Hex or binary to arduino

Hi forum members, I have an issue with a very old item of plant, this plant out puts a digital signal in a series of connections 4 for one and 4 for another, 1101 and 1101 for example. I would like to capture the data into an arduino and display the data and if possible add more data to the message, my question is does anyone know if this has been done..

You need to know a bit more - how does it up date the data or write the data , how go you know when it is valid ? voltage levels , update rate etc ?

Hello
Do you have an interface specification?

The unit is connected to a step 5 seimens plc it seems it polls the varying binary each 2 seconds and displays all alarms and then goes back to the beginning.

My guess is the arduino would do the same, I don't beleive I need to log each alarm so it should only display what is being sent to it, sorry I have very few details, its circa 30 years old and the company who manufactured it longer exist.

At the moment it displays a 2 digit led number displaying 55 or 22 and we look it up on a key, the problem is one of the boards had failed and is no longer manufactured, I will probably end up fitting an annunciator, but I thought this would be a smaller cheaper fix.

Hello
It´s a parallel or serial interface?
What logical level voltage is used?