Arduino sends text messages.

To send data from the computer to Arduino, and then to the lower computer, you need to perform the following steps:

1. Install USB driver: If your Arduino board is connected to the computer through USB, you need to install the appropriate USB driver first so that the computer can recognize the Arduino board.

2. Writing Arduino program: Write a program in ArduinoIDE to receive data from the computer and send it to the lower computer. Serial library functions can be used to handle serial communication, such as Serial.begin (), Serial.available (), Serial.read () and Serial.write ().

3. Connect serial line: Connect Arduino board and lower computer through serial line. Generally speaking, you can use USB-to-TTL serial lines or other suitable serial lines for connection.