UGREEN CR104 USB-A to RS232 DB9 Adapter with PL2303, 3m (20223)
USB-to-serial connectivity · SKU guide
UGREEN CR104 USB-A to RS232 DB9 Adapter with PL2303, 3m (20223)
SKU 20223 is a 3m USB-A male to DB9 male serial adapter built around a Prolific PL2303 USB-to-serial controller. It adds a virtual COM port to a compatible computer so software can communicate with true RS232 equipment that has a correctly wired DB9 female port.
Overview
This is a protocol-conversion cable, not a passive plug adapter. The USB side talks to the computer; the PL2303 converts that data to RS232 serial signalling; the DB9 male end mates with a compatible female equipment port. The application must then use the correct COM port, baud rate, data bits, parity, stop bits and flow-control settings.
The current SKU record and all eight gallery assets identify a Prolific PL2303 controller. The legacy page address contains older FTDI wording; that address text is not a chipset specification for SKU 20223.
Key features
These are the functions that define this SKU. They are intentionally separated from performance assumptions so the connector, protocol and operating role stay clear.
- USB-A male host plug for a computer with a standard USB Type-A port.
- DB9 male RS232 connector with thumb screws for a secure equipment-side connection.
- Prolific PL2303 controller presents a virtual serial COM device to the operating system.
- USB 2.0 host interface with listed serial transfer support up to 1Mbps under a compatible setup.
- Standard nine-signal DB9 assignment covers DCD, RXD, TXD, DTR, ground, DSR, RTS, CTS and RI.
- Cable shielding and moulded strain relief support dependable fixed-desk and service-kit use.
Performance and planning
This guide separates the physical connector, protocol, speed ceiling and host requirements so that a familiar-looking plug is not mistaken for guaranteed compatibility. Performance examples are planning references, not promises: the source device, destination device, controller, operating system, cable chain, file system and workload can all become the limiting factor.
The 3m length gives technicians working reach without changing the protocol. It does not increase the baud rate accepted by the connected equipment, and a longer physical run cannot correct electrical noise, poor grounding or an incorrect serial configuration.
The listed 1Mbps figure is a controller ceiling, not the setting to select automatically. Many routers, PLCs, modems, instruments and legacy peripherals use much lower rates such as 9600 or 115200 baud. Always follow the equipment manual.
Large file-copy benchmarks are irrelevant to RS232. Reliability is determined by correct framing, wiring, driver support, signal levels and the application maintaining the COM-port session.
Use scenarios
The following examples show realistic ways to use the product while retaining the compatibility and safety checks described elsewhere in this guide.
Industrial service
Connect maintenance software on a USB-A laptop to a compatible PLC, controller or instrument that exposes true RS232 through DB9 female.
Network equipment
Reach a supported router, managed switch or modem only when its console/service port is genuine DB9 RS232—not an RJ45 or USB console port.
Legacy peripherals
Operate compatible serial printers, scanners, GPS receivers, POS equipment or other DB9 RS232 devices after confirming their wiring and software requirements.
Lab and field kits
Keep the 3m cable with the correct PL2303 driver package and the target-device settings for repeatable commissioning or diagnostics.
Setup and usability guidance
Use this sequence as a practical installation checklist. If the connected equipment manual gives a stricter instruction, follow the equipment manufacturer’s procedure.
- Read the target equipment manual and confirm that its port is true RS232, DB9 female and compatible with a straight-through DB9 male adapter.
- Install a supported PL2303 driver if the operating system does not load one automatically; restart the application or computer if the driver installer requests it.
- Connect the USB-A plug directly to the computer where practical, then verify that a new COM or tty device appears in the operating system.
- With the equipment safely powered as its manufacturer directs, seat the DB9 male connector and tighten both thumb screws evenly by hand.
- Open the serial application and select the newly created port. Enter the equipment-specified baud rate, data bits, parity, stop bits and flow-control mode.
- Begin with a low-risk read or status command. If communication fails, stop and recheck pinout and settings rather than rapidly changing every value.
- Close the serial session before unplugging. Loosen the screws and pull by the connector shell, not by the cable.
Compatible devices and systems
Compatibility is conditional on physical connector, electrical or storage protocol, host support, software and the complete system design. A matching plug alone is not enough.
