LCD display screen open serial port failure is what reason?

Make sure my control card works. According to the control card applicable communication mode (RS232), LCD display to open the serial port failure is what reason? Thanks!

Your post has virtually zero information. There is no way to help you.

Read this sticky post: https://forum.arduino.cc/index.php?topic=97455.0

What Arduino?

What LCD? Post a link to a data sheet or where you got it.

Post your code. Read the how get the most out of this forum sticky to see how to properly post code. Remove useless white space and format the code with the IDE autoformat tool (crtl-t or Tools, Auto Format) before posting code in code tags.

If there are compile errors, please include the entire error message. It is easy to do. There is a button (lower right of the IDE window) called "copy error message". Copy the error and paste into a post in code tags. Paraphrasing the error message leaves out important information.

Post a schematic of your wiring. Show all components and power supplies.

Post photos of your wiring.