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RESOLUTE™ FS absolute encoder system with RTLA30 linear scale

Features

  • Protocols: BiSS® Safety, DRIVE-CLiQ
  • Readhead size: 36 x 16.5 x 17.2 mm
  • Resolutions to 1 nm at 100 m/s
  • ±5 µm/m accuracy at 20 °C
  • Scale coefficient of thermal expansion at 20 °C:            10.1 ±0.2 µm/m/°C
  • Certified to:
    ISO 13849 Category 3 PLd
    IEC 61508 SIL2
    IEC 61800-5-2 SIL2

Benefits

  • Tape scale convenience and unrivalled ruggedness
  • Carrier-type scale system for quick, easy installation and replacement of scale
  • Excellent motion control performance
  • Exceptionally high dirt immunity
  • Wide set-up tolerances
  • Less than 10 nm RMS jitter for improved positional stability

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What is the RESOLUTE FS encoder?

The RESOLUTE FS (Functional Safety) series is a true-absolute, fine pitch optical encoder system that has excellent dirt immunity, and an impressive specification that breaks new ground in position feedback. It is the world's first absolute encoder capable of 1 nm resolution at up to 100 m/s. Ultra low SDE and jitter result in a rotary encoder system that outperforms any other encoder in its class. Certified to SIL2 and PLd for use in Functional Safety applications.

The Queen's Award for Enterprise: Innovation 2015

 

RESOLUTE true-absolute 30 µm encoder system, winner of the Queen's Award for Enterprise 2015 in the Innovation category

What is RTLA30 scale?

RTLA30 is a low profile stainless steel tape scale featuring 30  µm pitch absolute scale code. It is accurate to ±5 µm/m and available in lengths up to 21 metres. Two mounting options are available, both of which allow independent thermal expansion and tape scale convenience.

RTLA30 can be used with the revolutionary FASTRACK™ scale carrier system. This system allows a track to be laid quickly and easily with no need for fixing holes. A sacrificial spacer is removed and the tape scale is then fed into the track.

RTLA30-S is laid onto the substrate with self-adhesive backing tape. The self-adhesive is formulated in such a way that it allows for independent scale expansion to that of the substrate.

To complete the installation, both types of scale are clamped at one point to provide a datum position.

Why choose this encoder system?

Functional Safety certification

The RESOLUTE FS series is a true-absolute open optical encoder system with certification to the following Functional Safety standards:

ISO 13849 Category 3 PLd
IEC 61508 SIL2
IEC 61800-5-2 SIL2

Certain machinery safety functions, such as Safety Limited Speed (SLS), require the encoder feedback to be functionally safe. Utilising an encoder system that is already rated for use in these applications can make machine certification significantly easier. Adopting these advanced machine safety functions allows machine builders to make safer machines, capable of higher functionality that can reduce set-up times and machine downtime.

Excellent motion control performance

The RESOLUTE FS encoder's industry-leading performance is the result of a sophisticated, reliable and innovative method of operation. Crucially, the system uses a single track non-repeating “bar code” scale format with a nominal pitch of 30 µm. With its sophisticated optical design the RESOLUTE FS readhead captures a near-instantaneous image of this scale which, when analysed, allows a unique position to be identified at speeds of up to 100 m/s. The system allows position to be determined with resolution as small as 1 nanometre (1 billionth of a metre) and with low noise (jitter below 10 nm RMS) and SDE (Sub-Divisional Error, the error within a scale period) of just ±40 nm. This provides encoder feedback of superior fidelity, to ensure smoother velocity control and rock-solid positional stability.

Wide set-up tolerances

The RESOLUTE FS series does not follow the conventional technique of using dual tracks side-by-side (one incremental, one absolute) which inherently suffers de-phasing problems when small amounts of angular misalignment are introduced. Instead, this absolute encoder features a single track, optical absolute scale, combining both the absolute position and embedded phase information into one single code. This technology provides RESOLUTE FS encoders with far wider set-up tolerances (yaw tolerance ±0.5°) for quick and easy installation and superior long-term reliability, even if the motion axes settle or move over time. To further aid installation and diagnostics, there is an integral set-up LED on the readhead.

Interface option 

DRIVE-CLiQ interface

  • DRIVE-CLiQ interface for use with the RESOLUTE true-absolute optical encoderRequired for DRIVE-CLiQ protocol
  • Also available in dual head input for high accuracy rotary systems
  • Displays communication alarms
  • Duplicates readhead LED

Protocols

ProtocolDescriptionData sheet
BiSS SafetyRenishaw supports BiSS Safety (unidirectional) open protocol for absolute encoders. BiSS Safety is a high-speed serial protocol, perfect for dynamic axes that require high acceleration, smooth velocity control, excellent bi-directional repeatability and rock-solid positional stability.
RESOLUTE FS with BiSS Safety is available in both linear and rotary (angle) encoder versions.
RESOLUTE FS BiSS Safety

DRIVE-CLiQ

RESOLUTE FS with Siemens DRIVE-CLiQ serial interface is available for linear and rotary applications. DRIVE-CLiQ is the innovative, powerful communications interface to connect encoder and direct measurement systems with SINUMERIK and SINAMICS drive components.

