Pepperl+Fuchs Blog

Pairing Cable Pulls with Rotary Encoders

Posted by Ron Schlebusch on Fri, May 24, 2019

cable pull rotary encodersRotary encoders are industrial sensors that monitor acceleration, speed, and direction. They compile data on shaft rotation and convert it to an analog or digital output signal. A number of industrial communication protocols are available, including PROFIBUS, EtherNet/IP, and PROFINET. Rotary encoders are used in a wide range of industries, such as machine and plant engineering, material handling, and print/paper.

Cable pulls can be used with rotary encoders to provide high-resolution linear measurements. Common applications include conveyors, forklifts, gates, cranes, scissor lifts, drilling machines, shelving rack systems, and excavators. Cable pulls have a variety of benefits for these applications, and models like our ECN30 are designed to withstand extreme outdoor applications.

A cable pull / rotary encoder pairing can reliably monitor linear motion to measure distance and position up to 60 meters. The design of a cable pull rotary encoder, also known as a wire draw encoder, is simple: a spring-loaded measuring drum is wrapped by a single cable. When an application like an industrial crane pulls the cable in a straight line, it turns the measuring drum, and the encoder converts the number of drum revolutions into an output of your choosing.

Cable pulls can be paired with incremental or absolute rotary encoders. If an incremental encoder is used, the electrical measuring output is a voltage pulse stream. If an absolute encoder is used, the output is digital.

Cable pulls are most commonly paired with absolute rotary encoders, which provide position measurements as soon as they are powered on, even when position changes happened after the encoder was off. An absolute encoder can be a single-turn encoder to measure applications with no more than 360 degrees of rotation or a multi-turn encoder for applications that require measurements in both degree of rotation and number of rotations. Absolute rotary encoders use a variety of communication protocols, such as DeviceNet, EtherNet/IP, PROFIBUS, CANopen, and PROFINET.

Standard cable pull encoders contain mechanical parts. They must be kept lubricated and maintained to ensure long use. If the cable overstretches, it must be replaced to prevent measurement errors. If the temperature causes the lubrication to fail, this can cause reading errors.

To reduce the need for maintenance and to enhance linear movement detection performance, a cable pull can be paired with a magnetic rotary encoder. Magnetic rotary encoders use no mechanical gears in their sensing system, making them more durable. The encoder uses its internal magnetic sensors and a magnetic disk to detect movement and position of an application. These encoders can achieve measurement accuracies of 1° to 0.1° and are highly resistant to industrial elements.

Learn more about cable pulls and rotary encoders

Topics: Rotary Encoders, cable pulls

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