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Connect a RS-232 Null Modem serial device to the USB-A port on your computer, laptop or tablet.

  • Supports data transfer speeds up to 256 Kbps
  • Premium foil and braid shielding reduces EMI/RFI line noise
  • Compatible with Windows®, Mac® and Linux®
  • No external power source required
  • Integrated FTDI FT232RL chipset
  • 3-year limited warranty


Converts USB Port into RS-232 Null Modem Serial Port
  • Solves DCE/DTE conflicts without additional cross-wired serial cables or adapters
  • Supports data transfer speeds up to 256 Kbps—twice as fast as a built-in serial port
  • No external power source required
  • Portable 18 in. design fits perfectly into laptop bag
  • COM retention for automatic reassigning of COM values to ports in case of disconnection or reboot
  • Integrated FTDI FT232RL chipset

First-Rate Construction for Superior Signal Transfer
  • Premium foil and braid shielding for EMI/RFI noise protection
  • Molded nickel-plated connectors with gold-plated contacts for optimal signal quality
  • Integral strain relief for long life
  • Flexible PVC jacket easy to install in tight spaces

Broad Compatibility
  • Compatible with Windows, Mac and Linux operating systems

System Requirements

  • Computer or other device with available USB port and Windows XP or later, Mac OS X 10.3 or later, or Linux

Package Includes

  • U209-18N-NULL USB to Null Modem Serial FTDI Adapter Cable (USB-A to DB9 M/F), 18 in.
  • Driver CD
  • Owner’s manual
RoHS compliant


UPC Code037332198297
Bus Powered  Yes
Power Consumption (Watts)0.5
Number of Ports1
Side A - Connector 1USB A (MALE)
Side B - Connector 1DB9 (FEMALE)
Connector PlatingNickel
ColorBlack; Silver
Material of ConstructionPVC
Cable Jacket ColorBlack
Cable Jacket RatingVW-1
Cable Length (ft.)1.5
Shipping Dimensions (hwd / in.)1.50 x 3.70 x 4.50
Shipping Weight (lbs.)0.30
Unit Packaging TypeBox
Unit Weight (lbs.)0.07
Operating Temperature Range32° to 104°F (0° to 40°C)
Storage Temperature Range14° to 131°F (-10° to 55°C)
Relative Humidity5% to 90% RH, Non-Condensing
BTUs  1.7 BTU/Hr
USB SpecificationUSB 2.0 (up to 480 Mbps)
Driver RequiredYes
Product ComplianceRoHS; CE (Europe); REACH; WEEE; FCC (USA)
Product Warranty Period (Worldwide)3-year limited warranty

Questions & Answers

COM retention allows the same COM port number to be automatically assigned each time the serial adapter is connected to a USB port on your system (or your system is rebooted). Without COM Retention, you would have to remember which port to connect the adapter.
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