Things to consider when selecting an industrial photoelectric sensor
bracket, and required cabling for power and connectivity? What are the environmental conditions in the area where the sensor(s) will be mounted? What level of ingress protection will the sensors need? 2. Beam Size. Select a sensor with a beam size that is appropriate for the size of the target you are looking to detect. The target must be big enough that it will break the beam and trigger detection. 3. Sensor Output. There are two- wire sensors and three-wire sensors. Each provide different outputs. In a two-wire sensor configuration, the sensor acts as a switch and will toggle the output on or off. With three-wire configurations, logic is required. In this case, the sensor triggers an event with a connected PLC using sourcing or sinking currents (PNP vs. NPN). 4. Output configuration. You will need to determine whether
In a diffused reflective sensor, the sensor again contains both transmitter and receiver in one unit, but instead of needing a reflector to return the beam to the receiver, the sensor is directed at an object and the light returns to the receiver. There are advantages and disadvantages to each sensor type. With Through Beam, longer range, reliability, and higher accuracy can be achieved. Areas such as wide door openings like a garage door or wide conveyors. This is due to light only needing to travel in one direction. There are some disadvantages as well. For example, cost is higher due to the need for multiple components, being able to detect through thin clear objects due to light refraction. With the need for two modules, set up can be more difficult as well. Things like mounting space requirements, cable management, and alignment prove to be a challenge depending on application. With retroreflective, cost is lower, and setup is easier having only one module and a reflector. There is no need for additional cabling and power, alignment is easier, but distance becomes shorter. Applications for retroreflective include baggage conveyors at airports, vehicle detection at toll gates, as well some material handling applications. Disadvantages of the retroreflective photoelectric sensor are at the
reflector. In situations where the object being detected is highly reflective, the sensor may fail to read the object. This can be avoided by adjusting the angles, but it is something to be aware of. With the beam being bi-directional, detection distance is also shorter. When looking at the diffuse photoelectric, cost is again lower, and there is only one point of installation. However, detection distance is much shorter. Rather than relying on a reflector to bounce back the beam, the sensor relies on objects passing in front of the beam. The other downside is depending on the material and color of the object being detected, the sensor may struggle in detection.
Considerations
When selecting your photoelectric sensor there are a number of things to consider before deciding on one type of photoelectric over another. Here are a few points you will need to look at. 1. Location. The location of the sensor plays a significant role in the type of sensor technology you can use. What is the detecting range for your application or to put it simply, how far with the object to be detected be from the sensor? Is there sufficient mounting space for the sensor module,
your sensor application would require a Light-on, Dark-on, Light-off, or Dark- off configuration is the next step. Depending on the needed configuration will help to select the proper sensor. Circuit function will help to identify the type of
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