Overview
What are Sensors & Encoders?
Sensors and encoders are the primary feedback components in industrial automation, providing the "senses" needed for PLCs and motion controllers to operate. Sensors detect the presence, absence, or distance of objects without physical contact. They convert physical parameters—such as light, magnetism, or pressure—into electrical signals. Encoders are specialized transducers that translate mechanical motion into digital data, providing precise feedback on position, shaft angle, and velocity.
In a modern automated system, these devices work together to ensure safety, accuracy, and repeatability. For instance, a proximity sensor might detect that a part is in place, while a rotary encoder ensures the conveyor belt moves that part to the exact millimeter required for processing.
Main Manufacturers
PALM Parts Solution stocks high-performance sensing and feedback technology from leading global brands:
- Pepperl+Fuchs: Leaders in industrial sensors and explosion protection.
- Keyence: Specialized in high-end photoelectric, laser, and vision sensors.
- Omron: Providers of reliable proximity and fiber-optic sensing solutions.
- Allen-Bradley (Rockwell Automation): Integrated sensing for Logic-based systems.
- Siemens & ABB: Industrial-grade encoders and process instrumentation.
- Fanuc & Bosch Rexroth: High-precision motion feedback for CNC and servo systems.
- Delta Electronics & SEW-Eurodrive: Specialized encoders for motor and drive synchronization.
Typical Applications
Sensors and encoders are ubiquitous across all manufacturing sectors. Common applications include:
- Material Handling: Using photoelectric and ultrasonic sensors to track packages on conveyors.
- CNC Machining: Utilizing linear and rotary encoders for sub-micron positioning of cutting tools.
- Robotics: Integrating absolute encoders in robot joints for precise arm movement.
- Packaging: Employing color and mark sensors for high-speed labeling and sorting.
- Food & Beverage: Using IP69K-rated stainless steel sensors for washdown-heavy environments.
- Automotive Assembly: Leveraging inductive sensors for metal part detection and assembly verification.
Popular Product Families
We provide access to the industry’s most trusted product lines, including:
- Pepperl+Fuchs VariKont: Highly durable inductive proximity sensors for heavy industry.
- Allen-Bradley 871C & 42EF: Versatile proximity and RightSight photoelectric sensors.
- Keyence FS-N & PZ-G: High-performance fiber optic and photoelectric series.
- Omron E2E & E3Z: Globally recognized standards for proximity and small photoelectric sensors.
- Fanuc A860 Series: Specialized pulse coders and encoders for CNC spindle and motor feedback.
- Siemens SIMOTICS Feedback: Built-in encoders for SINAMICS drive systems.
- Sick (distributor equivalents): Including the popular deTec safety light curtains and AFM60 absolute encoders.
Replacement & Compatibility
When replacing sensors or encoders, matching the physical and electrical specifications is critical for maintaining system uptime.
- Sensor Replacement: Most inductive and capacitive sensors are interchangeable across brands (e.g., swapping an Omron E2E for an Allen-Bradley 871T) provided the diameter (M8, M12, M18, M30), mounting style (flush vs. non-flush), and electrical output (PNP vs. NPN) are identical.
- Encoder Migration: For encoders, compatibility is stricter. You must match the Pulses Per Revolution (PPR) for incremental models or the communication protocol (SSI, BiSS, Profibus) for absolute models.
- Legacy-to-Modern: many older encoders using 5V TTL logic can be upgraded to modern 10-30V Push-Pull outputs with the correct level converters, though direct replacements are always recommended to avoid rewiring.
- Standardization: Transitioning to IO-Link enabled sensors allows for cross-manufacturer compatibility and remote diagnostics, simplifying future replacements.
Selection Guide
Choosing the right sensing device requires evaluating the environment and the target object:
- Target Material: Use Inductive for ferrous metals, Capacitive for liquids/plastics, and Photoelectric for general object detection.
- Sensing Distance: Determine how far the object will be from the sensor. For long ranges (up to 100m+), use Laser or Ultrasonic sensors.
