Click here to install the corresponding drivers.

Yes, it also supports Win7/8/8.1/10/11, Mac, Linux, Android, and WinC...

Remove the 120-ohm termination matching resistor for RS485.

• Support USB to RS232, RS485 or TTL;
• Does not support RS232, RS485, TTL simultaneous conversion to USB
• RS232, RS485 and TTL cannot be converted to each other

Not supported, RS232, RS485 and TTL can not be interchangeable, support USB to RS232, RS485, or TTL.

TTL and RS232 are full-duplex communication, you can short RXD and TXD to test, RS485 is half-duplex communication, you can test with an external USB to RS485 device, the following figure is the loopback test TTL:

VCC is the power supply pin, which can be switched by 5V or 3.3V (50mA) to power the connected device, if the device already has another external power supply, it can be connected without VCC.

• The module is only for interface switch in terms of hardware, it does not support Modbus. It supports connecting to Modbus devices with an onboard RS485 (RS232, TTL) interface.
• When learning the Modbus protocol, you need to understand Modbus's function code and data format. Modbus has a variety of function codes, each of which corresponds to one type of operation, such as reading the coil status, reading the input status, reading the holding register, and so on.

No, but it is more stable with a connection to GND. For better performance, reliability, and anti-interference, it is recommended to connecting to GND for a long-distance communication.

The isolation voltage is 5V.

This is a standard universal RS232 interface.
The RS-232 signal level is between +3V and +15V, or between -3V and -15V. Specifically, when the output voltage is between +5V and 15V, the driver outputs logic 0. When the voltage is between -5V and -15V, the driver's output logic is 1.