Absolute encoders

Encoders can be either absolute or incremental. Absolute encoders have a unique code for each shaft position. Or in other words, every position of an absolute encoder is distinctive. The absolute encoder interprets a system of coded tracks to create position information where no two positions are identical. Another feature is that absolute encoders do not lose position whenever power is switched off. Since each position is distinctive, the verification of true position is available as soon as power is switched on. It is not important to initialize the system by going back to a home base for a reference.

Absolute encoders can be either single-turn or multi-turn. Single-turn encoders are well suited to short travel motion control applications where position verification is needed within a single turn of the encoder shaft. Multi-turn encoders, on the other hand, are better for applications that involve complex or lengthy positioning requirements.

Absolute encoders have a number of advantages. First is the non-volatility of memory. An absolute encoder works as a non-volatile position verification device. True position is not lost if power is lost or the system moves while power is switched off. A continuous reading of position is not needed. This is specifically useful in those applications, such as satellite-tracking antennas, where position verification is key.

Absolute encoders also provide programming flexibility. By removing the need for system homing, the encoders can be controlled to give positioning programs based on setting up reference from point-to-point, rather than from a home position. Additionally, a microprocessor interface module allows for programming various operating parameters, such as resolution.

Safety is another benefit. In some applications where a loss of position could lead to operator injury or machine damage, an absolute encoder automatically provides position verification when the power is switched on.

Absolute encoders also have good immunity to electrical noise. The device determines position by frequently reading a coded signal. Stray pulses from electrical noise will not build up and accurate position is presented again on the next reading.

SICK introduces A3M Absolute Multiturn Encoder

SICK (www.sick.com) has unveiled a robust, absolute multiturn encoder that offers the new A3M encoder – a 14-bit sigleturn and 17-bit multiturn or a total of 31-bit output. Integrated with a Profibus output, the encoder features absolute encoders that are native to it, even without an internal power source.

Featuring internal electronics that are resistant to condensation and contamination, the new A3M is ideal for use in outdoor applications and harsh environment. Based on the design of magnetic technology that utilizes few moving parts, the new encoder’s advance versions can communicate through the DP V2, wherein Profibus can be directly used by motion control applications instead of a secondary motion control bus.

The new encoder’s conformal coating for resistance against a high IP rating and condensation makes it suitable for outdoor applications such as cranes and outdoor warehousing systems. The advanced models of the A3M60, which provides the DP V2 protocol, can be utilized in motion control applications where fast cycle times and speed are very important.

Aside from bag forming, palletizers, labeling, filling, sealing, and folding machines, the A3M60 can also be used in collision avoidance and position control applications. Other typical applications where the new encoder can be used include AGVs, assembly machine, welding and paint spraying robots.

The A3M60 is also suitable for the various needs of general manufacturing applications where a Profibus fieldbus network is utilized.

Renishaw Resolute absolute encoder offers sub-micron accuracy

Renishaw (www.renishaw.com) has announced the release of its latest Resolute absolute encoder which features Fanuc serial communication in linear encoder formats for grinding machines, high-precision machine tools and diamond-turning machines.

Resolute was designed to deliver sub-micron accuracy and resolution to one nm. A true absolute encoder, Resolute automatically determines absolute position upon switching on, effectively eliminating the need for reference returns or battery backup.

The new absolute encoder utilizes a detection method that is similar to an ultra-high-speed digital camera reading from a fine-pitch, non-repeating barcode scale.

Users can easily capture images, analyze and interpolate them to fine resolutions of up to one nm, even when operating at a maximum speed of 100 m/sec.

With immunity from contamination, this technique achieves broader setup and running tolerances attributed to the absolute encoder’s dirt-rejection and cross-checking capability.

Renishaw guarantees safety since the absolute encoder has been integrated with separate checking algorithm, which regularly monitors position and ensures problems are flagged up before reaching the controller.

To provide users with remarkably higher-fidelity encoder feedback, Resolute offers a harmonious mixture of scale technology and high-performance redhead.

With Sub-Divisional Error (SDE) controlled to within +/-40 nm, the dynamic response of the absolute encoder is optimized. As standard on RELA Invar scales, Resolute offers overall accuracy that is better than +/-1 um, while high accuracy at lengths up to five m is offered on RSLA stainless-steel scales.

