PL2303 to RS485 Converter Adapter Support Win7 XP

Pinout & Connection Guide

RS485 Terminal Block

Important Wiring Rules for RS485

• Connection: Connect A to A and B to B across all devices on the bus. This is a straight-through connection, not a crossover .

• Ground: For distances over 100m or in electrically noisy environments, connect the GND terminals of all devices to provide a common reference voltage.

• Termination: To prevent signal reflections, place a 120Ω resistor between A and B at the two farthest ends of the cable .

• Cable Type: Use twisted-pair shielded cable (CAT5e or dedicated RS485 cable) for best noise immunity.

Wiring Examples

Connecting to a single RS485 device:

Converter Terminal      Device Terminal
    A       ───────────      A / D+
    B       ───────────      B / D-
    GND     ───────────      GND (if available)

Multi-drop network (daisy-chain):

• Connect A to A across all devices

• Connect B to B across all devices

• Connect GND in a star or daisy-chain configuration

• Place 120Ω termination resistors at the physical ends of the cable only

Usage Guide

Driver Installation

The PL2303 converter requires specific driver versions depending on the chip variant and operating system . Windows 10/11 often install drivers automatically, but manual installation may be needed.

⚠️ Important Compatibility Note: USB-Serial cables with PL2303 HX (non-HXD) chips are not supported on Windows 11 . The HXD and GC versions are required for Windows 10 and 11 compatibility .

Installation Steps (Windows 7/XP):

1. Download the correct driver: Based on your chip version and OS :

   • For HX chips on Win7/XP: Use PL23XX_Prolific_DriverInstaller_V260

   • For HXD/GC chips on Win7/8/10/11: Use PL23XX_Prolific_DriverInstaller_V400

2. Disconnect the device: Unplug the converter from USB before installation .

3. Run the installer: Execute the downloaded driver installer as Administrator.

4. Connect the device: Plug the converter into a USB port. The driver will install automatically.

5. Verify installation: Open Device Manager → Ports (COM & LPT). You should see “Prolific USB-to-Serial Comm Port (COMx)” .

Troubleshooting Driver Issues:

• If you see a yellow exclamation mark (Error Code 10), this indicates driver incompatibility, often due to counterfeit chips or improper driver versions .

• Solution: Uninstall the existing driver (check “Delete driver software”), then install the correct version from the table above .

• For Windows 11 with HXD chips, ensure you are using driver version V4.0.0 or later .

Changing COM Port Number

To change the assigned COM port (e.g., from COM10 to COM2 if your software only supports low port numbers):

1. Open Device Manager → Ports (COM & LPT)

2. Right-click “Prolific USB-to-Serial Comm Port” → Properties

3. Port Settings → Advanced

4. Select a new COM port number from the dropdown list

5. Restart your computer for the change to take effect

Testing the Converter

Once the driver is installed, you can test the converter using any serial terminal software (e.g., Putty, RealTerm, or Arduino Serial Monitor):

1. Loopback test: Connect the A and B terminals together using a short wire.

2. Open a serial terminal, select the converter’s COM port, and set the baud rate (e.g., 9600).

3. Type characters – they should be echoed back to the screen if the loopback is working .

Practical Communication Notes

• Baud Rate vs. Distance: Maximum transmission distance decreases as baud rate increases :

  • 0-10 meters: Up to 230 kbps

  • 300 meters: Up to 115 kbps

  • 1200 meters: Up to 57.6 kbps

  • 5000 meters: 9600 bps

• Anti-interference Performance: PL2303-based converters have been found to have poorer anti-interference performance compared to other chips like Silabs or CP2102 in industrial environments with significant noise .

• Grounding: In noisy environments, ensure a common ground is established between all devices on the RS485 bus to maintain signal integrity .