Welcome to the forum. When you create (or edit) a display, you can assign a unique number to each display. The PV can be configured to send the currently active display number to the PLC. This would allow the PLC to know which display is currently active on the PV screen. And of course, you can go the other way (as you are wanting to do). You can configure your PV to accept a number from the PLC and force that display to open on the PV terminal.