USB to RS232 4-Port FTDI Serial Adapter Cable - Adds Four DB9 Ports

Our review of the 4 Port Professional FTDI CHIP USB to RS232 Serial Cable looks at who needs extra legacy serial ports and why this adapter is a sensible, practical choice. For technicians, lab users, small POS operators and anyone who must attach multiple RS232 devices to a modern laptop, the key reason to buy is simple: it turns a single USB Type-A port into four stable DB9 serial ports using proven FTDI chipset compatibility and COM retention across reboots. Installation is straightforward on current Windows and macOS releases, and the cable requires no external power source.

Key Features

• Four serial ports: Adds up to four RS232 DB9 male ports from a single USB Type-A connection to support multiple legacy devices simultaneously.
• FTDI chipset: Uses a high-speed FTDI-based solution for broad driver support and reliable serial communication on Windows and macOS.
• No external power: The adapter is powered through the USB cable, so no separate power brick or cable is required during operation.
• COM retention: Maintains COM port assignments across reboots, reducing configuration headaches for repeat device connections.
• Wide device compatibility: Works with modems, GPS units, scanners, POS systems, routers and many serial console devices commonly used in labs and shops.

Who It's For

This product is aimed at IT professionals, field technicians, and small business owners who need to connect several RS232 devices to a modern laptop or desktop that lacks native serial ports. It is especially useful where multiple serial connections must be managed at once, such as configuring network equipment, running diagnostic tools, or operating legacy point-of-sale and lab instruments.

It is not suitable for devices that require legacy IRQ or I/O address support such as some serial mice, and users who need a ruggedized industrial-grade serial multiplexer or isolated ports should look elsewhere. Basic home users with a single serial device may prefer a single-port adapter instead.

Pros & Cons

Pros

• Provides four RS232 DB9 ports from one USB port, increasing connectivity without extra hardware.
• Good build quality and perceived value for money according to buyer feedback.
• Plug-and-play behavior with COM retention makes it convenient for recurring setups.
• Powered via USB so no external adapter is needed, simplifying use in the field.

Cons

• Some users report driver update issues and mixed labeling on ports, so initial setup may require manual driver checks.
• Does not support devices that require IRQ or I/O address assignment, limiting compatibility with certain legacy peripherals.

Specifications

Brand	TECHTOO
Connector	USB Type-A to 4 x DB9 male
Chipset	FTDI-based high-speed chipset
Ports	4 RS232 DB9 serial ports
Power	Powered via USB cable (no external adapter)
OS Compatibility	Windows 10 and macOS 10.x / 11.x (driver support required)
COM Retention	Maintains COM assignments across reboots

Our Verdict

The TECHTOO 4-port USB to RS232 adapter is a practical, cost-effective way to add multiple serial ports when working with legacy equipment. It offers reliable FTDI chipset compatibility, useful COM retention, and the convenience of USB-powered operation, making it a strong choice for technicians and small shops. Buyers should be prepared to check drivers and avoid devices that require IRQ/I-O level legacy support.

Frequently Asked Questions

Will this adapter work with Windows 10?
Yes. It is compatible with Windows 10; some systems may require driver updates from the FTDI vendor to ensure full functionality.

Does the cable need an external power supply?
No. The adapter is powered through the USB connection and does not require a separate power adapter.

Can it be used with serial devices that need IRQ or I/O address?
No. The adapter does not support devices that require IRQ or I/O address assignment, such as some older serial mice.