USB 2.0 RS-232 Serial Adapter 16 Inches w/ LED Indicators

(9 customer reviews)


This 16 inch USB to Serial adapter is a tool of choice when supporting serial peripherals in newer computers without serial support. Now supported by Windows 11, this is an ideal solution for device support.


  • LED activity monitoring
  • Full support of RS-232 signals
  • USB bus powered
  • 14 in. cable connection
  • Supports Windows 7, 8, 10, and 11, Linux, OSX

Product Documents

Available on backorder

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Model #: GM-FTDI-LED16 Categories: , , , Tag:

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This USB 2.0 RS-232 Serial Adapter is 16 inches long the easiest way to add a serial port to your computer. Newer computers today lack serial ports for communication; this affects PDA, digital camera, and GPS type equipment that may be used on your system. This 16 inch USB serial adapter is great for troubleshooting and allows you to add a serial port and monitor the status of your connections via LED activity flashes. When connection activity is present, the LED’s will flash letting you know you have signal on the pins.

LED Activity Lights for Diagnostics

The GM-FTDI-LED16 offers an advanced an FTDI Chipset supported by Windows 11, USB 2.0 RS-232 connection with double color LED Display of Full Signal Power. The device is powered individually by the USB 2.0 port. This 16 inch device is easily installed, it features a Plug & Play easy test RS-232 Host to Device link and is backwards compatible with USB Spec 1.1.


Package Contents:

  • USB 2.0 RS232 Serial Adapter with LED’s
  • Latest FTDI Driver (available for download)
  • GM-FTDI-LED Product Manual (available for download)


LED Color:

  • 1~4, 6~9 PIN Signal 0 : Green / Signal 1 : RED GND – RED – POWER PS. DB9-F PIN / 1,2,6,8,9 NO Input LED no light
  • Easy test RS-232 Host to Device link

OS Support:

  • Windows 7, 8, 10, & Windows 11
  • Linux, Mac OS 10.X

DB-9 Pin Assignment
Pin Data Type Input/Output LED Color
1 IN Data Carrier Detect (DCD) Green
2 IN Receive Data Receive (RXD) None
3 OUT Transmit Data (TXD) Green
4 OUT Data Terminal Ready (DTR) Green
5 GND Ground Wire Red
6 IN Data Set Ready (DSR) None
7 OUT Request Send (RTS) Green
8 IN Clear Send (CTS) None
9 IN Ringing Indicator (RI) None

Additional Features & Specifications:

Device Support:

  • Convenient 16 inch total length for troubleshooting
  • PDA RS-232 Port support 56K Modem support Serial Mouse support+ Serial PC camera support
  • Fully compliant with USB Spec 2.0 Compliant USB Spec1.1
  • RS-232 – DB9 / M Data rate : Over 1000kbps
  • ESD Protection for RS-232 I/O’ +-15KV RS-232 for DTE Mode

We’ve written a blog post on Serial Driver Support including information on Windows Operating System life cycle.

Additional information

Weight 0.131 lbs
Dimensions 8.000 × 6.000 × .75 in




Supported OS

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Cable Length




USB to RS232


1 year from date of purchase.

Tech Note

Download page contains a special note with regard to driver install.

Chip Set

Drivers & Manuals

9 reviews for USB 2.0 RS-232 Serial Adapter 16 Inches w/ LED Indicators

  1. radiojf

    5.0 out of 5 stars

    Best thing to have
    Having old school serial cable with the best thing have

  2. Mr Lobo

    5.0 out of 5 stars

    Works without driver on OSX Ventura!
    My main reason for purchasing this unt was I wanted a short cable (not 3’) and had to work in the OSX Ventura. My older Keyspan was great, but they are so slow in creating device drivers, they may never have one for a Ventura; now that kext’s are not supported by third parties

  3. Mario

    5.0 out of 5 stars

    Fine product
    Fine product to convert usb serial

  4. Gadget-Guy

    4.0 out of 5 stars

    A Bit of Overkill
    I needed a RS232 adapter that mapped a USB port to Com8.This one did.It works.The LEDs are a nice touch – though not terribly useful.If you can see a millisecond flash during communications, then they are just fluff.Should come with a RS232 for Dummies book.Summary:Worked for me.

  5. Daland Speirs

    5.0 out of 5 stars

    Works as intended
    This converter works as one would expect. The onboard LEDs help in determining communication activity and if both directions are operating, given the application at hand.

  6. David Henderson

    5.0 out of 5 stars

    Great little USB COM port, FTDI compliant
    Fast shipping and device works in all aspects. One really great feature is the clear case has an LED for each data line (TXD, RXD etc) If you trouble shooting a "system" it gives great visual clue as to whether a given data line is passing bytes as it should…wish I had this years ago would have save me countless hours

  7. Frank

    5.0 out of 5 stars

    Worked for PlusDeck 2c Windows 10 64 bit
    I installed the Gearmo 16in. USB 2.0 to RS-232 Serial Converter, went to the Gearmo website, attempted to download the drivers, but was told the latest drivers were already installed. Did the same for the CD that came with the converter and got the same message. No surprise. Typically, website drivers are the latest and greatest, so I would start there first as long as you’ve made sure you have the latest Windows updates.For me, the converter took a little time to be detected, but it was and it works great now. Maybe do a restart before you start to think its not working for you. Honestly, I haven’t relied on the indicators since the installation. Maybe you will if you have an issue. I’m just happy it works as I’ve tried other, cheaper ("less sophisticated") converters with no success. Hope this helps someone who still has a Plusdeck 2c like I do.

  8. Bill Parsons

    4.0 out of 5 stars

    USb to serial adapter
    Best one I’ve found, just wish it came with the Windows 10 drivers. Not a big deal, I downloaded them.

  9. Amazon Customer

    5.0 out of 5 stars

    Works great, no issues. Buy it.
    Works great just as described. I use for work and for programming control boards and engine ECM’s. No issues. Buy it.

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