Table of Contents
Connecting a Proximity Sensor
Proximity sensors are widely used in industrial automation systems to detect the presence of objects without physical contact. They are commonly used for position detection, object counting, limit detection, and safety monitoring in machinery and production equipment.
FADUINO controllers support several types of proximity sensors commonly used in industrial environments. The following sections explain how to connect different sensor types to the controller inputs.
2-Wire Models
Two-wire proximity sensors are the simplest type of industrial sensor. They only require two connections: power and signal. Because the signal current flows through the same wires used for power, these sensors are often connected in series with the input circuit.
Two-wire sensors behave similarly to a switch. When the sensor detects a target object, the internal circuit changes state and allows current to flow. This current is detected by the controller input.
Key characteristics of 2-wire sensors:
- Only two wires are used for both power and signal
- Simple installation and wiring
- Commonly used in AC or DC powered systems
- Small leakage current may flow even when the sensor is OFF
When connecting a 2-wire sensor to FADUINO inputs, make sure the sensor's operating voltage matches the input specifications of the controller.
3-Wire PNP Models
Three-wire PNP proximity sensors are widely used in industrial control systems that use sourcing outputs. In a PNP sensor, the output provides positive voltage to the input when the sensor is activated.
A typical 3-wire PNP sensor has the following connections:
- Brown wire: Power supply (+V)
- Blue wire: Ground (0V)
- Black wire: Output signal
When the sensor detects a target, the output line (black wire) switches to the positive supply voltage. The controller input then detects this voltage as a logic HIGH signal.
Advantages of PNP sensors:
- Widely used in European and international industrial standards
- Reliable signal detection with low noise sensitivity
- Easy integration with sourcing input modules
3-Wire NPN Models
Three-wire NPN proximity sensors use a sinking output configuration. When the sensor detects a target object, the output transistor connects the signal line to ground (0V).
Typical wiring for an NPN sensor is:
- Brown wire: Power supply (+V)
- Blue wire: Ground (0V)
- Black wire: Output signal
When activated, the sensor pulls the output signal to ground. The controller input detects this condition as an active signal.
Characteristics of NPN sensors:
- Commonly used in Asian industrial equipment
- Compatible with sinking input circuits
- Suitable for applications requiring current-sinking outputs
When selecting between PNP and NPN sensors, ensure that the sensor type matches the input configuration of the controller.
