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USB to 4 RS232/422/485 Ports

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Flexcom 4
  • Four-port serial communications adapter for USB 1.1 and USB 2.0 host ports
  • Supports field selectable RS-232, RS-422 or RS-485 protocols, per port
  • Includes type FT232BM UART with 384-byte receive/128-byte transmit FIFO buffers
  • Speeds up to 921.6kbps simultaneously
  • Power LED and individual port activity LEDs next to the USB and each COM connector
  • All required power drawn from USB port, no external power adapter required
  • Compact, low profile enclosure


  • -OEM Board only version with no enclosure
  • -HDR OEM board with 10-pin vertical male headers instead of DB9s
  • -DIN DIN rail mounting bracket
  • -RoHS Available in a RoHS compliant version.


  • Multiple POS peripherals
  • Barcode scanners
  • Scales
  • Date-entry terminals
  • Data acquisition and automation modules

This flexible serial communications adapter was designed for effective multipoint transmission in any one of three modes on each channel. These modes are RS232, RS422 and RS485 (EIA485) protocol.


The OEM (board only) version is perfect for a variety of embedded applications. What makes the OEM option unique is that its PCB size and mounting holes match the PC/104 form factor (without the bus connections). This allows our rugged USB to quad-serial port board to be added to any PCI-104 or PC/104 stack by connecting it to a simple USB port usually included on-board with embedded CPU form factors such as EBX, EPIC, and PC/104. This is especially important since many newer CPU chipsets do not support ISA and have plenty of USB ports. The USB-FLEXCOM4 OEM board can also be installed using standoffs inside other enclosures or systems.



The USB-FLEXCOM4 is available with optional cable assemblies and screw terminal adapter board ADAP9.


The USB-FLEXCOM4 is plug-and-play which allows quick connect or disconnect whenever you need additional I/O on your USB port. The USB-FLEXCOM4 is supported for use in most USB supported operating systems and includes a free Linux and Windows 98se/Me/2000/XP/2003 compatible software package. This package contains sample programs and source code in Visual Basic, Delphi, C Builder, and Visual C for Windows. Also incorporated is a graphical setup program in Windows. Embedded OS support include Windows Xpe.

flexcom block diagram

Flexcom OEM
OEM Version

Communications Interface

  • Serial Ports: COM A through COM D via four male DB9 connectors
  • Character length: 5, 6, 7, or 8 bits
  • Parity: Even, odd or none
  • Stop Interval: 1, 1.5, or 2 bits
  • Serial Data Rates: Up to 921.6k for RS-422 and RS-485 modes, asynchronous RS-232 speeds up to 230.4kbps.
  • Receiver Input Sensitivity: 200 mV, differential input
  • Common Mode Rejection: 12V to -7V
  • Transmitter Output Drive: Up to 60 mA, with thermal shutdown
  • Bus Type USB 2.0 Full-Speed
  • USB Connector: Type B, high-retention
  • Embedded USB Connector 5-pin header, Molex part number 53047 Mating connector housing is Molex part number 51021 0500 -OEM VERSION


  • Operating Temperature: 0 °C. to 60 °C
  • Storage temperature: -50 °C. to 120 °C
  • Humidity: 5% to 95%, non-condensing
  • Power Required: 5VDC at approximately 110 mA (plus loads up to an additional 240 mA) from USB bus
  • Size: Board Dimension: 3.550 x 3.775 inches (PC/104 size & mounting)
  • Box Dimension: 4.00 x 4.00 x 1.25 inches
    DB-9 Male Pin for each of Ch A-D RS-232 Signals (Industry Standard) RS-485 Signals (2 Wire) RS-422 Signals (Also 4wire RS485)
    Ch x pin 1 DCD   RX-
    Ch x pin 2 RX TX /RX TX
    Ch x pin 3 TX TX-/RX- TX-
    Ch x pin 4 DTR    
    Ch x pin 5 Gnd Gnd Gnd
    Ch x pin 6 DSR    
    Ch x pin 7 RTS    
    Ch x pin 8 CTS    
    Ch x pin 9 RI   RX

Available Reference Manuals

Available Software Downloads

Available Datasheets

Further information about available ACCES Software:

Drivers And Operating Systems
What drivers and other support we provide for various operating systems.

Setup Programs, Samples, And Utility Software
A description of the software package that comes with each ACCES card.

Redistributing Windows Drivers
A list of ACCES drivers and the files that compose them under different versions of Windows, so you can easily redistribute ACCES cards and drivers.


Model Price (USD)
USA Office

Address: 1480 Gulf Road, Suite 837,
PO Box 1364
Point Roberts, WA 98281

Western Canada - Vancouver BC

Tel:1.800.663.6001 or 1.604.925.6150
Address: 2454 Haywood Ave
West Vancouver, BC V7V 1Y1

Eastern Canada - Markham, Ontario

Tel:1.800.465.0164 or 1.905.513.7027