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8 Port USB to RS-232/422/485 Octal Adapter

Name: 8 Port USB to RS-232/422/485 Octal Adapter
Brand: CoolGear
SKU: USB-8COMi-RM
Availability: Not in stock - Backorder allowed

Model No. USB-8COMi-RM

FTDI USB to Serial Adapter with Switching Power Supply

Industrial Grade Rack Mount 8 Port USB RS-232, RS-422, RS485 Octal Serial Adapter with Metal Case and Built-In 100-240Volt Power Supply utilizing a FTDI chipset.

Adds RS232, RS422, or RS485 Serial COM Ports to your system.
DIP Switch control with 8 sets of 4-pin DIP switches to control mode settings.
Utilizes a Built-in switching power supply of 100V-240V
Full RS-232 modem control signals and hardware/software flow control.

$439.99

Model No. USB-8COMi-RM

Expected Availability Date: March 16, 2026

Not in stock - Backorder allowed

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Product Documentation

Sofware & Drivers

FTDI Drivers

Quick Links:

Description

The USB-8COMi-RM 8 Port USB to RS-232/422/485 Serial Adapter is designed to make serial port expansion for industrial applications convienent and fast. Whether it’s connecting to a computer’s host USB port or USB hub, the 8 Port USB Serial Adapter instantly Adds eight RS-232, or RS-422, or RS-485 serial communication ports to your system using Plug-and-Play technology.

By connecting the 8 Port USB Serial Adapter to your computer, the adapter is automatically detected and installed with no IRQ & COM port conflicts or configuration since the ports do not require any additional IRQ, DMA, memory. The adapter is self-powered, and has built-in switching power supply of 100V/240V (input) inside the chassis.

USB Cable Connected to the FTDI USB to Serial 8 Port Adapter

The USB-8COMi-RM serial adapter is designed with 8 external 4-pin dip switches to independently set RS-232, RS-422or RS-485 mode conveniently, without the need to open the metal chassis. The adapter is with DIN rail bracket for industrial application environments and can be also mounted to a 19 rack, the rack mount kits are included with the adapter.

Termination and biasing option are available for data transmission lines. The USB-to-Octal RS-232/422/485 Adapter provides instant connectivity to RS-232, RS-422, RS-485 communication devices for POS, factory automation equipment, multi-drop data collection devices, bar code readers, time clocks, scales, data entry terminals, PC to PC long distance communications, ATMs and serial communication in harsh environments.

The USB-8COMi-RM USB to Industrial I/O provides industrial solution requiring single node or multi-drop communications over short and long distance.

USB-8COMi-RM Package Contents

Additional Features:

Adds eight RS-232, RS-422 or RS-485 serial ports by connecting to a USB port
No need to open chassis to set operation modes-eight external DIP switches for easy RS-232, RS-422, RS-485 mode settings
Installed as standard Windows COM port
SECC metal chassis with both DIN rail brackets and rack-mounting kits for flexible mounting
Full RS-232 modem control signals and hardware/software flow control
RS-232 data signals: TxD, RxD, RTS, CTS, DSR, DTR, DCD, RI, GND
RS-422 data signals: TxD-, TxD+, RxD+, RxD-, GND, RTS-, RTS+, CTS+, CTS-
RS-485 4-wire data signals: TxD-, TxD+, RxD+, RxD-
RS-485 2-wire data signals: Data-, Data+
Automatic transmit and receive control for 2-wire RS-485 half-duplex mode
Built-in termination and biasing
High speed serial port with the baud rate up to 921.6K bps
Non-standard baud rates supported
LEDs of Power, TxD and RxD for easy port monitoring and diagnostics
Serial port protected with surge protection of 10KV
Built-in switching power supply of 100V~240V
Easy plug and play installation and RS-232/RS-422/RS-485 device connection
COM port number assigned can be changed to any COM port number required
Works with USB 1.1 & 2.0 host port
Item Dimensions: 10.11(L) x 5.80(W) x 1.73in(H)

OS Support:

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

Package Contents

1x 8 Port USB to RS-232/422/485 Octal Serial Adapter
1x Mounting Brackets
1x DiN Rail Brackets
1x 3ft. USB-A to B Device Cable
1x Three Prong Power Cord
1x Driver Disk

*Surface Mounting screws not included.

