VBS用起来就是麻烦点，呵呵。WinCC帮助中是这样描述Screen对象的：
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Addressing with the picture name

'VBS8

Set objScreen = HMIRuntime.Screens("BaseScreenName.ScreenWindow:ScreenName")
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因此假设a为主画面,b为目标画面

Set objRectangle = HMIRuntime.Screens("a.PictureWindow1:b").ScreenItems("Rectangle1")