RESOLUTE FS DRIVE-CLiQ

Technical specifications

Measuring standard

FASTRACK RTLA30: stainless steel tape scale with carrier system

RTLA30-S: stainless steel absolute coded tape scale with self-adhesive backing tape, for mounting directly to a substrate without the FASTRACK guide rails

Readhead size (LxWxH)

36 mm x 16.5 mm x 17.2 mm

Scale pitch

Nominal 30 μm

Thermal expansion coefficient at 20 °C

10.1 ±0.2 μm/m/°C

Accuracy grade at 20 °C

±5 μm/m

Scale length

BiSS Safety: up to 21 m for 1 nm resolution and up to 13.42 m for 50 nm resolution

DRIVE-CLiQ: up to 17.18 m for 1 nm resolution and up to 13.42 m for 50 nm resolution

Maximum speed

Up to 100 m/s

(See data sheet for details)

Protocols*

BiSS Safety, DRIVE-CLiQ†      

Resolutions

50 nm and 1 nm resolutions

Sub-Divisional Error (SDE)

±40 nm

Electrical connection

BiSS Safety: up to 10 m cable lengths, 9-way D and M12 connector

DRIVE-CLiQ interface: up to 9 m cable lengths and M12 connector

Power supply

5 V ±10%, max 250 mA @ 5 V (terminated)

Vibration (operating)

300 m/s2 max @ 55 Hz to 2 000

Shock (non-operating)

1 000 m/s2, 6 ms, ½ sine

Operating temperature

0 °C to +80 °C

Sealing

IP64

Refer to data sheets for full details.

For BiSS Safety and DRIVE-CLiQ specifications, refer to data sheets.

Downloads

Data sheets

Installation guide & safety manual

White papers

Technical drawings

How it works

The RESOLUTE FS encoder communicates bi-directionally in purely serial format, using a variety of industry-standard protocols, of both proprietary and open standard. 

RESOLUTE™ encoder optical scheme with annotations

The process begins

The controller initiates operation by sending a demand message to the readhead, instructing it to capture the absolute position on the linear or rotary scale at that instant. The head responds by flashing a high-power LED source to illuminate the scale. The flash duration is as brief as 100 ns to minimise image blur on moving axes. Crucially its timing is controlled within a few nanoseconds to preserve the relationship between demanded and reported position, one of the essential features that makes the RESOLUTE FS encoder ideally suited to very high specification motion systems. 

 

 

Single track scale

The scale is essentially a single track of full-width contrasting lines, based on a nominal period of 30 µm. The absence of multiple parallel tracks gives important immunity from yaw errors and much more lateral tolerance in head position.

Image acquisition

The scale is imaged, via an aspheric lens which minimises distortion, onto a custom detector array designed specifically for the RESOLUTE FS series. The optical arrangement, with a folded illumination path but direct imaging, is highly compact yet stable thus assuring the fidelity essential for excellent metrology.

Data decoding and analysis

Once captured by the detector, the image is transferred via an analogue-to-digital converter (ADC) to a powerful Digital Signal Processor (DSP). Specially developed algorithms then obtain a true absolute, but relatively coarse position from the code embedded in the scale. This process is checked, and corrections are made by further algorithms in the DSP which exploit redundancy and intentional restrictions in the scale code. Meanwhile other routines calculate a very high resolution fine position, which is then combined with the coarse position to provide a truly absolute and very high resolution location.

Final checks and data output

After final error checking procedures this information is uploaded in the appropriate protocol to the controller as a pure serial word representing position to within 1 nm. Protection against electrical noise disturbance is provided by addition of a Cyclic Redundancy Check (CRC). The entire process can take as little as a few micro seconds and be repeated up to 25 000 times per second. By a variety of techniques, including adjusting the light flash duration to the axis speed, this performance is achieved at up to 100 m/s while, crucially, preserving exceptionally low positional jitter at lower operating speeds.

And the result is...

An encoder with generous installation tolerances: the RESOLUTE FS encoder allows ±0.5° in yaw, pitch and roll and an impressive ±150 µm in rideheight. Meanwhile the generous optical footprint and advanced error correcting procedures confer excellent immunity to optical contamination, both particulate and greasy smears. All this while maintaining 1 nm resolution at 100 m/s: the RESOLUTE FS series is the answer to the toughest absolute challenge.