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


  • 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


  • 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 encoder series integrates Renishaw's market-proven filtering optics and signal processing for superior metrology performance.

VIONiC encoders feature intelligent interpolation technology to give a digital output direct from the readhead. This provides ultra-low Sub-Divisional Error (SDE) and excellent dirt immunity, without the need for additional adaptors or separate interfaces. It also benefits from a compact footprint, without compromising on performance.

VIONiC readheads are compatible with a wide range of linear, partial arc and rotary scales.

Additionally, VIONiC encoders are designed with intuitive auto calibration mode and are easy to install. An optional Advanced Diagnostic Tool ADTi-100 is available for real‑time encoder data feedback during installation or for in-field diagnostics.

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?

Renishaw's highest performing incremental optical encoder

The VIONiC encoder series combines high-speed operation with fine resolution. The VIONiC readhead features an intelligent interpolation chip to give resolution as fine as 2.5 nm, offering high precision and repeatability in any application. The VIONiC encoder is available with a maximum clock rate of 50 MHz and operates at speeds up to 12 m/s. Speeds of up to 3.63 m/s are possible at a resolution of 0.1 μm, ideal for maximising throughput in the most demanding manufacturing processes.

Easy fault finding and servicing

The Advanced Diagnostic Tool ADTi-100 together with the ADT View software is available to provide comprehensive real-time encoder data feedback for more challenging installations and in-field diagnostics. This is especially helpful in applications when the encoder is hidden within a machine, enabling live diagnostics with minimal machine downtime. 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

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

0.2 m, 0.5 m, 1 m, 1.5 m, 2 m and 3 m cable lengths with D-type connectors (9 and 15 pin), circular in-line connector (12 pin) or 14-way JST connector

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



* < ±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.