FAQ
Q: Unable to use on non‑Windows systems. How to resolve?
A: Please go to the FTDI official website to download and install the driver for your operating system. After installation, reconnect the module or restart the system.
Q: Does it support Linux?
A: Yes. The module is compatible with Windows, Mac, Linux, Android, WinCE, etc. The actual detection depends on the system driver environment.
Q: What should I do if RS485 communication fails over short distances?
A: Try removing the 120Ω termination resistor, or lower the baud rate and test again. For short‑distance, low‑speed communication, termination is not always necessary.
Q: Does the module have a 120Ω termination resistor onboard?
A: Yes, it has a 120Ω balancing resistor. It can be used to reduce signal reflections in long‑distance or high‑speed communication. For short‑distance communication anomalies, adjust according to the field conditions.
Q: Does the USB TO RS485 (C) module itself support Modbus?
A: The module is a USB‑to‑RS485 physical layer converter; it does not have a built‑in Modbus protocol stack. It can connect to Modbus RTU devices, but Modbus function codes, register read/write, and data parsing must be implemented by the host software or main control program.
Q: Is it necessary to connect GND for RS485 communication?
A: For short distances and low‑interference environments, connecting only A+ and B‑ may work. For long‑distance communication, multi‑device communication, or strong interference, it is recommended to connect the RS485 side GND to obtain a more stable reference potential and better noise immunity.
Q: What is the purpose of the isolated design?
A: The isolated design reduces ground loops, common‑mode interference, and transient surges between the USB host side and the RS485 field side. It is more suitable for industrial environments, long‑distance communication, multi‑node buses, and high‑interference conditions.
Q: Why does the device disconnect automatically after working for a while?
A: First check the USB power supply, USB cable quality, driver installation status, and field interference. Try changing the USB port or computer, reinstall the FTDI driver, and inspect the RS485 bus wiring, grounding, and shielding.
Q: What if no COM port appears after driver installation?
A: Make sure you have installed the FTDI VCP driver. After installation, reconnect the module or restart the computer. If the problem persists, uninstall the abnormal device in Device Manager and then scan for hardware changes.
Q: Approximately how long does transmission/reception take?
A: The transmission/reception time depends on the baud rate, data length, system serial buffer, software polling method, and bus status. Please refer to actual test results.