Just wanted to share. Been trying to come up with this for over a week now.
I have had a hard time trying to get this MTH signal (RailKing 1 over 1) with red green and black wiring to work properly using an IR sensor from Azatrax. It was either always red, or always orange or green. Now it is red when the sensor is broken, and orange for 10 seconds to green when the sensor pair can see eachother. Here is the wiring diagram I made. Every other one I could find didn't work quite the right way.
There are two jumpers. One ground from Q1 to P2 on the MRD1 and one hot from K1 to 1C on the MRAPR.
Hope this helps someone besides me!
Sensors are connected to the MRD1 in place of using an insulated track section.