Mini USB 2.0 to RS-232 DB-9 Serial Adapter w/ 15kV ESD Protection & 3ft. USB Extension Cable

RS-232 | 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 Mini USB to Serial Adapter also offers 15kV surge protection for connected devices.
  • Upstream: 1 USB port, Type A Male Connector
  • Downstream: 1 Male DB9, w/ nuts
  • RS-232 Signals: DCD, RxD, TxD, DTR, GND, DSR, RTS, CTS, RI
  • Transmit Buffer: 256 Bytes
  • Receive Buffer: 128 Bytes
  • LEDs: TX / RX


(23 customer reviews)

In stock

Volume Pricing

Units Discount Price
1 - 4 $25.95
5 - 11 3 % $25.17
12 - 24 5 % $24.65
25 - 49 7 % $24.13
50+ 10 % $23.36

Also available from:

Model No. USBG-232MINI


Mini USB RS-232 serial adapter banner

Mini USB RS-232 Introduction:

The USBG-232MINI serial adapter uses a Mini USB RS-232 format to synchronize your Handhelds, Digital Cameras, or other device currently using a serial port and works with your legacy serial connections. Connecting your serial devices to the newer computer equipment using USB bus technology gives you an advantage of adding one or more serial devices when needed. This  adapter is hot plug compatible via its USB connector. The USBG-232MINI Mini USB RS-232 Serial Adapter is great for newer technologies with no serial port connections.

The high-speed DB-9 serial port with the 128 byte FIFO allows for high-speed communication between devices, even in heavy loaded systems. One of the unique features of this adapter is reduction of the system load. The serial port also allows unusual speed settings like 500.000bps. The USBG-232MINI also comes with a 3 foot USB Extension cable!

Mini USB RS-232 Features:

  • Adds one RS-232 serial port by connecting to a USB port.
  • Includes 3 foot USB extension cable.
  • Compact size cable type converter with cable length of 25 cm
  • Installed as standard Windows COM port
  • Full RS-232 modem control signals and hardware/software flow control
  • Transmit Buffer: 256 bytes
  • Receive Buffer: 128 bytes
  • RS-232 data signals: TxD, RxD, RTS, CTS, DSR, DTR, DCD, RI, GND
  • High speed serial port with the baud rate up to 921.6K bps
  • Non-standard baudrates supported
  • LED status indicators for TxD and RxD for easy port monitoring and diagnostic
  • Serial port protected with ESD protection of 15kV
  • Powered by USB port, no external power adapter required
  • Easy plug and play installation and RS-232 device connection
  • COM port number assigned can be changed to any COM port number required
  • Works with USB 1.1 & 2.0 host port
  • Dimensions: (Adapter only) 65.50mm(L) x37.10mm(W) x 18.80mm(H)

OS Support:

  • Windows Windows 7,8, 10, and 11
  • Linux and Mac OS 10.X
  • Note: As of June 2018 Windows XP is no longer supported. Please contact us if you require Windows XP support.

Package Contents:

  • Mini USB 2.0 to RS-232 DB-9 Serial Adapter
  • 3ft. USB Type-A Male to Type-A Female Cable

Compatibility List:

GPS / Chartplotters / Fish Finders:

  • Magellan Sportrak GPS
  • Garmin GPS III Plus
  • Garmin eTrex Legend
  • Garmin 76S GPS
  • Garmin Rino 120
  • Garmin Etrex
  • Garmin GPS V
  • Peets weather station
  • Sky Caddie
  • SkyCaddie SG2 Golf GPS
  • Humminbird 767
  • Megellan MAP330


  • Oregon Scientific WMR-968
  • La Crosse WS-3610
  • Davis Vantage Pro II weather station


  • Yaseu FT-950 Amateur Radio
  • Kenwood TM-D710 ham radio
  • TenTec RX320 shortwave radio receiver
  • Kenwood TM-D710 dual band Amateur radio

Routers:     (Connects to Cisco Console cable)

  • Cisco 871
    Cisco 2900/3900 XL
    Cisco ASA5505
    Cisco 678 DSL
    Cisco 2621XM


  • US Robotics Courier dual standard V.34
  • Zoom 56k external fax modem

Embroidery Machines:

  • Bernina 180 embroidery machine

OBDII Data Analyers:

  • Innova 3140 / 3160 OBD2
  • Equus 3130 Innova Diagnostic Code Scanner
  • Autel MaxiDAS

Telescopes / Solar Controllers:

  • TS-60 Morningstar Solar Controller
  • Celestron 5SE Telescope
  • Celestron CGEM astronomy tracking mount


  • Uniden BCD396XT programmable radio
  • Uniden 780XLT scanner
  • Uniden Bearcat BC346XT scanner

Stenograph Writers:

  • Stentura 200SRT
  • Stentura 400SRT
  • Stentura 500
  • Stentura 6000
  • Stentura 6000LX
  • Stentura 8000
  • Stentura 8000LX
  • WAVE


  • Brother wire EDM machine
  • Graphtec plotter

MegaSquirt car tuning
SBC ALIX Firewall
Lynx6 AL5B robot arm (Karmic RC) Matlab 2009b
Pelouze scale
DVDO iScan Duo

CNC Machines:

  • Strippit HECC80-3 CNC

Suunto X6HR watch
Altec Digitizer Tablet
Data Logging Digital Multi-meter
Conext uninterrupted power supply
Automation System SLC 500
Keile Micro Controller
SEL-751A relays (needs null modem adapter & acselerator software )
URC remote controls MX-850
Summa Graphics D15 vinyl cutter


  • Anthem MRX 300 A/V receiver
  • Anthem MRX 500 receiver
  • NuVo music system

APRS unit (Byonics RTG
iRobot Create
FreeScale Codewarrior
Technological Arts Adapt9S12C32 MCU
X10 CM11A
Crestron programmer
Zebra Label Printers


Product Specifications

Power Source

USB Connector

External Power Required


Country of Origin


Physical Characteristics


Item Dimensions (L × W × H)

2.57 × 1.46 × 0.74 in.