- Host: computer with USB-A and an operating system for which a suitable PL2303 driver is available.
- Systems represented in the gallery: Windows, macOS and Linux; edition, kernel and security-policy support still depend on the current driver.
- Equipment connector: DB9 female with true RS232 electrical signalling and compatible signal assignment.
- Typical categories include PLCs, network equipment, modems, printers, measurement devices and selected GPS/POS equipment only when their manuals specify RS232.
- Applications must support serial-port selection and the framing/flow-control parameters required by the equipment.
- Virtual machines, restricted corporate systems and USB hubs may require administrator approval or explicit USB-device pass-through.
What this product does
Use this product for the narrow functions below. Keeping the role specific makes troubleshooting easier and avoids buying it for an unrelated conversion task.
- Converts USB host data to RS232-level serial communication through the PL2303 controller.
- Creates a virtual serial device that compatible applications can open as a COM or tty port.
- Provides a DB9 male connection and hardware handshaking pins for equipment that uses them.
- Provides 3m of integrated cable reach between the USB computer and serial equipment.
- Draws operating power for the adapter electronics from the USB host connection.
What this product does not do
These exclusions are as important as the feature list. They distinguish this model from converters, powered accessories and visually similar products.
- It does not convert TTL-level UART, RS422 or RS485 signalling to RS232.
- It does not convert Ethernet, RJ45 console, parallel-printer or video signals.
- It does not guarantee that a DB9 connector has the required wiring; connector shape alone is insufficient.
- It does not automatically create a null-modem crossover. A separate correctly wired adapter may be required by DTE-to-DTE equipment.
- It does not supply operating power to the connected PLC, modem, printer or instrument.
- It does not remove the need for a compatible driver, serial application and correct port settings.
What to do
Good installation and handling habits protect data, equipment ports and connection reliability.
- Match SKU, PL2303 controller, USB-A host plug, DB9 male equipment plug and cable length before ordering.
- Download drivers only from the operating-system, controller or trusted product-support source appropriate to the host.
- Record the COM-port name and complete serial settings for each target device.
- Tighten both DB9 screws gently so vibration cannot loosen one side of the connector.
- Use strain relief and route the cable away from high-current switching equipment where possible.
- Test with the equipment manufacturer’s known-good command or utility before blaming the cable.
What not to do
Avoid these common mistakes even when the connectors appear to fit.
- Do not connect the DB9 end to TTL UART, RS422, RS485 or an unknown port simply because the connector fits.
- Do not assume “plug and play” means every operating system already contains the correct PL2303 driver.
- Do not select an arbitrary baud rate or disable flow control without checking the equipment documentation.
- Do not use an RJ45 adapter and assume a network console pinout will become compatible.
- Do not pull, twist or suspend equipment by the cable, and do not overtighten the DB9 screws.
- Do not disconnect while firmware, configuration or transactional data is actively being written.
Warnings and limitations
Review every point before connecting valuable equipment or irreplaceable data. Stop use if the setup does not match the documented interface.
- Incorrect serial voltage, wiring or handshake configuration can prevent communication and may damage sensitive equipment. Confirm the electrical standard first.
- The attached equipment needs its own appropriate power source; USB bus power operates the adapter electronics only.
- Driver availability can change with operating-system releases. Confirm support for the host version, architecture and security policy.
- A COM port appearing proves only that the USB adapter was detected. It does not prove that the remote equipment, pinout or application settings are correct.
- The listed up-to-1Mbps rate depends on compatible hardware and settings. Use the rate specified by the connected equipment.
- For SKU 20223, use the PL2303 identity shown by the current record and gallery; do not select an FTDI-only driver based on legacy address wording.
