Hi Jacques,
Well, I'm no electrical engineer or programmer, but I would imagine at the very least and electrical engineer would need be employed, and one certified in the area of material lifts. Depending on what feature(s) you wish to add, you would have to provide original electrical drawings specific to your existing lift. Overlays as we call them are pretty much a thing of the past. Taking an existing older system or just a basic lift that travels two or three floors with no indicators or other desirable features and wanting to "upgrade" to enhance or add certain features/operations is expensive. But if you've got the money, I'm sure there is someone who can/could do it, as long as there is no infringement on local codes/regulations regarding alterations to the original design certificate . The better bet or investment is to have a package deal from a lift mfg'r that shows the user exactly what he wants to see or use in your case. To take your "goods hoist" and have it display or function like a modern type OEM freight/material lift is asking a lot in my opinion. But it's just that...my opinion.

Hi elmcannic.

Thanks for the reply.

Basically what I've got going as far as getting this system to work. My plan is to send (use limits etc) +24V to a signal converter of sorts (hoping I can find a signal converter suiting my requirements).
The said signal converter then has to take the 3X +24V signals and 1X common and convert/switch this to a signal that the display can understand.

Not sure if there is a device like this available on the market but hoping you guys can give me more insight?

Check out CE electronics website. They have several options that use descrete inputs. This way s one example.

http://www.ceelectronics.com/elevator-accessories/110-msl05-xxxx

The problem is that I already have a display unit.
Need to make the unit work on the signals I have available (24Vdc) I know majority of micro-controllers only work on max 5Vdc for inputs so I was thinking of using resistors to lower the voltage.

Seems like a major headache for basic UI. A lot of unknown variables here... Not saying it can't be done but trying to communicate with hardware/software or even the most basic circuitry and produce readable human information sounds painstakingly time consuming. Best of luck.

Could you give us some more info on the display unit you have and the equipment you are trying to make it work on?

But if you just need to convert a 24vdc input to 5vdc you should be able to use a simple voltage divider circuit.

The Display unit I am using is a Chinese unit thus I have had no luck finding anything on the unit. It is a SM.04VL16/G.

I have been thinking of using arduino to try make the unit work but I dont even know how to connect up the display, so dead-end there.

the signal I am sending is a voltage that will be activated by limit switches on the elevator.