How to collect the electronic labels of FTTB devices?

Choose Inventory > Project Document > Export Electronic Label from the main menu.

Or using CMD:

diagnose

(diagnose)%%display elabel ?
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  Command of diagnose Mode:

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emu                   Emu ELabel

frameid/slotid/subid<S><Length 1-15>

                      FrameID、SlotID、SubID

frameid/slotid<S><Length 3-15>

                      Board's FrameID and SlotID

frameid<U><0,1>       FrameID