I'm replacing the dead R2 main board with a Ramps 1.4/Mega 2560. I've modified it to handle 24v and keeping the R2 Hotend and heated bed. Everything moves and heats up at least on my test bench. I added a breakout board to get to the connections on the extruder cable. I want use the original IR sensor and have the ground and 5v/vcc figured out. But I need to know where to connect the ir sensor signal wire on to the Ramps board. Also what to set the Z_Min_Pin to in the Arduino code. Thanks for your help.