I have two LED Call queuing displays. I don't know what is the english name for this but is LED display that you can increment one and people take paper ticket, used for counters, it looks something like this:
The two displays are connected with a RJ11/14 cable that sincronizes the information between them. I want to place a Arduino between them to get the current value in the display. I suspect the information between is passed using something like a serial connection (mostly because posts like this), however it may only send a tick event to the other board. I can't find a brand in the display, neither any documentation. What I would like to know is how should I try to reverse the RJ11 pinout.