Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter

Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter - Image 2

Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter - Image 3

Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter - Image 4

Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter - Image 5

Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter - Image 7

Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter - Image 8

View Product Documentation, CADs, & Downloads

Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter

Model No. USB-COMi

RS-422 | RS-485 | 128 Bytes Receive | 256 Bytes Transmit | FTDI

Expand Your Serial Capabilities: The Mini Serial Adapter can be utilized through an existing USB Port to work with your legacy serial connections. It’s great for newer technologies with no serial port connections.
Safe Connections: Designed with a unique system load reduction feature, the USB to Serial Adapter also offers 15kV surge protection for connected devices.
Upstream: 1 USB port, Type B Female Connector
Downstream: 1 Male DB9, w/ nuts
RS-422 Signals: TxD-, TxD+, RxD+, RxD-, GND, RTS-, RTS+, CTS+, CTS-
RS-485 Signals: TxD-, TxD+, RxD+, RxD-, GND
Transmit Buffer: 256 Bytes
Receive Buffer: 128 Bytes

$91.29

Model No. USB-COMi

Expected Availability Date: October 30, 2026

Not in stock - Backorder allowed

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Product Documentation

FTDI Drivers

FTDI Drivers

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Description

Introduction

The Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter enables seamless communication between industrial RS-422 and RS-485 serial devices and a computer via a USB 2.0 port. This adapter is designed for environments that require reliable serial communication and efficient port expansion, making it an essential tool for system integrators, industrial automation professionals, and engineers needing high-speed data transfer in resource-constrained systems. With built-in direction control on RS-485 and Windows-native recognition as a standard COM port, it simplifies connectivity and management.

The Single USB to RS422 Serial Port Adapter with the 128 byte FIFO allows high-speed communication, even in heavy loaded systems or systems without native COM port access, unique features reduce the system load. The serial port adapter also allows unusual speed settings like 500.000bps.

RS-422 & RS-485 Mode Block Configuration SW (DIP Switch) for Mode Setting

	Operation Mode	S1	S2	S3
RS-422	4 wire with Handshaking	ON	ON	ON
RS-485	Full Duplex (4 wire)	OFF	ON	ON
	Half Duplex (2 wire) – with Echo	OFF	OFF	ON
	Half Duplex (2 wire) – without Echo	OFF	OFF	OFF

Key Features and Benefits

RS-422/RS-485 Support: Provides one RS-422/485 port with DB-9 male connection for flexible, robust serial communication.
Automatic Data Flow Control: RS-485 communication automatically handles data direction, reducing the need for software management.
High-Speed Data Transfer: Supports baud rates from 300bps to 921.6Kbps, with an additional unique speed setting of 500,000bps.
FIFO Buffering: Features a 128-byte FIFO buffer, ensuring smooth high-speed communication even in heavily loaded systems.
Visual Indicators: Built-in LEDs for transmit (TxD) and receive (RxD) provide clear, real-time communication status feedback.
Cross-Platform Compatibility: Compatible with Windows 7, 8, 8.1, 10, 11, Linux, and Mac OS X, ensuring easy integration across systems.

Package Contents

RS422/485 Single port adapter
Manual
Driver CD
USB-COMi
3ft USB A to B Cable

Use Cases

Use Cases:

Industrial Automation

Machine Monitoring: Connect serial-based sensors and controllers for real-time monitoring.
Factory Communication: Facilitate seamless data exchange between control systems and machinery.

Data Acquisition

Environmental Monitoring: Capture and log data from RS-422/485-enabled monitoring devices.
Lab Equipment Integration: Interface with lab devices using RS-422 or RS-485 protocols.

Network Communication

Remote Device Management: Enable communication between networked RS-485 devices and central management systems.
Building Automation: Connect HVAC systems, security controls, and other building management infrastructure.

