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For shipping to USA, Canada and Mexico only. Please send inquiries to for the rest of Americas.
Please visit for other regions.
For shipping to USA, Canada and Mexico only. Please send inquiries to for the rest of Americas.
Please visit for other regions.

USB to RS232 adapters w/Optical Isolation (FULL SPEED)

SKU ES-U-1101-MB

The ES-U-1101-MB Optically Isolated USB-RS232 Adapter makes it easy to add an RS232 port to your computer. The unit connects to a USB port for quick and simple installation and is powered by the USB port with no external power supply needed.

The isolation circuit provides an optical barrier between your computer and the RS232 device connected to the unit, protecting the computer from harmful spikes and surges. The unit also features built-in surge protectors to further protect against spikes, surges and electrostatic discharge which may occur on the RS232 side.

The unit features a robust metal enclosure with mounting ears. An optional DIN rail bracket also allows mounting to DIN rails.

The unit also has LEDs for Power, Transmit Data and Receive Data which indicate the status of the unit and provide easy diagnostics.

With simple installation and a range of protection features, the ES-U-1101-MB provides an ideal solution for adding a reliable & fast RS-232 port for applications where noise and spikes may occur. 


  • Based on the renowned FTDI FT231X USB-Serial chipset and drivers
  • Microsoft Windows® WHQL-certified, macOS, Linux and Windows CE device drivers
  • 2000V DC Optical Isolation between the USB and RS232 interfaces
  • 25kV Surge Protection on the RS232 port
  • RS232 signals: TxD, RxD, RTS, CTS, DSR, DTR, DCD, RI, GND
  • Automatic Hardware (RTS / CTS) and software (X-on/X-off) flow control
  • RS232 port can appear as a Virtual Com Port allowing easy use with existing application programs
  • RS232 port can alternatively be accessed using the FTDI D2xx DLL functions
  • RS232 via DB-9 Male connector
  • Compact and robust metal enclosure
  • Power LED and Transmit and Receive LED indicators help to confirm operation and assist in troubleshooting
  • Powered from the USB port (no external power needed)
  • USB 2.0 Full-Speed (compatible with all USB ports including USB3)
  • -40°C to +85°C extended operating temperature range
  • CE / FCC approved
    Part Number  Document Type Version File
    USB to Serial Converters Manual 2.2
    ES-U-1101-M Product Change Notification (PCN) Download
    All Products Drivers Installation Guide 1.0 Download

    Download Virtual COM Port (VCP) Drivers for Windows, Mac OS and Linux

    Order Information
    SKU Ports Housing



    Updated version from ES-U-1101-M [USB-COM-Si-M] to support higher data throughput)

    Din Rail Bracket (DR-201) the rank mount clip is available for sales. If required, please contact us at

    1 Metal USB-B  w/Isolation