FAQ
Q: Is the RJ45 connector on the USB TO RS485 (E) male or female?
A: The E model uses an RJ45 female socket, which accepts cables or adapters with RJ45 male connectors. The interface follows T568B pinout but does not carry Ethernet data.
Q: Can I connect the RJ45 interface to a switch or router?
A: No. The RJ45 is used only as a connector; it carries RS485 signals, along with a 5 V auxiliary power output and GND pins. It is not an Ethernet interface.
Q: Can I use a standard T568B network cable to connect devices?
A: A standard straight-through cable maintains a one-to-one pin correspondence, but you must still verify that the RJ45 pinout on the peer device matches this product. If the pinout differs, use an adapter board or a custom cable.
Q: How do I confirm the RJ45 pinout?
A: Pin 1 = A (A+), Pin 2 = B (B-), Pin 3 = NC, Pin 4 = 5 V, Pin 5 = 5 V, Pin 6 = NC, Pin 7 = GND, Pin 8 = GND. When using the 5 V auxiliary power, the load current must not exceed 100 mA. If the peer device does not use the power pins, leave pins 4 and 5 disconnected.
Q: I installed the driver but still do not see the serial port. What should I do?
A: Verify that the FTDI VCP driver for your operating system is installed, then unplug and reconnect the converter. On Windows, you can uninstall the malfunctioning device in Device Manager and scan for hardware changes. If it still is not recognized, try a different USB port or host computer.
Q: Can I use this on Linux systems?
A: Yes. It is compatible with Windows, macOS, Linux, and Android. The actual device name and driver loading behavior depend on the operating system.
Q: Can I use Modbus RTU with this product?
A: The product performs only USB-to-RS485 physical-layer conversion and does not include a built-in Modbus protocol stack. Modbus function codes, register read/write operations, and data parsing must be implemented by the host software or master application.
Q: I've wired it up but communication fails. How should I troubleshoot?
A: First, verify the RJ45 plug-to-socket pin numbering, the peer device's pinout, A/B polarity, and serial port parameters. Then check the reference ground, cables, and termination resistors. Note that different manufacturers may label A and B oppositely — always refer to the target device's manual.
Q: How do I use the onboard 120 Ω termination resistor?
A: On the E model, the 120 Ω termination resistor is fixed in circuit and cannot be disabled via switch. Termination resistors should typically be placed only at the two ends of an RS485 main line. Therefore, place this converter at a bus endpoint; do not use it as a middle node.