Quick Specs

Quick Specs:

Hardware Specifications

Ports: One RS422/485 port
Connectors: one DB9 male
RS422/485 signals RS422 TxD+/-, RxD+/-,
RTS+/-, CTS+/-, GND
RS485 Data+/-, GND
Baud Rate: from 300bps up to 921.6Kbps supported
Transmit(TxD) and Receive(RxD) LEDS on unit for visual reference
Universal Serial Bus(USB) port offers easy plug and Play Operation

Data Signals Supported:

RS-422 data signals: TxD-, TxD+, RxD+, RxD-, GND, RTS-, RTS+, CTS+, CTS-
RS-485 4-wire data signals: TxD-, TxD+, RxD+, RxD-
RS-485 2-wire data signals: Data-, Data+

OS Support:

Windows 7, Windows 8, 8.1, Windows 10, and Windows 11
Linux and Mac OS 10.X

Ordering Information

Product Name USB-COM-I
Packing list USB-COM-I Adapter
USB cable 0,9m
CD, English Documentation
Bus-powered. No external power supply needed.

Pin-Out

DB9 RS-422 Pin-Outs

DB9 RS-485 Half-Duplex Pin-Outs

DB9 RS-485 Full-Duplex Pin-Outs

Specifications

Product Specifications

Power	Adapter Power: USB Bus Powered Power Source: USB Connector Bus Power Support: N – External Power Required
Compliance	Country of Origin: Taiwan Certifications: TAA, CE, FCC, REACH, RoHS
Physical Characteristics	Color: Blue, Gray Item Dimensions (L × W × H): 3.3 × 2.87 × 1.62 in. Item Weight (Oz.): 0.181 lbs. Ports: 1 Serial Port Material of Construction: Plastic Screw Lock Compatible: Yes
Serial Attributes	RS Signals: CTS, GND, RTS, RXD+, TXD+ Serial Standards: RS422, RS485 Serial Baud Rate Maximum: 921.6 Kbps FIFO Receive: 128 bytes FIFO Transmit: 256 bytes Data Bits: 7, 8 Serial Parity: None, Even, Odd, Mark, Space Stop Bits: 1, 2 Flow Control: Hardware (RTS, CTS), XON/XOFF Serial Port qty: 1
What's in the Box	Package Contents: Driver/Software Disk, USB Cable, USB Serial Adapter
Software	OS Support / Compatibility: Windows 11, Windows 10, Windows 8, Windows 7, Windows Vista, Windows XP, Mac OS, Linux
Environmental	Operating Temperature Range: 0C ~ 55C Storage Temperature: -20C ~ 75C Humidity: 5% to 95% RH
Product Information	Warranty: One Year
Hardware	Chipset: FTDI LED Indicators: TX / RX
Performance & Safety	ESD Protection: 15kV Max Data Transfer Rate: 12Mbps
Additional Details	UPC: 729440690861 Connector: DB9 Male w/ Nuts Chip Model: FT231XQ-R, MAX3089E USB Specification: USB 2.0 (480Mbps) Weight: 0.6500 lbs Dimensions: 4 × 4 × 2.25 in

UPC: 729440691448

Downloads

Windows FTDI Driver
Compatible with Windows XP, Vista, 7, & 8

Accessories & Replacement Parts

The RS422/485 single port serial adapter has certain accessories that work with it. These accessories are what you can order if needed.

Out of stock

Serial Cable RS232 DB9 Male to Female 5ft

RS232 Male to Female Serial Data Cable Complete your serial data connection with this 5ft. RS232 DB-9 Male to Female data cable for fast reliable…

Model# 9DBMF5FT

$2.99

Out of stock

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Need drawings, CAD files, or other compliance documentation? Click HERE

Serial F.A.Q.

Product F.A.Q.

View frequently asked product questions below. For all serial troubleshooting, visit this page.
Still need help? Reach out!

Do these adapters require an external power supply?
Most of our single and dual-port models are USB bus-powered. High-density rackmount models (8-port+) feature integrated or external power supplies for maximum signal integrity.
What is the difference between an isolated and non-isolated serial adapter?
Isolated adapters use optical barriers to physically separate the electrical signals. This protects your computer from 2,500V surges and ground loops common in factory environments.
Can I use these adapters with Windows 11?
Yes, all Coolgear Serial adapters use modern FTDI or Silabs chipsets with WHQL-certified drivers for full Windows 11, Mac, and Linux support.
What is COM Port Retention and why do I need it?
COM Port Retention ensures that your assigned COM port number remains the same every time you plug in the adapter or reboot your PC. This prevents software communication errors and eliminates the need to manually reconfigure your application settings whenever hardware is moved.
How do I clean and reinstall my FTDI drivers?
View Answer
1. Download the CDM Uninstaller HERE.
  
