Thank you very much for your reply,By browsing other posts in this forum,
In your case you probably need to compile all your plc programs. You can use the command 'compile/all' (in edit mode), or set build/force In Options/Settings and build the node.
I have solved this problem by choosing force build in OPTION. When I was about to close the question, I didn't expect to see the answer. thank you very much.
Go ahead and fix some other issues, and come back for help if I really can't figure it out.
Drawing a gourd in the same way, it seems that the understanding is not so profound.It would be much faster if there were some introductory tutorials.
Writing the manual is a manual job (thanks to the author for his hard work), and so is reading the manual. The novice only has to take it step by step.