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TONiC™ incremental encoder system with RESM rotary (angle) ring


  • Readhead size: 35 x 13.5 x 10 mm
  • Resolutions to 1 nm
  • Speed to 3 673 rev/min
  • Ultra-low Sub-Divisional Error (SDE): typically <±30 nm
  • Vacuum compatible version available
  • Optical IN-TRAC™ reference mark


  • Low profile ring with large internal diameter for easy integration
  • Super-compact encoder readhead with dynamic signal conditioning for improved motion control
  • High dirt immunity
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What is TONiC?

TONiC is Renishaw's super-compact, non-contact encoder system that offers speeds up to 10 m/s and, when combined with the Ti interface, resolutions down to 1 nm for both linear and rotary applications. TONiC systems are quick and simple to install with wide set-up tolerances and calibration at the push of a button. TONiC's dynamic signal processing gives improved signal stability with ultra-low Sub-Divisional Error of typically <±30 nm to help realise superior motion control performance.

What is RESM ring?

RESM is a one-piece stainless steel ring with 20 µm pitch graduations marked directly on the periphery, featuring the IN-TRAC™ optical reference mark. Two versions are available in a wide range of sizes (Ø52 mm to Ø550 mm). ‘A' section rings, which offer an impressive installed accuracy and feature a taper mount system which reduces the need for highly toleranced machined parts and eliminates eccentricity. ‘B' section thin rings, which are low inertia and mass, are also available. Both 'A' and 'B' section rings 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 ?

Dirt immunity

High tolerance to dirt, scratches and greasy fingerprints and speeds of 10m/s mean that TONiC is ideal for more challenging applications. Furthermore, the non-contact RESM operates without friction or wear ensuring excellent reliability.

Ultimate reliability and performance in a compact size

For ultimate reliability, consistent performance and high dirt immunity, TONiC readheads incorporate third-generation filtering optics tuned for even lower noise (jitter) and now further enhanced by dynamic signal processing including Auto Gain Control and Auto Offset Control. This combination – all incorporated inside the readhead - provides signals of unrivalled purity and ultra-low Sub-Divisional Error of typically <±30 nm. The result is smoother velocity control for improved scanning performance and increased positional stability; essential parameters for so many applications, all in a compact readhead.

Quicker and easier installation

A set-up LED on the readhead gives a visual indication of signal size and an optional diagnostic kit allows remote checking of the system performance when the readhead is concealed within the machine. Calibration of the reference mark and incremental signals is done at the push of a button with no mechanical adjustment or additional diagnostic tools. The IN-TRAC customer-selectable optical reference mark is embedded in the incremental scale for compact dimensions and simplified alignment. This yields a reference mark output that is bi-directionally repeatable to unit of resolution over the full operating temperature and speed range.

Interface options

TD (dual resolution) interface

  • Selectable dual-resolutions quadrature output.
  • Ideal for applications that require high speed movement combined with finer precision motion.
Ti interface (square)

DOP (dual output) interface

  • Provides simultaneous digital quadrature and 1Vpp signals.
  • Designed for applications requiring one or more operations to be synchronised with a motion axis.TONiC Dual Output (DOP) interface

DSi (Dual Signal) interface

  • Renishaw's DSi combines the incremental signals from two TONiC readheads on a RESM ring (REST ring for partial rotation applications) to compensate for the effect of bearing wander and eliminates odd error harmonics, including eccentricity to give total l installed accuracy of typically ±2.0 arc second.TONiC Dual Signal interface with RESM rotary ring

Optional diagnostic kit

TONiC™ diagnostic kit (software and hardware)

TONiC diagnostic software version 1.0 (released March 2015) can be used to optimise the installation of TONiC encoders and provide a quick and comprehensive system calibration. The software must be used in conjunction with the TONiC diagnostic hardware which can be purchased from Renishaw using part number A-9411-0011. The hardware is connected to the PC via the USB cable (provided in the kit) or in-line with the customers' electronics.

Find out all about the TONIC diagnostic kit.

Technical specifications

Measuring standard

RESM: one-piece low profile stainless steel ring. Standard ‘A' section with tapered internal diameter or low inertia ‘B' section rings available

Also available for partial rotation applications as REST

Readhead size (LxHxW)

35 mm x 13.5 mm x 10 mm

Scale pitch

20 μm

Ring outer diameter

52 mm to 550 mm. For larger custom sizes, contact Renishaw

Line count

8 192 to 86 400 (depending on ring size)

Reference mark

RESM: single IN-TRAC reference mark ring

REST: two reference mark ring for partial rotation applications


Graduation accuracy

System accuracy

±3.97 to ±0.38 arc seconds (depending on ring diameter)

±4.28 to ±0.41 arc seconds (depending on ring diameter)

Maximum speed



(See data sheet for details)

3 673 rpm at -3 dB (on 52 mm RESM)

3 673 rpm (5 μm resolution TONiC on 52 mm RESM)

Sub-Divisional Error (SDE)

Typically <±30 nm

Dynamic signal control

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

Incremental signals



(See data sheet for details of angular resolutions)

1 Vpp (20 μm period)

Resolutions from 5 μm to 1 nm

Electrical connection

0.5 m, 1 m, 1.5 m, 3 m, 5 m and 10 m cable lengths with mini connector (connects direct to TONiC interface)

Power supply

5 V ±10%, <100 mA (analogue system), <200 mA (digital systems) (unterminated)

Vibration (operating)

100 m/s2 max @ 55 Hz to 2 000 Hz

Shock (non-operating)

1 000 m/s2, 6 ms, ½ sine

Operating temperature (system)

0 °C to +70 °C


Readhead: IP40

Interface: IP20

* System accuracy is graduation error plus SDE. Graduation accuracy is the maximum difference between the angle measured by a single readhead and the true rotation of the encoderas graduated. Application disturbances such as eccentricity are not included.

Refer to data sheets for full details.



Data sheets

Case studies

Technical drawings

How it works

TONiC 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 <±30 nm.

This evolution of filtering optics, combined with carefully-selected electronics, provide incremental signals with wide bandwidth achieving a maximum speed of 10 m/s with the lowest positional jitter (noise) of any encoder in its class. Interpolation is by CORDIC algorithm within the TONiC Ti interface, with fine resolution versions being further augmented by additional noise-reducing electronics to achieve jitter of just 0.5 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. Yielding a reference mark output that is bi-directionally repeatable to unit of resolution at all speeds. This unique arrangement also benefits from an automatic calibration routine that electronically phases the reference mark and optimises the dynamic signal conditioning