RTLA-S and RTLA rugged steel tape scales, which offer +/-5 um/m accuracy, quicker and easier installation as well as lengths up to 10 m, are also available.

Rotalink’s low-cost absolute encoders with ovoid gearboxes

Rotalink (www.rotalink.com) has unveiled an innovative low-priced absolute encoder with ovoid style gearboxes. This compact encoder is directly fitted to the output shaft’s rear side to measure the load position and it is available for single-turn 360° rotation or multi-turn versions of up to 32,000 revolutions. The absolute encoder uses highly reliable and long-life non-contacting magnetic technology and provides a choice of a 10-bit per turn positional data or 0V-5V linear analogue output through a synchronous serial interface (SSI).

The device can be used to replace potentiometer-based angle encoders by combining position and motor feedback in one component or for low-cost servo feedback in rotary and linear actuators. Absolute position feedback is also very useful for machine homing. The device’s multi-turn option consists of an integral rechargeable battery, which maintains full position information for 20 hours if machine power is removed,

Rotalink designs and produces a variety of gearboxes in spur and planetary gearbox designs that feature polymer gears on ball or sintered bearings. The range also consists of ovoid-style gearheads, which include planetary gear assemblies for the output stages and a combination of spur gears for input stages. These are available in a choice of ultra-polymer materials.

The new absolute encoders are included in the company’s latest catalogue, which also features three new ranges of DC motor technologies – brushless, rare earth and heavy case – and new brushless version of the Red Drive motion controller and several gearbox lines.

EtherNet/IP Absolute Multi-turn Encoder from AMCI

Terryville, CT – Advanced Micro Controls Inc. (AMCI), has released the NR25 series of heavy-duty EtherNet/IP DuraCoder® encoders. These networked rotary sensors provide an overall measuring range of 16 bits (single-turn resolution) plus 14 bits (number of revolutions), or 30 bits total. With both single-turn and multi-turn versions available, AMCI’s EtherNet/IP encoders are ready for any application. Designed in accordance with ODVA guidelines, the AMCI NR25 EtherNet/IP encoders are 100% compatible with Rockwell Automation, Allen-Bradley, and Schneider PLCs that support EtherNet/IP.

NR25 EtherNet/IP DuraCoder Encoder Features:

• Up to 30 bit (65536 steps x 16384 revolutions) Resolution
• Absolute Single-turn and Multi-turn
• Power over EtherNet (PoE)
• Resolver-based Durability
• IP67 Ingress Protection Rating
• Solid Shaft and Hub Shaft Versions
• Stainless Steel Units Available
• ODVA Compliant

AMCI’s NR25 EtherNet/IP encoder comes standard with Power over Ethernet (PoE), making it possible to install this encoder using a single Ethernet cable that transmits data and power. The connector and cabling requirements are cut in half, plus installation is simpler and less expensive. Additionally, the ability to program with implicit and explicit messaging allows the NR25 series encoders to easily integrate with PLCs and PACs supporting EtherNet/IP. Position resolution, counting direction, velocity format, and presets are all configured easily through the EtherNet/IP port. And the ability to configure parameters simultaneously makes the NR25 encoder quick and easy to set up.

LEDs on the NR25 EtherNet/IP DuraCoders help technicians troubleshoot from the factory floor by displaying diagnostic information including module status, network status, and link/activity status.

The ODVA compliant NR25 EtherNet/IP encoders are offered in a 2.5” diameter package with two M12 connectors on the back, supplying power and EtherNet/IP connectivity. Using Power over Ethernet, users can save time and money while also simplifying wiring, as only one connector is needed for power and EtherNet/IP connectivity. The NR25 encoder is resolver based, meaning that it was designed to provide absolute position feedback without glass discs or sensitive LED components, enabling it to withstand high levels of shock and vibration. The IP67 rated package is the solution for single-turn and multi-turn position applications requiring protection from dust and water ingress. Stainless steel versions are also available for food grade and marine environments.

