How to test whether the USB to serial data line communication is normal?

Step one: Plug the serial cable or USB-to-serial cable into the computer.

Second step: Open the serial port debugging assistant

Then select the serial port, serial port cable and

USB

to view the port number of the serial port to the serial port number. :

On the computer--right-click--Properties--Hardware--Device Manager-Port (COM

and LPT), click

Open the front of the port Just check the number.

Notes: 1. USB-SERIAL

CH340 (COM4) is the USB-to-serial port number

2. The communication port (COM1) is the original port number of the computer. With the port number

Step 3: Set up the serial port debugging assistant (see the picture below)

1. Serial port: COM4 is connected to the serial port cable or

USB converter The port number viewed by the serial port line in the above path.

2. Characters/data sent:

The input on the picture is 59, you can enter any 2 digits.

3. The remaining settings are as shown in the figure below.

Just use a short-circuit cap, iron wire, tweezers or the like to make a short circuit. If there is no electricity, it will be fine if you touch it with your hands.

4. Short-circuit pins 2 and 3 of the 9 pins on the serial cable or USB-to-serial cable (the pin bases are numbered, look carefully)

5. After the short-circuiting is completed , click with the left mouse button

Manual Send

on the Serial Port Debugging Assistant

You can see the following interface:

Conclusion: Every Click once to receive data once, indicating that the serial port and serial port line are normal.