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USB-8COM Plus ISO (612)

Main Features

  • USB 2.0 to 8 x RS232/422/485
  • High-Speed serial ports 921.6kbps
  • Driver for Windows, Linux, Mac OS X
  • LEDs for Power and TxD/RxD activity
  • ESD protection on USB and serial ports
  • 2.5kV electrical isolation (ISO version only)
  • Self powered
  • Wide range of power input 9 - 54V DC
  • Metal housing
  • 19-inch rack and wall mounts
  • Wide range of operating temperatures

VScom USB-8COM Plus, an octal port USB-to-Serial adapter for RS232/422/485



Quick Link: | Main Features | More Pictures | Overview | USB Interface | Serial Interface | Serial Port Expansion | Software | Power Requirement | Housing and Mounting | Environmental Data | Standards and Certifications | MTBF (Mean Time Between Failures) | Warranty | Ordering Information | Options | Packaging | Download |


  More Pictures

VScom USB-8COM Plus, an octal port USB-to-Serial adapter for RS232/422/485              
Click on the thumbnails to enlarge them …

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The USB-8COM Plus provides easy serial port expansion over USB 2.0 connecting to high speed RS232 or RS422/485 devices. The device is fully ESD and surge protected, bus powered and accommodated in a ruggedized metal housing. Furthermore, it can operate across a large range of temperature levels to cope with harsh operating conditions. The ISO version is 2.5kV electrically isolated to withstand unbalanced ground loops that arise in hazardous industrial environment. Lastly, both DIN-Rail and wall-mounting options are available.

Flexible Three-Way Serial Ports

The serial ports allow different operating modes — which are easily configured via a single DIP switch — to fully support RS232, RS422 and RS485 protocols. The operating mode of serial ports chosen via DIP switch is either same for all ports or individually for each port by "USBCOM Configuration Utility" software. The differential line termination for RS485 (120Ω) is automatically controlled by choosing the appropriate operating mode. High/Low biasing resistors are not needed; as such, hassle-free usage is guaranteed for the user.
Com Port drivers are available for Windows, Linux and Mac OS X. A configuration tool allows easy access to special Windows driver options.

High Speed and Isolation

USB 2.0 High Speed connection allows serial data rates of up to 12Mbps for RS422/485 and 921.6kbps for RS232. Every non-standard bitrate (e.g. 500kbps) can easily be set up in the range of up to 3.5Mbps.
USB-xCOM Plus adapters are 16kV ESD and surge protected at USB and serial ports interfaces. Additionally, the serial ports are 2.5kV electrically isolated (ISO version only), making them ideal for deployment in harsh industrial environments.

Power and Port Expansion

Multiple USB-xCOM Plus devices can be concatenated via the USB Type A at the rear side, creating up to 32 serial ports. In concatenated configuration, the local power input of each expansion module must be used.
USB-xCOM Plus 4 and 8 ports adapters can also be used to expand the serial ports for NetCom Plus Servers (4 and 8 ports).

  USB Interface


USB 2.0 High Speed, USB 1.1 compliant


USB type B


Genesys GL850G

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  Serial Interface

No. of Ports/Type

8 x RS232/422/485 configurable by DIP switch and software


DB-9 male


  • 16kV ESD surge protection
  • 2.5kV Electrical isolation on ISO version

Operating Modes

  • RS232
  • RS422 full duplex              (120Ω on/off)
  • RS485 4 wire, full duplex    (120Ω on/off)
  • RS485 2 wire, half duplex   (120Ω on/off)


The single DIP switch at rear side configures all ports in the same operating mode or individually via software:

  • Windows: using "VScom USB Configurator" Utility
  • All OS: using Terminal emulation
The operating mode controls termination.
No High/Low biasing resistors needed

Signals non-ISO

  • RS232: TxD, RxD, RTS, CTS, DTR, DSR, DCD, GND
  • RS422: Tx+/-, Rx+/-, GND
  • RS485 4-wire: Tx+/-, Rx+/-, GND
  • RS485 2-wire: Data+/-, GND

