OK. Thank you for helping so far.
What would you suggest I use instead? I did some research and it seems an Arduino would be a good option. Can you recommend one for this task?
I'm confused about your comment that my logic is no good. You say it should never display a "corrupt" result. Since that is the only issue I am having and you seem to indicate it is a programming issue, why are you also saying speed is an issue? Your comment implies (even if you didn't mean it to) that if a programming error is fixed then my problem will go away.
I programmed with ladder logic. What I did is when someone rings in, it disables all the buzzers until reset by the "host" of the show. Also I made it so that pressing and even holding down the button only sends a quick pulse, rather than being able to hold closed a contact. The thing is that if two people ring in at exactly the same time it activates 2 relays at the same time and both send instructions to the outputs resulting in more than one set of lights lighting up. It activates 3 relays at the same time really. It activates lets say the relay that makes a 12 display and the the relay that makes a 14 display, as well as the one that disables all the buzzers. Since they all activate at the same time they all happen.
When I programmed this I assumed (incorrectly) that as soon as someone pressed a button it would disable the buttons, but instead what happens is that after a person presses a button there is actually a delay (milliseconds only I would guess) allowing another button to still activate it's relay.
So which is it? The programming is wrong? The Relay is too slow? Both? Could you elaborate on the answer you give please?
Thank you again.