Technical specifications
The table consolidates the model facts and deliberately states conditional performance where the result depends on the wider system.
| Product | UGREEN CR104 USB-A to RS232 serial adapter |
|---|---|
| SKU | 20223 |
| Cable length | 3m |
| Host connector | USB Type-A male |
| Equipment connector | DB9 male with thumb screws |
| USB interface | USB 2.0 |
| Serial standard | True RS232 |
| Controller | Prolific PL2303 family |
| Listed serial rate | Up to 1Mbps in a compatible configuration |
| DB9 signals | 1 DCD; 2 RXD; 3 TXD; 4 DTR; 5 GND; 6 DSR; 7 RTS; 8 CTS; 9 RI |
| Driver model | Virtual COM/tty device; driver may be required |
| Operating-system scope | Windows, macOS and Linux with suitable PL2303 support |
| Adapter power | USB bus powered |
| Target-device power | Not supplied by this adapter |
| Signal conversion exclusions | Not TTL UART, RS422, RS485, Ethernet or parallel |
Package contents
Package contents below reflect the current product record and gallery presentation. Accessories shown only as connected examples are not automatically included.
- 1 × UGREEN 20223 3m USB-A to DB9 male RS232 adapter cable
- Printed material, packaging and driver-delivery method can vary; use the current trusted support source for software.
- A DB9 null-modem adapter, USB-C host adapter and power supply for serial equipment are not identified as included.
Check before ordering
A minute spent checking the complete signal path is more useful than choosing by connector shape or headline speed alone.
- You need the 3m length and SKU 20223.
- The computer has USB-A, or you have a proven data-capable host adapter.
- The target port is DB9 female and explicitly documented as true RS232.
- The target wiring is compatible with this straight-through DB9 male assignment, or you have the correct crossover accessory.
- A supported PL2303 driver is available for the operating-system version.
- You know the baud rate, data bits, parity, stop bits and flow-control requirements.
Care and troubleshooting
Start with the simplest known-good path, change one variable at a time and protect important data before testing storage or configuration workflows.
- Keep the DB9 contacts clean and dry, protect the USB plug in a service pouch and coil the cable loosely rather than sharply folding it.
- If the COM port disappears, reconnect directly to the host, inspect Device Manager/system logs and verify the driver before changing serial parameters.
- If the COM port remains visible but there is no response, check equipment power, DB9 gender, straight-through versus null-modem wiring, baud/framing and application access.
- If characters are corrupted, confirm that both ends use identical baud, data bits, parity and stop bits, then reduce the rate if the equipment manual permits.
- If hardware flow control is enabled, confirm that the target actually uses RTS/CTS or the required handshake lines.
Product-specific FAQ
Open a question to see the model answer. The FAQ is deliberately collapsible so detailed guidance remains easy to scan on a phone.
Does this cable create a serial COM port?
Yes. With a suitable PL2303 driver, the operating system exposes the adapter as a virtual COM or tty device that compatible serial software can open.
Is this an FTDI adapter?
No. this SKU 20223 record and gallery identify PL2303. Legacy wording in the page address should not be used to choose the driver.
Will it work with a USB-C-only laptop?
Not directly. The host plug is USB-A. A proven USB-C-to-USB-A data adapter or hub may work, but driver and USB-device pass-through must still be supported.
Can it connect to RS485 or RS422 equipment?
No. Those are different electrical standards. Use a converter specifically designed for the required RS422 or RS485 interface.
Can it connect to a TTL UART header?
No. TTL UART signal levels differ from RS232 and may be damaged by the wrong interface. Use a correctly rated TTL USB adapter.
Does it work with every DB9 female port?
No. The port must be true RS232 and must use compatible pinout, DTE/DCE orientation and handshake requirements.
Is a driver required?
Possibly. Some systems can load a suitable driver automatically, while others require installation. Confirm support for the host version and PL2303 controller.
Why is the COM port visible but the device does not respond?
Detection confirms only the USB side. Recheck equipment power, DB9 wiring, null-modem requirements, port ownership and all serial framing/flow-control settings.
Does the adapter power the serial device?
No. USB powers the conversion electronics. The connected modem, controller, printer or instrument needs its own specified power source.
Can I use it for an RJ45 network-console port?
No, not directly. RJ45 console wiring and connectors are different; choose an console cable documented for that equipment.
Is 1Mbps guaranteed?
No. It is the listed ceiling. The equipment and application usually dictate a lower baud rate, and the whole system must support the selected setting.
What should I check before disconnecting?
Close the serial session and confirm that no configuration, firmware or transaction is being written. Then loosen both screws and remove the connector by its shell.