To undo the last executed operation, use one of the following methods:

1. Click the 'undo' button in the 'clipboard' area of the 'Edit' menu.

2. Press the Ctrl+Z shortcut key combination.

3. Right click on the program editor (ladder diagram/instruction list/function block diagram/function block), and then select the "undo" command from the context menu.

Multiple 'undo' commands can be issued to reverse keyboard operations. If "open", "close", "compile" or some conversion processing is performed on the ladder diagram as a whole, the "undo" buffer will be erased. The next operation record is the beginning of a new 'undo' sequence.