Features​

• Supports bidirectional communication between USB and a single RS485 channel, with hardware automatically controlling data transmit/receive direction
• Uses the FT232RNL USB-to-UART chip
• Isolated RS485 transceiver integrates signal isolation and isolated power supply
• USB side and RS485 side equipped with transient surge and ESD protection circuits
• Onboard self-recovery fuse, protection diodes, and 120 Ω termination resistor switch
• RJ45 interface provides 5 V auxiliary power output, maximum output current 100 mA
• Equipped with PWR, TXD, RXD indicators
• Supports Windows, macOS, Linux, Android, and WinCE

Product Specifications​

RJ45 Pinout​

The RJ45 interface uses the T568B wiring scheme. This interface is used for RS485 signals and power, and is not an Ethernet port.

The maximum output current for the 5 V auxiliary power on the RJ45 interface is 100 mA. Before connecting external devices, verify their operating voltage and current requirements.

Indicator Descriptions​

Isolation and Protection​

The product uses an RS485 transceiver that integrates signal isolation and an isolated power supply. The USB side and RS485 side are equipped with TVS, ESD protection devices, a self-recovery fuse, and protection diodes to suppress the effects of transient surges, electrostatic discharge, overcurrent, and overvoltage on the interfaces. Isolation and protection circuits do not replace on-site grounding, shielding, or lightning protection measures.

Product Dimensions​

Driver Installation​

The USB TO RS485 (D) uses the FT232RNL chip. After the operating system recognizes the device, it will be used as a virtual serial port. If the system does not generate a serial device, install the FTDI Virtual COM Port (VCP) driver for your operating system.

Windows Manual Installation​

1. Connect the converter to your computer. If the serial device in Device Manager shows a yellow exclamation mark, the driver is not properly installed.

   
   

2. Download the driver for your operating system from the FTDI VCP driver page. Run the Windows installer and extract the installation files as prompted.

   
   

3. Read the license agreement, accept the terms, and proceed with the installation.

   
   

4. After installation is complete, unplug and reconnect the converter. Confirm the COM port number under "Device Manager" > "Ports (COM & LPT)".

   
   

On Linux and macOS, confirm the device name in the system serial device list.

RJ45 Wiring​

The RJ45 interface on this product uses the T568B wiring scheme, but it carries RS485 signals and power, not Ethernet data.

Pins 4 and 5 provide 5 V auxiliary power output with a maximum output current of 100 mA.

Connecting to RS485 Devices​

Use an RJ45 adapter board or make a custom cable according to the peer device's pinout, and connect the following signals:

The 5 V auxiliary power on pins 4 and 5 should only be connected if the peer device's voltage and power requirements are confirmed to match, and the load current must not exceed 100 mA. If the peer does not require power, leave these two pins disconnected. Different devices may label RS485 A/B in reverse; if communication fails after correct wiring, refer to the peer device manual to verify polarity.

Termination Resistor Configuration​

The product includes an onboard 120 Ω termination resistor switch. RS485 buses typically enable termination matching only at both ends of the trunk line, while intermediate nodes keep it disabled. For short-distance, low-baud-rate communication, termination resistors are generally not required; for long-distance or high-speed communication where signal reflection occurs, enable them at both ends of the bus.

Bus start                         Intermediate node                         Bus end
[120 Ω: Enabled] ================= [120 Ω: Disabled] ================= [120 Ω: Enabled]

RS485 Communication Test​

1. Connect the target RS485 device according to RJ45 Wiring, verifying the A, B, and GND definitions.
2. Connect the converter to the host and confirm the virtual serial port in the system.
3. Open a serial debug tool, select the corresponding COM port, and set the baud rate, data bits, parity, and stop bits to match the target device.
4. Send test data and check the TXD, RXD indicators and the receive window.
5. If communication fails, check A/B polarity, serial parameters, termination resistors, reference ground, and cable connections in sequence.

Modbus RTU Device Communication​

USB TO RS485 (D) handles physical-layer conversion between USB and RS485 and does not include a built-in Modbus protocol stack. When connecting to Modbus RTU devices, the host software or master application must generate and parse Modbus frames.

1. Confirm the slave address, baud rate, parity, data bits, and stop bits.
2. Use a Modbus debugging tool or custom program to open the serial port corresponding to the converter.
3. Set the function code, register address, and data format according to the slave device protocol manual.
4. Send requests and check responses, indicators, and serial error messages.

Wiring Notes​

• RS485 buses should use twisted-pair cables; shielded twisted-pair cables are recommended for long-distance or high-interference environments.
• For multi-node communication, use a bus topology and avoid long star branches.
• Isolation circuits do not replace on-site grounding, shielding, or lightning protection designs.
• When routing cables near high-voltage lines, variable-frequency drives, or motors, maintain appropriate spacing, shielding, and grounding per site specifications.

Drivers and Chip Resources​

• FTDI VCP Drivers
• FT232 Driver - Windows 11
• FT232 Driver - Windows
• FT232RNL Product Information

Debug Tools​

• SSCOM Serial Debug Assistant
• SerialTool Android Serial Debug Assistant
• PuTTY Serial Tool

Support

Monday-Friday (9:30-6:30) Saturday (9:30-5:30)

Email: services01@spotpear.com