1 Serial Port

Material of Construction


Screw Lock Compatible


Serial Attributes
RS Signals


Serial Standards


Baud Rate

921.6K bps

FIFO Receive

128 bytes

FIFO Transmit

256 bytes

Data Bits

7, 8


None, Even, Odd, Mark, Space

Stop Bits

1, 2

Flow Control

Hardware (RTS, CTS), XON/XOFF

Serial Ports


OS Support

Win 11, Linux, Mac OSX, Win 10, Win 7, Win 8

Operating Temperature

0°C to 55°C (32°F to 131°F)

Storage Temperature

-20 to 75°C (-4 to 167°F)


5% ~ 95% (non-condensing)

Product Information

1 year from date of purchase



LED Indicators


Performance & Safety
ESD Protection

15KV Surge Protection

Max Data Transfer Rate


Ethernet Compliance
Other Data

DB9 Male w/ Nuts

Chip Model


USB Interface

USB 2.0




.2 lbs


3 × 2.5 × .6 in

UPC: 729440625108

DB9 RS-232 Pin-Outs

DB9 RS-232 Pin-Out Diagram
DB9 RS-232 Pin-Out Chart
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!

  • How do I clean and reinstall my FTDI drivers?
      1. Download the CDM Uninstaller HERE.
      2. Extract the zip file, or open the “CDMuninstallerGUI.exe” utility.
      3. Leave the ‘Vendor ID’ set to 0403 and ‘Product ID’ set to 6001.
      4. Click Add.
      5. Click Remove Devices.
      6. 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?
      1. Click on Start and navigate to the Control Panel
      2. Locate and click on Device Manager
      3. Under “Ports (COM & LPT)” you will find your serial device titled “USB Serial Port” along with its current COM Port.
      4. Right click on “USB Serial Port” and click on Properties.
      5. Navigate to the “Port Settings” tab and click on “Advanced…”
      6. Once there, the “COM Port Number:” can be changed with a dropdown menu to select the port number.
      7. Click your desired port number (i.e. COM2) and click “OK”.
      8. Click “OK” once more.
      9. 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?
    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.
    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?
    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.
    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.

  • I am receiving an error when I try to install the drivers in Windows 10 64 bit.
    Driver Signature Enforcement in Windows 10 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. Click the Windows icon in the taskbar.
    2. Click Power.
    3. Press and hold the Shift key and click Restart.

    After your computer 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.

  • Why did the software not install properly in macOS High Sierra (10.13) or later?
    High Sierra 10.13 and later versions of macOS enforce strict security policy revisions. In order for the device to operate, software packages like those used in this installation must be allowed in macOS Security and Privacy settings once the software is installed.

    Once the driver/software is installed, follow these steps to allow the software:

    1. Open System Preferences.
    2. Open Security & Privacy.
    3. Click the Allow button near the bottom of the General tab.
Reviews (23)

23 reviews for Mini USB 2.0 to RS-232 DB-9 Serial Adapter w/ 15kV ESD Protection & 3ft. USB Extension Cable

  1. H. Raymond “breadvan”

    Quality product with a nice build quality, driver installation went smoothly on my Windows 7 x64 notebook. Will buy from manufacturer again.

  2. Steve in DFW Texas

    Plugged it into my system and it has worked like a champ.

    Before you use the adapter you’ll want to run “Windows Update” off the Start menu. For Windows 7 you won’t need the mini CD-ROM that comes with the adapter. Run “Windows Update” two separate times because there are two things Microsoft wants to install.
    – FTDI – Other hardware – USB Serial Port
    – FTDI – Other hardware – USB Serial Converter

    After those two software updates are installed you’re ready to use the adapter.
    This unit also came with a very nice shielded USB extension cable too. I’m using it for a very old Garmin GPS device. The Garmin software found the serial port very easily.

  3. tmanners

    This serial usb adapter that has the FTDI chipset. The Prolific chipset adapters do not work as well as these. This worked the first time I pluged it in perfectly. If you are having trouble with the prolific chipset adapters, buy this one. I don’t give 5 stars much, but this one is a 5 star item! The price is a little high, but the free shipping makes up for it!

    The drivers on the CD it came with i’m sure are fine, but they may be 1 rev behind. I got the latest from the main website.

  4. H. Direen

    I tried 3 or 4 other manufactures of USB to RS-232 adapters and all had issues with the software I was developing. Some USB to RS-232 adapters even blue-screened Windows. This is the only adapter that worked flawlessly. The USBGear device uses the FTDI chipset and has certified Windows drivers. I highly recommend this USB to RS-232 serial adapter.

  5. electriccafe

    There’s a driver CD but it does NOT include Windows-7..

    Turns out the CD is still useful.. upon insertion a web page pops up with local driver links AND a weblink to newer drivers at [..]. Meantime the CD plays a little video explaining how to install the adapter and configure COM port settings. Pretty nice!

    You don’t need to save the CD since the adapter says ‘USBGEAR’ right on it, so you’ll always know where to get drivers.

    5 stars for a nice gadget with good back end support!

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Product Documentation & Drivers

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

Optional Accessories

Optional Accessories

The 4 port USB 2.0 USB Hub has certain accessories that work with it. These hub accessories are what you can order if needed for this hub.

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


In stock