  Extract the zip file, or open the “CDMuninstallerGUI.exe” utility.
  
  Leave the ‘Vendor ID’ set to 0403 and ‘Product ID’ set to 6001.
  
  Click Add.
  
  Click Remove Devices.
  
  Download the corresponding driver for your operating system and follow on-screen prompts. Windows Driver | MacOS Driver
Video tutorial here.
How can I change my device’s COM port?
View Answer
1. Click on Start and navigate to the Control Panel
  
  Locate and click on Device Manager
  
  Under “Ports (COM & LPT)” you will find your serial device titled “USB Serial Port” along with its current COM Port.
  
  Right click on “USB Serial Port” and click on Properties.
  
  Navigate to the “Port Settings” tab and click on “Advanced…”
  
  Once there, the “COM Port Number:” can be changed with a dropdown menu to select the port number.
  
  Click your desired port number (i.e. COM2) and click “OK”.
  
  Click “OK” once more.
  
  Your serial device is now assigned to your chosen COM Port.
How do I check to ensure the COM port is listed properly in Windows?
View Answer
To ensure your serial device is installed properly, complete the following:
1. Press Windows Key + R to open the Device Manager. Once Run comes up, type “devmgmt.msc” into the text field and press Enter.
2. Expand the section labeled, Ports (COM & LPT).
3. You should now see a COM number in brackets to the right of each port. If the device is installed properly, no exclamation points or question marks should be present next to the device.
I have everything hooked up, but nothing is functioning correctly.
View Answer
To rule out potential issues, quickly test your individual components to ensure that they are working correctly individually, and are not the source of the problem:
- Serial cables
- Serial ports
- Serial devices
Test your components by:
- Hook up the serial cable(s), serial port(s), and serial device(s) in a different setup to see if the issue stems from a particular component, or the setup as a whole.
- Replace the serial cable, port, or device within your setup to further troubleshoot the issue’s origin.
When testing cables:
- Test each cable individually.
- Use short cables when you are testing.
When testing serial ports and devices:
- Press the Windows key + R, in Run, type devmgmt.msc, and press Enter to open the Device Manager. You can then check to see if your device is listed under Ports (COM & LPT).
- Ensure that the COM port number is the correct number for the serial device and that the software being used to connect the computer to the serial device uses the correct COM port number.
- If the device is listed with an error, follow the instructions on the website to reinstall the drivers.
Serial communication is not functioning correctly, how can I tell if the problem caused by the adapter or my serial software application?

View Answer
Older serial communication applications make use of legacy hardware addresses, often incompatible with PCI, PCIe, and USB to Serial products. Contact the software provider to troubleshoot.
I am receiving an error when I try to install the drivers in Windows 8 64 bit.
View Answer
Driver Signature Enforcement in Windows 8 may need to be disabled in order to use various drivers. After disabling this feature, the driver will be allowed to install.

Note: You are required to restart your computer after disabling the Driver Signature Enforcement. Save all open work on your computer.

Disable driver signature enforcement:
1. Press the Windows key + C.
2. Click Settings > Change PC Settings.
3. In the left pane, click General.
4. In the right pane, under Advanced startup, click Restart now.
When your system restarts:
1. Click Troubleshoot > Advanced options > Startup Settings > Restart.
2. Press 7.
When your computer restarts, Driver Signature Enforcement will be disabled and you can install the drivers.

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Single Port USB 2.0 to RS-422 / RS-485 DB-9 Serial Adapter

RS-422 | RS-485 | 128 Bytes Receive | 256 Bytes Transmit | FTDI

Product Documentation

FTDI Drivers

Quick Links:

Description

Introduction

Key Features and Benefits

Package Contents

Use Cases

Use Cases:

Industrial Automation

Data Acquisition

Network Communication

Quick Specs

Quick Specs:

Pin-Out

DB9 RS-422 Pin-Outs

DB9 RS-485 Half-Duplex Pin-Outs

DB9 RS-485 Full-Duplex Pin-Outs

Specifications

Product Specifications

Downloads

Accessories & Replacement Parts

Accessories & Replacement Parts

Support

Product Documentation & Drivers

Product Documentation