The connection method is as follows:

1. In EasyBuilder Pro software, select "All Topics", and in the "All Topics" content on the right side of the interface, click "Communication Port Footprint Definition" under "Hardware Settings".

2. In the "Communication Port Pin Definition" interface on the right, the touch screen models supported by EasyBuilder Pro software will be displayed. Click any model to display the DB9 pin definition for that model.

3. From step 2, it can be found that pins 5, 6 and 9 of touch screen DB9 are used for RS232 communication, and pins 1 and 2 are used for RS485 communication, and these pins are connected by shielded wires.

4. Open the EasyBuilder Pro software, create a new file, and then open the system parameters.

5. In the "System Parameters" interface, click "Add Device" and set external device parameters in the "Add Device" interface.

6. After setting, copy the written touch screen program to the touch screen, and the touch screen can communicate with two external devices by RS232 and 485 at the same time.