- Accuracy Requirements: For simple "Object Present" logic, a proximity sensor suffices. For tracking distance or position, a Linear Scale or Rotary Encoder is necessary.
- Environmental Factors: Will the sensor be exposed to oil, high temperatures, or high-pressure water? Check the IP rating (IP67 vs. IP69K) and housing material (Plastic vs. Stainless Steel).
- Output Logic: Ensure the sensor matches your PLC input card—PNP (Sourcing) for most Western systems or NPN (Sinking) for many Eastern systems.
- Mounting Constraints: Choose between cylindrical (threaded) or rectangular (block) housings based on the available space on the machine frame.
6 products · Delta Electronics
Frequently asked questions
What is the difference between a sensor and an encoder?
Sensors detect a presence or physical change (proximity, light, pressure) and provide an On/Off or analog signal. Encoders measure position, speed, and direction by converting mechanical motion into digital electrical signals. While a sensor tells you if something is there, an encoder tells you exactly where it is and how fast it is moving.
Should I use an incremental or absolute encoder?
Absolute encoders maintain their position data even when power is lost because each position has a unique binary code. Incremental encoders measure changes in position relative to a start point; if power is cut, they must return to a "home" position to recalibrate. Absolute encoders are preferred for critical safety or precision applications where downtime for homing is costly.
How do I choose between inductive and capacitive proximity sensors?
Inductive sensors detect metallic objects through electromagnetic fields and are highly durable in oily or wet environments. Capactive sensors detect both metallic and non-metallic objects (liquid, wood, plastic) by measuring changes in electrical capacitance. Use inductive for machine tools and metal parts, and capacitive for level sensing or non-metal packaging.
What are the three main types of photoelectric sensors?
Through-beam sensors use a separate sender and receiver, offering the longest sensing range and highest reliability in dirty environments. Retroreflective sensors use a single housing and a reflector, making them easier to wire but sensitive to shiny objects (unless polarized). Diffuse sensors bounce light directly off the target, requiring the least space but offering the shortest range.
What communication protocols do industrial sensors use?
Common communication protocols include IO-Link for smart sensors, SSI (Synchronous Serial Interface) for absolute encoders, and Ethernet-based protocols like EtherCAT, PROFINET, or EtherNet/IP for high-speed motion control. Many standard sensors still use simple NPN/PNP digital outputs or 4-20mA/0-10V analog signals for PLC integration.
What IP rating do I need for harsh industrial environments?
The IP (Ingress Protection) rating indicates resistance to solids and liquids. IP65 is dust-tight and protected against water jets. IP67 allows for temporary immersion in water. For food and beverage or high-pressure washdown environments, IP69K is required to withstand high-temperature, high-pressure cleaning.
Can I replace one brand of sensor with another?
Yes, most proximity and photoelectric sensors are cross-compatible if the mounting thread (e.g., M12, M18, M30), sensing distance, and output type (PNP vs. NPN) match. However, encoders often require specific shaft diameters, pulse counts (PPR), and electrical interfaces (Line Driver, Push-Pull, or Open Collector) that must match the drive or controller exactly.
What is the difference between NPN and PNP sensor outputs?
NPN (Sinking) sensors switch the negative side of the circuit, common in Asian-manufactured equipment (Keyence, Omron). PNP (Sourcing) sensors switch the positive side and are the standard in North American and European systems (Allen-Bradley, Siemens). You must match the sensor type to the input card of your PLC to avoid circuit failure.
When should I use a linear encoder instead of a rotary encoder?
A rotary encoder measures the movement of a rotating shaft. A linear encoder measures distance along a straight path using a scale and a read-head. Linear encoders are typically used in CNC machining and high-precision semiconductor assembly where leadscrew backlash could affect accuracy.
What are common causes of encoder failure?
Common causes include mechanical misalignment, excessive vibration, electrical noise (EMI) from VFDs, and moisture ingress. Using shielded cables, proper grounding, and flexible couplings for encoders can significantly extend the lifespan of these components in industrial settings.