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.
Portfolio
Interface Modules
To integrate the WCS into higher-level systems via standardized interfaces, Pepperl+Fuchs offers a broad portfolio of interface modules. Up to four read heads can be connected to one interface module simultaneously. Choose the right version for your application from various interfaces.
Code Rails
Pepperl+Fuchs offers robust laminate code rails made of tear-resistant polyester laminate or stainless-steel code rails that are corrosion-resistant. Both variants are designed to be incredibly rugged and optimized for use under the most difficult of conditions. For maximum flexibility, the WCS code rails can also be mounted in horizontal and vertical curves using our code rail holders.
Mounting Systems
In addition to read heads, interface modules, and code rails, Pepperl+Fuchs offers various mounting systems. These include mounting bracket systems for the installation of code rails, aluminum profile systems for especially long distances, and a guide trolley that keeps the reader on track even in high-vibration applications.
Highlights of the WCS Positioning System
Precise Absolute Position Detection
The Pepperl+Fuchs WCS position encoding system has been on the market since 1989 and has been continuously developed and optimized through countless projects. It enables reliable position detection even with curved tracks, inclines, declines, interruptions, or switches.
Flexible Integration
The position value can be transmitted directly from the read head to the controller via a number of integrated interfaces, such as RS-485, SSI, CANopen, PROFINET, EtherCAT, or EthernetIP. A wide range of interface modules are available for connection to other fieldbus interfaces.
Rugged Design
Due to its U-shaped design, the WCS is resistant to ambient light and can even read dirty code rails with its powerful LEDs. Non-contact photoelectric scanning protects the WCS from wear and tear, and the Outdoor option offers protection up to IP69.
Simple Setup
The WCS Outdoor version features a translucent housing that offers good visibility of the indicator LED and display. This allows position information or error messages to be read quickly and easily.
WCS Read Heads
The U-shaped WCS read heads scan the stainless steel or laminate code rail photoelectrically and without contact. The read heads have internal light intensity control so they can reliably determine position values, even in difficult environmental conditions and despite contamination. RS-485, SSI, CANopen, IO-Link, PROFINET, EtherCAT, or EtherNet/IP interfaces can be used to transmit data to the controller. Different versions are available to users depending on the application. The WCS3 read head is the standard version, while a smaller version, the WCS2 read head, is also available.
The WCS read head with integrated IO-Link interface allows a quick, easy, and cost-effective way to integrate the device into IIoT applications. The system variant has identical dimensions to the previous devices. Existing code rails, mechanics, and accessories such as outdoor housings and carriages can continue to be used without restriction. In addition, predictive maintenance is ensured through comprehensive data sets: temperature, acceleration values in three axes, and a direction bit.
The WCS outdoor option is a read head with a protective housing for tough environments. Its rugged design with IP69 degree of protection resists dust, moisture, shocks, and vibration, suitable for areas with high-pressure cleaners or contact with saltwater, acids, and alkalis. The translucent housing lets maintenance easily view indicator LEDs and the optional display. Flexible connections support installations in tight spaces, with connectors for three installation positions.
For special installations, Pepperl+Fuchs offers the WCS read head with a display option. A seven-segment display is integrated into this read head. The display can be easily rotated by 180° so that the data is clearly visible directly on the read head when the installation is suspended or upright. System setup and troubleshooting have also been simplified. The display can show the current position value, diagnostic functions, and can draw attention to dirty or damaged code rail segments.
If an application requires an especially long distance, the special WCS Extended version makes it possible to cover a distance of up to 629 m. Assembly and integration of the two standard code rail segments are flexible. The extended read head can read the extended distance without additional programming.
For extreme temperatures, the WCS read head with heating option is an ideal solution. An integrated heating element permits an extended operating temperature range. Also available with the outdoor version, this enables the systems to be used in environments with temperatures as low as –40 °C. The combination of an integrated heating element, supplied via the read head, and a smooth housing surface makes this possible. Commissioning in both ice and snow is also feasible and it also protects against the risk of condensation due to rapid temperature changes from cold to warm.
The WCS2 read heads are the smaller than the standard WCS3 read heads. They are compatible with the WCS2 code rail and available with RS-485 or SSI interface. Due to their smaller design, they must be used with the aluminium profile system with guiding trolley. In addition to the standard version, there is a heating option available.
Interface Modules
Pepperl+Fuchs offers a wide range of interface modules for connecting WCS read heads to standard interfaces. All available interface modules are compatible with read heads with the special RS-485 interface, and up to four read heads can be connected. The following interface modules are available:
- PROFIBUS
- DeviceNet
- CANopen
- PROFINET
- EtherNet/IP
- EtherCAT
Code Rails
The WCS code rail is available in metal or plastic. Both variants are designed to be incredibly rugged and optimized for use under the most difficult of conditions. The rails can be laid not only on straight sections, but also on curved paths, ascents, and descents.
An ID pad is used to identify moving carriages: this short code rail segment is fastened to the mobile unit and detected by a statically mounted read head when it passes. This arrangement is also used for fine positioning. The ID pads for the WCS positioning system are available in stainless steel and laminate.
Mounting Systems
Pepperl+Fuchs offers a special solution for situations where the movement of the chassis causes major position fluctuations: A guide trolley decouples the read head from the vibrations of the vehicle and compensates for running tolerances between the vehicle and the WCS. The guide trolley is supported by the aluminum profile and the code rail, so that the read head is guaranteed to be in the optimal position at every point, even in the most challenging of conditions.
For straight layouts or navigating around horizontal/vertical curves, code rails can be easily mounted using a mounting bracket. Since the code rail is flexible, the mounting brackets and stabilization profiles can be used to easily create horizontal and vertical curves, lane changes, and circular movements.
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