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Rotary encoder

Firm grasp on angles and paths

Siko offers a rotary encoder that fulfills norm requirements, lessens environmental impact, and aims to make integration as efficient and simple as possible. Due to its robust design, it is suited for heavy-duty use in mobile machines.

With up to IP67, the rotary encoders can withstand extreme conditions (Photo: Siko)

Safety guidelines for mobile machines and their requirements have been a major component in constructing mobile machines, even before the introduction of EN ISO 13849. With the release of EN ISO 13849, many things have changed with regards to reliably recording angles and displacements. But new draft standards like EN 13000 for mobile cranes or EN 1175 for forklifts even go a step further, requiring additional measures. It’s not always possible to find a sensor that fulfills the standard while also meeting requirements for robustness and long service life. What’s more, these sensors might not be available with the necessary flexibility in terms of interfaces or connection technology.

Siko (Germany) has developed a redundant absolute rotary encoder, the VW58MR. It allows its customers to keep a firm grasp on angles and paths, even under extreme conditions. The rotary encoder has a category 2 construction, allowing it to be used up to SIL-2 and PL d.

The encoder is based on robust magnetic scanning technology. The measurement range of 4096 revolutions (12-bit multiturn) is broken into 16 384 steps (14-bit). A newly-developed gear allows the multiturn to capture information. In contrast to battery-powered or self-contained multiturn technologies, it continues to reliably deliver position values for years.

The two galvanically separated sensor units of the rotary encoder record positions entirely autonomously. Absolute position and speed are continuously provided to the controls through the interface. Customers can choose from three different versions of interfaces: In addition to a version with two separate CANopen interfaces (CiA 406), customers can also choose one with bus-in bus-out and two node IDs, and one which transmits via CANopen Safety.

A “hardcore” encoder

The encoder can handle extreme environmental conditions. Robust and resistant to environmental influences, it withstands the harshest weather conditions. With protection class IP65/IP67, a temperature range of -40 °C to + 85 °C, and a special coating process, it is suited for mobile machines with tough demands. A version is also available with a housing that is resistant to salt spray for use in harbor areas. Its strong double ball bearings mean high axial and radial loads on the shaft are no problem for this “hardcore” encoder.

The specialist for slewing ring positions

The encoder also has internal functions that make integration significantly easier for machine designers. Software was developed specifically to record slewing ring positions. Because the encoder is usually connected to the slewing ring via an external gear, which can also result in uneven gear ratios, conversion to a 0° to 360° value is not always easy for the machine manufacturer. This is because the position of the slewing ring should always be able to be resolved into 360°, no matter how often the slewing ring turns in one direction and even if the rotary encoder exceeds its internal zero point after 4096 revolutions.

Siko has implemented special software in the rotary encoder for this purpose. This software allows customers to configure the number of teeth for the slewing ring and the number of teeth for the external gear in the rotary encoder. This allows manufacturers to generate any gear ratio, which means the rotary encoder returns the exact position and speed of the slewing ring via the interface, relieving the machine manufacturer from having to recalculate the position.

Manufacturers can always use the same encoder system, no matter how big the slewing ring is. This allows the machine manufacturer to limit the number of versions.


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