired mode: RS422 Point-to-Point (OFF/OFF), RS422 Multi-Drop (OFF/ON), RS485 Non-Echo (ON/OFF, default), or RS485 Echo (ON/ON).
4. Set termination resistors (if needed) — Use the internal jumpers to enable the 120Ω termination resistor for RS422 or RS485 as required by your network topology.
5. Connect your serial devices — Attach your RS422 or RS485 devices to the DB9 connectors and verify communication using the TX/RX LEDs.

💡 Tip: The slew-rate limit jumper defaults to disabled (10M mode, max 921.6Kbps). For long cable runs where signal integrity is a concern, enable the 250K slew-rate limit mode to reduce EMI and reflection waves.

📌 DIP Switch Settings

📦 What's in the Box

• 1x SystemBase Multi-8U Combo (RS422/RS485) Converter - Serial connector type selected above
• 1x Latching USB Cable
• 1x Quick Start Guide

External DC power adapter is not included. Required only if supplying +5V power through DB9 pin 9.

🔌 Compatible With

• Windows 7, 8, 8.1, 10, and 11 (32-bit and 64-bit)
• Windows Server 2008, 2012, 2016, 2019, 2022
• Linux (Kernel 2.6 and above — contact SystemBase for driver support)
• Any RS422 or RS485 serial device with DB9 connectivity

🎯 Applications

• Industrial automation and SCADA systems
• POS (Point of Sale) terminal networks
• Building management and access control systems
• Data acquisition and laboratory instrumentation
• Multi-device RS485 sensor networks
• Surveillance and security system integration
• CNC machine and PLC communication
• Telecommunications equipment management

⚠️ Important Notes

• The Multi-8U Combo model supports RS422 and RS485 only. If you need RS232 ports, look for the Multi-8U RS232 model.
• An external 5V DC adapter is required to supply power through pin 9 of the DB9 connectors. Without the adapter, pin 9 does not carry power.
• When using the slew-rate limit feature (250K mode), maximum communication speed is reduced to 250Kbps.
• For Linux driver support, contact SystemBase technical support at tech@sysbas.com.
• The latching USB connector provides a secure connection — press the spring button lightly and sweep to disconnect.

📄 Documentation & Resources

• Multi-8U COMBO User Manual, Utilities and Specifications Downloads (SystemBase Website)