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VIONiC™ incremental encoder system with REXM20 rotary (angle) ring

Features

  • Digital output direct from the readhead
  • Readhead size: 35 x 13.5 x 10 mm
  • Resolutions to 2.5 nm*
  • Speed up to 4 400 rpm
  • Ultra-low Sub-Divisional Error (SDE): typically <±15 nm* (see technical specifications)
  • Optical IN‑TRAC™ reference mark

Benefits

  • No separate interface required
  • Advanced Diagnostic Tool for easy fault finding, challenging installations and servicing
  • Thick cross-section ring with installed accuracy of ± 1 arc second
  • High dirt immunity
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What is VIONiC?

The VIONiC readhead combines Renishaw's market proven filtering optics and advanced interpolation into one digital incremental encoder with ultra-high accuracy.
The VIONiC encoder system offers a wide variety of speed and resolution configurations, and an expansive range of linear or rotary scale options. This makes it one of the most versatile encoder for high precision feedback. Designed with intuitive auto-calibration mode, VIONiC readheads are also easy to install.

What is new?

*The VIONiC encoder system is now available in resolutions down to 2.5 nm with enhanced SDE across the product range.

What is REXM20 ring?

REXM20 is a one-piece stainless steel ring with 20 µm pitch incremental graduations marked directly onto the periphery, featuring the IN-TRAC™ optical reference marks. Its larger cross-section allows for the reduction of all installation errors apart from eccentricity, which is easily corrected using a DSi (Dual Signal Interface) and two readheads. It features total installed accuracy up to ±1 arc second, zero coupling losses, and exceptional repeatability.
REXM20 is available in a range of sizes (Ø52 mm to Ø417 mm) and line counts, all of which have a large internal diameter for flexible integration. The non-contact format eliminates backlash, shaft wind-up (torsion) and other mechanical hysteresis errors that are inherent in traditional enclosed encoders.

Why choose this encoder system?

All purpose digital encoder system

VIONiC is the encoder of choice because it combines high speed interpolation with impressive metrology performance making it suitable for even the most demanding applications. A wide range of encoder configurations are available so that the user can optimise the speed and resolution of their system depending on their motion control requirements. Furthermore the VIONiC readhead works with both linear and rotary scales accross a range of accuracies. The VIONiC encoder is quick and easy to calibrate, meaning it is suitable for volume production.

Easy fault finding and servicing

The Advanced Diagnostic Tool is available for comprehensive encoder feedback . This can be used for challenging installlations and fault finding. It provides:

  • Remote calibration functions
  • Signal optimisation over axis length
  • Readhead pitch indication
  • Limit and reference mark indicators
  • DRO and lissajous outputs.

Ultra-high installed accuracy

For the ultimate angular metrology, REXM20 with two VIONiC readheads and a VIONiC DSi (Dual Signal interface) offers exceptional repeatability, zero coupling losses and better than ±1 arc second total installed accuracy. The REXM20 features a thicker cross-section designed to minimise all installation errors except eccentricity, which is easily corrected using the combined output of two VIONiC readheads. Once the DSi has eliminated eccentricity, the only other errors remaining are graduation and Sub-Divisional Error - both of which are minimal.

DSi (Dual Signal interface)

VIONiC™ DSi Dual Signal interface

Renishaw's DSi combines the incremental signals from two VIONiC readheads on a REXM20 ring (REXT20 ring for partial rotation applications) to compensate for the effect of bearing wander and eliminates odd error harmonics, including eccentricity, to give total installed accuracy of typically ±2.0 arc seconds.


Optional Advanced Diagnostic Tool ADTi-100

Advanced Diagnostic Tool ADTi-100

The VIONiC encoder system is compatible with the Advanced Diagnostic Tool ADTi-100 and ADT View software. They provide comprehensive real-time encoder data feedback to aid more challenging installations and diagnostics. The intuitive software interface can be used for:

  • Remote calibration
  • Signal optimisation over the entire axis length
  • Readhead pitch indication
  • Limit and reference mark indication
  • Digital readout of encoder position (relative to the scale)
  • Monitoring the velocity against time graph
  • Exporting and saving data

Technical specifications

Measuring standard

REXM20: one-piece ultra-high accuracy stainless steel ring

Also available for partial rotation applications as REXT20

Readhead size (LxHxW)

35 mm x 13.5mm x 10mm

Scale pitch

20 μm

Coefficient of thermal expansion at 20 °C15.5 ±0.5 μm/m/°C

Ring outer diameter

52 mm to 417 mm

Line count

8 192 to 65 536 (depending on ring size)

Reference mark

REXM20: single IN-TRAC reference mark ring

REXT20: two reference mark ring for partial rotation applications

Total installed accuracy (with 2 readheads)

(≥100 mm diameter) ±1 arc second

(75 mm diameter) ±1.5 arc seconds

(≤57 mm diameter) ±2 arc seconds

Maximum speed

4 400 rpm (for 52 mm diameter ring)

(See data sheet for details)

Sub-Divisional Error (SDE)

Ring diameters ≤135 mm, typically <±20 nm

Ring diameters >135 mm, typically <±15 nm*

Dynamic signal control

Real time signal conditioning including Auto Gain Control (AGC), Auto Balance Control (ABC) and Auto Offset Control (AOC) for optimised performance during operation

Incremental signals


5 μm to 2.5 nm resolution

(See data sheet for details of angular resolutions)

Electrical connection

0.5 m, 1 m, 1.5 m, 2 m and 3 m cable lengths with D-type connectors (9 and 15 pin) or circular in-line connector (12 pin)

Power supply

5 V -5%/+10%, typically <200 mA fully terminated

Vibration (operating)

100 m/s2 max at 55 Hz to 2 000 Hz

Shock (non-operating)

500 m/s2, 11 ms, ½ sine, 3 axes

Operating temperature (system)

0 °C to +70 °C

Sealing

IP40

* <±10 nm SDE can be achieved with optimised set-up. Please contact your local Renishaw representative for more details.

Refer to data sheets for full details.

Downloads

Data sheets

White paper

  • White paper:  The accuracy of angle encoders White paper: The accuracy of angle encoders

Technical drawings

How it works

The VIONiC encoder features the third generation of Renishaw's unique filtering optics that average the contributions from many scale periods and effectively filter out non-periodic features such as dirt. The nominally square-wave scale pattern is also filtered to leave a pure sinusoidal fringe field at the detector. Here, a multiple finger structure is employed, fine enough to produce photocurrents in the form of four symmetrically phased signals. These are combined to remove DC components and produce sine and cosine signal outputs with high spectral purity and low offset while maintaining bandwidth to beyond 500 kHz.

Fully integrated advanced dynamic signal conditioning, Auto Gain , Auto Balance and Auto Offset Controls combine to ensure ultra-low Sub-Divisional Error (SDE) of typically <±15 nm.

This evolution of filtering optics, combined with carefully-selected electronics, provide incremental signals with wide bandwidth achieving a maximum speed of 12 m/s with the lowest positional jitter (noise) of any encoder in its class. Interpolation is within the readhead, with fine resolution versions being further augmented by additional noise-reducing electronics to achieve jitter of just 1.6 nm RMS.

TONiC™ optical scheme with annotations

The IN-TRAC™ reference mark is fully-integrated in the incremental scale and is detected by a split photodetector within the readhead. As the diagram shows, the reference mark split detector is embedded directly into the centre of the incremental channel linear photodiode array ensuring greater immunity from yaw-dephasing. This unique arrangement also benefits from an automatic calibration routine that electronically phases the reference mark and optimises the incremental signals.