Signals ISO

  • RS232: TxD, RxD, RTS, CTS, GND
  • RS422: Tx+/-, Rx+/-, GND
  • RS485 4-wire: Tx+/-, Rx+/-, GND
  • RS485 2-wire: Data+/-, GND
All signals isolated for 2.5kV

RS485 Data Direction Control

ARTc (Automatic Receive Transmit control)

Data Bits

7, 8

Stop Bits

1, 2


None, Even, Odd, Mark, Space

Flow Control



  • RS232: 180bps - 921.6/1000kbps
  • RS422: up to 12Mbps
  • RS485: up to 12Mbps


TxD/RxD for each port

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  Serial Port Expansion


USB 2.0 High Speed type A, 500mA @5V at rear side

Expansion Ports

connect USB-xCOM Plus to add more serial ports, also electrically isolated

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  • Windows 2000 to Windows 10 (x86 and x64)
  • Windows Server 2000 to 2016 (x86 and x64)
  • Linux (Kernel 3.4 and later built-in)
  • Mac OS X


The driver is already installed (Linux), or installs by automatic Download after Device connection (Windows).

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  Power Requirement

Input Voltage

  • 5V (USB)
  • 9-54V Dcin

Power consumption USB-8COM Plus

  • Bus powered: 5V 600mA via USB
  • Self powered: DCin 9 - 54V, 5W + 3W for Port Expansion

Power consumption USB-8COM Plus ISO

  • Bus powered: not available
  • Self powered: DCin 9 - 54V, 6W + 3W for Port Expansion

Port Expansion

DCin supply is compulsory to support Port Expansion.


  • Bus powered: USB Type B, no external supply
  • Self powered: 3-Pin Terminal Block

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  Housing and Mounting


0.8mm sheet metal


0.9kg, w/h box 1.5kg


196×147×44 mm³ (W×L×H)


310×192×60 mm³


  • 19-inch Rack
  • Wall mount

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  Environmental Data

Operating Temp

−25°C - 75°C

Storage Temp

−30°C – 85°C

Ambient Humidity

5-95% non condensing

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  Standards and Certifications




  • EN 55022 Class B
  • EN 61000-3-2: Limits of harmonic current emissions
  • EN 61000-3-3: Limitation of voltage changes
  • 47 CFR FCC Part 15 Subpart B

EMS (EN 55024)

  • EN 61000-4-3: Radiated RFI
  • EN 61000-4-4: Electrical Fast Transient
  • EN 61000-4-5: Surge
  • EN 61000-4-6: Induced RFI
  • EN 61000-4-8: Power Frequency Magnetic Field
  • EN 61000-4-11: Power supply dips


EN 61000-4-2 4kV contact 8kV air for

  • Serial Ports
  • USB
  • DCin Power connector

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  MTBF (Mean Time Between Failures)


28.1 Years @ 25°C
16.2 Years @ 45°C


18.7 Years @ 25°C
8.4 Years @ 45°C


Telcordia (Bellcore) Standard; RelCalc. 5.0 BELL-7

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Warranty Period

2 years

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  Ordering Information


USB-8COM Plus (8x RS232/422/485, non-isolated, expandable)


USB-8COM Plus ISO (8x RS232/422/485, isolated, expandable)

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Power adapter 110-230V AC to 12V @1A, DC, EU plug


Power adapter 110-230V AC to 12V @1A, DC, US plug


DB9F-to-TB/10 for RS422/485 free wiring option


DB9F-to-RJ45 for changing from DB9 to CAT5 wiring
(Optimised for RS422/485 operating modes)


RJ45-to-DB9M for changing back from CAT5 to DB9 wiring
(Required to match the DB9 pinout at USB-xCOM Plus)


Serial Null-Modem adapter 9PF-9PF, change male to female

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Packing list

  • USB-8COM Plus device
  • USB 2.0 High-Speed cable
  • Mounting brackets for 19-inch rack
  • Wallmount plates
  • Terminal block for Power Supply
  • 4 rubber feet for table mode

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 (v2.12.36.4 July 2021)
 (v2.08.30 July 2013)
 (Windows 2000 to 10)
 (Easy configuration and more)
 (Edition July 2017)
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* Specifications are subject to change without notice.
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