Optical Linear Positioning (WCS)

In 1989, Pepperl+Fuchs introduced the WCS position encoding system—the world’s first optical positioning system—and has been continuously improving it ever since. Optical linear positioning systems are used for millimeter-precise detection of the position of shuttle cars and conveyor vehicles. The WCS absolute positioning system is based on the combination of a read head in a robust housing and a code rail made of stainless steel or laminate. This makes the WCS particularly suitable for use in demanding environments and for long distances. Because of its U-shaped design and its photoelectric scanning that protects against wear, it is resistant to ambient light. The outdoor version defies extreme ambient conditions due to the special housing of the WCS read head.

Smoke, dust, and temperature fluctuations have no impact—the WCS provides reliable positioning information, even at high speeds. The position value can even be reliably determined in challenging environments as it compensates for contamination by monitoring the received light intensity. The cutouts in the coding rail are practically impossible to get dirty. The absolute position encoding system detects a new position value every 0.8 mm over a large distance of more than 300 m and can transmit position values directly from the read head to the upper PLC. Due to a variety of integrated interfaces from RS485, SSI, IO-Link to EtherCAT, EtherNet/IP and PROFINET the connection to multiple PLC vendors is possible.

For safety applications, Pepperl+Fuchs combines the advantages of the proven WCS positioning system with a safe evaluation unit. The system consisting of the safe evaluation unit (Position Unit Safe, PUS) and two safeWCS/PUS read heads enables safe position and speed detection up to SIL 3 and PL e. The evaluation unit acts as a safe gateway to the fieldbus: It processes the redundant signals from the safeWCS/PUS read heads, creates a safe position value, and derives a safe speed value from it. In addition to the safe and non-safe data, it also transmits diagnostic data. The system supports the common safety protocol Fail Safe over EtherCAT® (FSoE) in order to transmit the acquired data from the sensor to a safe control system.

• Reliable and precise absolute position detection with the sophisticated position encoding system
• Precise position detection even on curved tracks, inclines, declines, lane changes, and gradients
• Flexible integration due to compatibility with all common control systems
• Reliable monitoring of safety-relevant applications through output of safe position and speed via Fail Safe over EtherCAT® (FSoE)
• IP69 protective housing for use in extreme outdoor applications in shipping ports and electroplating plants
• Simple setup and error indication: clearly visible LED status indicators and options with an integrated display