The machine's COM port supports RS-232/422/485, but our RS-485 device is not detected. Where do we change the setting?

A multi-standard COM port runs one mode at a time, and the default is usually RS-232. Switch it to RS-485 in the place the vendor specifies. 1. Mode setting: depending on the model, this is in BIOS (Serial Port or Super IO configuration), via jumpers or DIP switches on the board, or through the vendor's utility. The model's manual states which. 2. Pinout: two-wire RS-485 uses Data+ and Data-, on different DB9 pins from RS-232. Check the pin table in the manual rather than copying another device. 3. Direction control: many ports offer automatic direction (auto flow) control. If software can transmit but not receive, check this option. 4. Communication settings: baud rate, data bits, parity, stop bits and device address must match at both ends. Note: some COM ports can supply 5 V or 12 V on pin 9. Enable it only when the device needs it; enabling it by mistake can damage the device.