tao13:
i don't have a datasheet but i contacted the seller and he told me it is a digital pin and it works directly with arduino.
So i think it must write on serial 0 or 1 depends of the state of the optocuplor. Is it correct or not?
At least we now know what type of signal to deal with. Looking at the board there appears to be 2 visible LED's. One marked power that I suspect is always on when power is applied (I assume your powering the board from the arduino). The other marked sensor I assume lights when the IR sensor beam is blocked or vice-versa. Connect the boards 'out' pin to pin 8 of your arduino and try the below code. When you block/unblock the sensor the value scrolling thru the serial monitor should hopefully change and the sensor LED should also go on/off.
int sensorPin = 8;
int sensorValue = 0;
void setup() {
pinMode(sensorPin , INPUT_PULLUP);
Serial.begin(9600);
}
void loop() {
sensorValue = digitalRead(sensorPin);
Serial.println(sensorValue);
delay(100);
}