Specifications

Product Specifications

Compliance

Country of Origin	Taiwan
Certifications	CE, FCC

Physical Characteristics

Color	Black
Mounting Style	Rack Mount
Ports	8 Serial Ports
Material of Construction	Galvanized Steel

Serial Attributes

RS Signals	Data-, Data+, GND, TxD-, TxD+, RxD+, RxD-, GND, TxD-, TxD+, RxD+, RxD-, GND, RTS-, RTS+, CTS+, CTS-, TxD, RxD, RTS, CTS, DSR, DTR, DCD, RI, GND
Serial Standards	RS232, RS422, RS485
Baud Rate	921.6K bps
FIFO Receive	384 bytes
FIFO Transmit	128 bytes
Data Bits	5, 6, 7, 8
Parity	None, Even, Odd, Mark, Space
Stop Bits	1, 1.5, 2
Flow Control	Hardware (RTS, CTS), XON/XOFF

Software

OS Support

Win XP, Win 7, Win 8, Win 10, Win 11, Linux, Mac OSX

Environmental

Operating Temperature	0C to 55C
Storage Temperature	-20 to 75°C (-4 to 167°F)
Humidity	5% ~ 95% (non-condensing)

Product Information

Warranty

1 year from date of purchase

Hardware

Chipset	FTDI
LED Indicators	Power, TX / RX
Upstream USB Ports	1 Type-B Female USB

Performance & Safety

Isolated/Surge Protected

Yes

Other Data

Connector	DB9 Male w/ Nuts
Chip Model	FT2232D, GL852, MAX3089E, ZT213LFEA
Warranty	1 year from date of purchase
Weight	4.5 lbs
Dimensions	16 × 8.5 × 2.5 in

UPC: 729440690984

Technical

Technical Specifications:

USB Bus
Compliance	USB 1.0/1.1 compliant, USB 2.0 compatible
Speed	12 Mbps, full-speed USB
FIFO	128 byte transmit FIFO 384 receive FIFO

Serial Interface
Port Type	RS-232/RS-422/RS-485 selectable
Number of Ports	8
Connectors	DB9 male

Serial Line Protection
ESD Protection	10KV

Serial Port Speed
Baudrate	300 bps to 921.6k bps

Serial Communication Parameters
Data Bits	5, 6, 7, 8
Stop Bits	1, 1.5, 2
Parity	None, Even, Odd, Space, Mark
Flow Control	RTS/CTS, XON/XOFF

Serial Signals
RS-232	TxD, RxD, RTS, CTS, DTR, DSR, DCD, GND, RI
RS-422	TxD-(A), TxD+(B), RxD+(B), RxD-(A), GND, RTS-(A), RTS+(B), CTS+(B), CTS-(A)
RS-485-4 wire	TxD-(A), TxD+(B), RxD+(B), RxD-(A), GND
RS-485-2 wire	Data-(A), Data+(B), GND

Driver Support
OS	Windows 7, Vista, 2003, XP (WHQL certified) and 2000 Linux Kernel 2.4 and up built-in support

Power Supply
Input	Self-powered Built-in AC to DC switching power supply with wide Range of AC input from 100VAC to 240VAC

Mechanical
Chassis	SECC metal chassis with DIN rail bracket Rack-mounting brackets included

Environmental
Operating Temperature	0 to 55 °C (32 to 131 °F)
Operating Humidity	5 to 95% RH
Storage Temperature	-20 to 75 °C (-4 to 167 °F)

RS-232 & RS-422 & RS-485 DB9 Male Connector Pin-outs

RS-232 - RS-422 - RS-485 DB9 Male Connector Pin-out Diagram

RS-232 DB9 Male

RS-232 Signal Pin-outs of DB-9 Male

	Pin	Signal
	1	DCD
	2	RxD
	3	TxD
	4	DTR
	5	GND
	6	DSR
	7	RTS
	8	CTS
	9	RI

RS-422 DB9 Male

RS-422 Signal Pin-outs of DB-9 Male

	Pin	Signal
	1	TxD- (A)
	2	TxD+(B)
	3	RxD+(B)
	4	RxD- (A)
	5	GND
	6	RTS- (A)
	7	RTS+(B)
	8	CTS+(B)
	9	CTS- (A)

RS-485 DB9 Male

RS-485 4-Wire (Full duplex) Signal Pin-outs of DB-9 Male

	Pin	Signal
	1	Tx- (A)
	2	Tx+(B)
	3	Rx+(B)
	4	Rx- (A)
	5	GND

RS-485 2-Wire (Half duplex) Signal Pin-outs of DB-9 Male

	Pin	Signal
	1	Data- (A)
	2	Data+(B)
	5	GND

RS-422 Signal Wiring

Point-to-Point 4 Wire Full Duplex

USB-8COMi-RM RS-422 Device

RS-422 with Handshaking

USB-8COMi-RM RS-422 Device

RS-485 Signal Wiring

Point-to-Point 4-Wire Full Duplex

USB-8COMi-RM RS-485 Device

Multidrop RS-485 2-Wire Half-duplex

USB-8COMi-RM RS-485 Device

Optional Accessories

The 8 Port USB to RS-232/422/485 Octal Adapter has certain accessories that work with it. These accessories are what you can order if needed.

Support

Product Documentation & Drivers

Product Documentation

Sofware & Drivers

FTDI Drivers

Need drawings, CAD files, or other compliance documentation? Click HERE

Serial F.A.Q.

Product F.A.Q.

View frequently asked product questions below. For all serial troubleshooting, visit this page.
Still need help? Reach out!

Do these adapters require an external power supply?
Most of our single and dual-port models are USB bus-powered. High-density rackmount models (8-port+) feature integrated or external power supplies for maximum signal integrity.
What is the difference between an isolated and non-isolated serial adapter?
Isolated adapters use optical barriers to physically separate the electrical signals. This protects your computer from 2,500V surges and ground loops common in factory environments.
Can I use these adapters with Windows 11?
Yes, all Coolgear Serial adapters use modern FTDI or Silabs chipsets with WHQL-certified drivers for full Windows 11, Mac, and Linux support.
What is COM Port Retention and why do I need it?
COM Port Retention ensures that your assigned COM port number remains the same every time you plug in the adapter or reboot your PC. This prevents software communication errors and eliminates the need to manually reconfigure your application settings whenever hardware is moved.
How do I clean and reinstall my FTDI drivers?
View Answer
1. Download the CDM Uninstaller HERE.
  
  Extract the zip file, or open the “CDMuninstallerGUI.exe” utility.
  
  Leave the ‘Vendor ID’ set to 0403 and ‘Product ID’ set to 6001.
  
  Click Add.
  
  Click Remove Devices.
  
  Download the corresponding driver for your operating system and follow on-screen prompts. Windows Driver | MacOS Driver
Video tutorial here.
How can I change my device’s COM port?
View Answer
1. Click on Start and navigate to the Control Panel
  
  Locate and click on Device Manager
  
  Under “Ports (COM & LPT)” you will find your serial device titled “USB Serial Port” along with its current COM Port.
  
  Right click on “USB Serial Port” and click on Properties.
  
  Navigate to the “Port Settings” tab and click on “Advanced…”
  
  Once there, the “COM Port Number:” can be changed with a dropdown menu to select the port number.
  
  Click your desired port number (i.e. COM2) and click “OK”.
  
  Click “OK” once more.
  
  Your serial device is now assigned to your chosen COM Port.
How do I check to ensure the COM port is listed properly in Windows?
View Answer
To ensure your serial device is installed properly, complete the following:
1. Press Windows Key + R to open the Device Manager. Once Run comes up, type “devmgmt.msc” into the text field and press Enter.
2. Expand the section labeled, Ports (COM & LPT).
3. You should now see a COM number in brackets to the right of each port. If the device is installed properly, no exclamation points or question marks should be present next to the device.
I have everything hooked up, but nothing is functioning correctly.
View Answer
To rule out potential issues, quickly test your individual components to ensure that they are working correctly individually, and are not the source of the problem:
- Serial cables
- Serial ports
- Serial devices
Test your components by:
- Hook up the serial cable(s), serial port(s), and serial device(s) in a different setup to see if the issue stems from a particular component, or the setup as a whole.
- Replace the serial cable, port, or device within your setup to further troubleshoot the issue’s origin.
When testing cables:
- Test each cable individually.
- Use short cables when you are testing.
When testing serial ports and devices:
- Press the Windows key + R, in Run, type devmgmt.msc, and press Enter to open the Device Manager. You can then check to see if your device is listed under Ports (COM & LPT).
- Ensure that the COM port number is the correct number for the serial device and that the software being used to connect the computer to the serial device uses the correct COM port number.
- If the device is listed with an error, follow the instructions on the website to reinstall the drivers.
Serial communication is not functioning correctly, how can I tell if the problem caused by the adapter or my serial software application?

View Answer
Older serial communication applications make use of legacy hardware addresses, often incompatible with PCI, PCIe, and USB to Serial products. Contact the software provider to troubleshoot.
I am receiving an error when I try to install the drivers in Windows 8 64 bit.
View Answer
Driver Signature Enforcement in Windows 8 may need to be disabled in order to use various drivers. After disabling this feature, the driver will be allowed to install.

Note: You are required to restart your computer after disabling the Driver Signature Enforcement. Save all open work on your computer.

Disable driver signature enforcement:
1. Press the Windows key + C.
2. Click Settings > Change PC Settings.
3. In the left pane, click General.
4. In the right pane, under Advanced startup, click Restart now.
When your system restarts:
1. Click Troubleshoot > Advanced options > Startup Settings > Restart.
2. Press 7.
When your computer restarts, Driver Signature Enforcement will be disabled and you can install the drivers.