For line sensor, my mentor (programming) said that Yellow means receiving no signal, and Orange means receiving signal is powerful.
And when we tried the line sensor, it showed Yellow and Orange at the same time… What does that mean?
Thanks 
anything not green means its on a line, idk what the orange means
Yellow means it sees the line. Orange means its receiving 2.5 times the signal required to activiate. Idieally, you want both yellow and orange. If you just have yellow, it will work.
What about green?
are they solid lights on the sensors?
we found that we had 2 sensors working perfectly and then went for the 3rd sensor and found out we had plugged it into the wrong port.
try checking your wiring to make sure you have it wired right, it should alternate between the 3 i believe…
Green means that the line sensors are getting less than the required signal required to activate.
wow that’s a lot… Actually we need 2 line sensors working, and we tried one of them and we plugged it into port 14, and others are not used.
And I’m sure I wired it right… It’s just I don’t understand what’s going on with color signs and the color that the sensor is detecting…
that means green is not detecting the line?
Green: no line detected
Yellow: line is detected
Orange: line detection is POWERFUL.
yeh. 
WHAT?! that’s not same as what my mentor said… how did you know it??
I’ve heard the same thing echoed around the forums, and it seems to be true for my testing. What did your mentor hear, and where did he hear it?
actually its she… but anyway
she said that green is detecting, yellow is not and orange is receiving powerful signal…
and i guess it was from internet because she was looking at her laptop…
According to the documentation (click here for documentation):
The orange LED is an alignment aid which indicates that a margin of 2.5 has been reached. This means that the sensor is receiving at least 2.5 times the signal strength back from the target needed to trigger an output signal. In general, it is desirable to have a higher margin to help overcome any deteriorating environmental conditions, i.e. dust buildup on the sensor’s lens. When aligning the sensor, the best performance can be obtained if this margin indicator is illuminated with the target in place.
All this info was in the paper instructions that came with the sensors in the bag. ::rtm:: I’d suggest checking that out, it might answer some questions you didn’t know you had.
FWIW, our experience is with the Allen-Bradley photoelectric sensors is:
Green = No IR reflected (e.g. pointed at carpet)
Yellow = IR reflected (e.g. pointed at gray tape)
Yellow + Orange = Very strong IR reflection (e.g. really reflective material)
We have the white wire of the sensor wired as the signal to a digital I/O on the digital sidecar.
Also, we needed to recalibrate the sensor (turning the sensitivity adjustment knob on the top) when we got the gray gaffer’s tape since we had been testing with much more reflective materials before that.