Advanced Micro Controls Inc.
www.amci.com

HBA4 Absolute Encoders from US Digital

US Digital announces the release of its latest absolute, blind hollow bore shaft encoder, the HBA4. HBA4 absolute encoders are used as azimuth and elevation position sensors in two axes tracking systems, commonly used in solar applications.

This single turn absolute encoder provides 16-bits of resolution over 360 degrees of shaft rotation. The HBA4 is available with a 12mm or 0.500” diameter bore size with either a ball bearing or sleeve bushing bearing assembly and is sealed to an IP66 rating.

The absolute encoder slips over a shaft and is locked in place with a non-marring clamp mount. A flexible anti-rotation tether provides single point mounting for bolt circles ranging from 2.50” up to 5.00” in diameter and compensates for shaft run out. The HBA4 communicates serially to a host via the industry standard RS485 bus.

US Digital
www.usdigital.com/hba4

Kübler by TURCK’s New Magnetic Single-turn Absolute Encoder Series

Minneapolis, MN — Kübler by TURCK introduces a new magnetic single-turn absolute encoder series specifically designed for extreme outdoor applications and heavy-duty construction machinery. The Sendix M3658 shaft and M3678 hollow shaft encoders incorporate patented Sensor Protect™ and Safety-Lockplus™ technologies to withstand harsh environmental conditions common in CANopen® and SAE J1939 applications.

Sensor Protect technology incorporates fully-encapsulated electronics and a separate mechanical bearing assembly, which provide an IP69K protection rating for both the encoder housing and flange. Due to this design, the Sendix M3658 and M3678 encoders can withstand the high-pressure water or steam cleaning that construction machinery requires without experiencing humidity or moisture ingress.

The encoders’ robust interlocking bearing design utilizes Safety-Lockplus technology that mechanically protects the shaft seal, allowing it to better tolerate installation errors and abrasion. A high resistance to shock and vibration enhances the encoders’ reliability, thus ensuring machines and motors run safely and dependably–without costly downtime due to repairs or unnecessary shutdowns.

The Sendix M3658 and M3678 encoders provide a resolution of up to 14 bits and a non-contact, wear-resistant measuring system. With the wide temperature range from -40 to 85° C and a high resistance to humidity, the encoders are well equipped to withstand outdoor applications that experience wide temperature fluctuations.

The new encoder series is equipped with a two-color LED located on the rear of the housing that indicates safe operation or fault status, as well as internal diagnostic status. A compact, 36 mm housing design allows the encoders to be easily installed in areas where space is limited.

TURCK
www.turck.us

TURCK Compact F36 Absolute Encoders

Minneapolis, MN — TURCK introduces the Kübler by TURCK F36 optical encoder series, designed completely without gears to eliminate wear and sensitivity to magnetic fields. F36 absolute encoders feature a compact size of only 36 mm with a hollow shaft diameter of up to 10 mm, making them well suited for drive engineering and medical applications.

F36 singleturn encoders have a resolution of up to 17 bits; multiturn encoders have a resolution of up to 41 bits with over 16 million revolutions. An IP 67 protection rating and a temperature range of -40 to 90°C ensure the encoders are able to withstand harsh environmental conditions.

Kübler by TURCK encoders employ state-of-the-art OptoASIC technology with high integration density that results in fewer components and connection points, increasing operational reliability. The encoders additionally offer a patented Safety Lock™ bearing structure, which enhances their ability to withstand vibration and eliminates installation errors.

TURCK
www.turck.us

Dual Encoder to USB Converter Module

BEI Industrial Encoders introduces the new Dual Encoder to USB Converter module. This module translates encoder position data to industry standard USB 2.0 format that can be accessed directly through a PC. Each module can handle signals from two SSI absolute encoders or two quadrature incremental encoders. An optional programmable data sample function allows users to automatically capture readings on a precise time clock.

Using a simple PC interface, this module can be programmed through the USB port for number of bits with absolute encoders. For incremental encoders, count mode (X1, X2, X4), reset, preset, and preset/reset on index are programmable through the USB. Incremental encoder counter register length is programmable, up to 32 bits. The Dual Encoder to USB Converter is ideal for system setup and debugging, data acquisition, analysis, monitoring and PC based control applications.

www.beiied.com