When wiring the crossing gates they need a signal for the gates to go down which is the normally open of the ITAD relay, they also need a signal for the gates to go up which is normally closed terminals of the ITAD relay. There is always power through the normally closed set of terminals and the micro switches on the crossing gates shut of power to the motors when the arms reach their stopping points. Now when you wire up one ITAD you have only one set of signals going to the crossing gates however when you add a second ITAD then you add a second set of signals. When one ITAD gets activated the relay clses and sends the signal for the normally open terminals on the relay to lower the gates. Now the second ITAD has not been activated so it is still sending the signal through the normally closed terminals on the ITAD relay for the gates to stay open so the lights will blink but the gates will not go down because they are getting conflicting signals. Putting a rectifier and a 12 volt relay on the normally open terminals of the ITAD and wiring the crossing gates through the contacts of the relay eliminates the opposing signals.
Matt,
So what would it look like with one crossing with two gates, two tracks, and two directions of travel?
