I'm using interface kit 1019 and the motion sensor 1111. I just tested the sensor. It is likely that when there's nothing move in the field, the analog output would be 2.5v. When something was moving in the field, the output voltage would change. The problem is that I can't find the rule about how it changed. Sometimes it went down and sometimes up. I thought it might be related to the distance between the moving object and the sensor and it might also be related to the moving direction of the object (from the center to the side in the field or otherwise).
Also, besides the rules of the value changing, is there any ways to quantify the motion? Like to detect the moving direction with the sensor.
Thank you greatly for the kind help!
Here's the link to the sensor: