Allen Bradley is a well-known manufacturer of sensors and safety products used in various industries, including automation, manufacturing, and food and beverage. One of their popular products is the photo eye, which is used for object detection in different applications. In this article, we will discuss the wiring diagram for Allen Bradley Photo Eye and provide some frequently asked questions about this product.
What is a Photo Eye?
A photo eye, also known as a photoelectric sensor or photo sensor, is an electronic device that detects the presence, absence, or position of an object using light. It works by emitting a beam of light and sensing the reflection or interruption of that light. Photo eyes come in different types and configurations, including diffuse, retro-reflective, and through-beam sensors.
Diffuse Photo Eye
A diffuse photo eye emits a light beam that reflects off an object and returns to the sensor. It detects the presence of an object by measuring the amount of light reflected back to the sensor. It is suitable for detecting objects at a short distance and in applications where the object to be detected is irregular in shape, size, or color.
Retro-Reflective Photo Eye
A retro-reflective photo eye emits a light beam that reflects off a reflector placed opposite to the sensor. It detects the presence of an object by measuring the amount of light reflected back to the sensor. It is suitable for detecting objects at a longer distance and in applications where the object to be detected is glossy or transparent.
Through-Beam Photo Eye
A through-beam photo eye consists of two separate units: a transmitter and a receiver. The transmitter emits a light beam that passes through an open space and is received by the receiver. It detects the presence of an object by measuring the interruption of the light beam between the transmitter and receiver. It is suitable for detecting objects at a longer distance and in applications where the objects to be detected are small or fast-moving.
Wiring Diagram for Allen Bradley Photo Eye
The wiring diagram for Allen Bradley Photo Eye depends on the type and configuration of the sensor. However, most photo eyes require a power supply and a switching device, such as a relay or a programmable logic controller (PLC), to control the output signal. Here is a general wiring diagram for a retro-reflective photo eye:
| Terminal Number | Description | Wire Color |
|---|---|---|
| 1 | Power Supply (+) | Brown |
| 2 | Power Supply (-) | Blue |
| 3 | Output Signal (NPN or PNP) | Black |
| 4 | Output Signal (+) | White |
Before wiring the photo eye, make sure to read the manufacturer’s instructions and specifications carefully. Also, ensure that the power supply voltage and current rating match the requirements of the sensor. Connect the wires according to their corresponding terminal numbers using wire connectors or crimping tools. Use a multimeter to verify the wiring and test the sensor’s functionality.
Frequently Asked Questions
How do I know if my Allen Bradley Photo Eye is working?
To test your Allen Bradley Photo Eye, connect the power supply and output signal wires according to their corresponding terminal numbers. Place an object in front of the sensor to verify that the output signal changes state. Use a multimeter or a scope to measure the output voltage or current and compare it with the sensor’s specifications. If the sensor does not detect the object or the output signal does not change, check the wiring, power supply, and switching device.
What is the difference between NPN and PNP output signal?
The NPN and PNP output signal refer to the type of transistor used in the sensor’s switching device. NPN stands for Negative-Positive-Negative, while PNP stands for Positive-Negative-Positive. NPN sensors have their load connected between the output terminal and the ground, while PNP sensors have their load connected between the output terminal and the supply voltage. The choice of NPN or PNP output signal depends on the type of input device used to control the load, such as a PLC or a relay.
Can I use Allen Bradley Photo Eye in hazardous environments?
Allen Bradley Photo Eye comes in different models and certifications that are suitable for hazardous environments, such as explosive atmospheres, dust, or moisture. These models comply with international standards, such as UL, CSA, and ATEX, and have special features, such as intrinsically safe barriers, explosion-proof enclosures, or IP ratings. However, make sure to check the specifications and ratings of the sensor before using it in a hazardous environment, and follow the appropriate installation and maintenance procedures.
How do I calibrate my Allen Bradley Photo Eye?
Calibrating Allen Bradley Photo Eye depends on the type and configuration of the sensor. Usually, the sensor has adjustment screws or potentiometers that allow you to adjust the sensitivity, the threshold, or the delay time. Refer to the manufacturer’s instructions and specifications for the correct calibration procedure, and use a test object that simulates the real object to be detected. Avoid using reflective or transparent materials for testing, as they may affect the sensor’s accuracy.
Can I use Allen Bradley Photo Eye with other brands of sensors and devices?
Allen Bradley Photo Eye has a standard output signal that is compatible with most types of input devices, such as PLCs, relays, or controllers. However, make sure to check the specifications of the input devices and use appropriate cables and connectors. Also, consider the compatibility of the communication protocols and the synchronization of the sensors if you intend to use them in a network or a system integration.
We hope this article has provided you with useful information about Allen Bradley Photo Eye Wiring Diagram. Remember to follow the safety precautions and the manufacturer’s instructions when using this product. For more technical support or troubleshooting, consult the manufacturer or a qualified engineer.
