Connect your display to the lift:
1) CANopen-Lift: use the plug and play abilities of the standard, all datas will be available to the display.
2) Old control panel or proprietary bus system: use an additional I/O module.
The I/O-module can be integrated directly at the signals' origin, for example, in the controler or in the terminal. For data connection to the display only 2 twisted wires are necessary.