TONiC™ incremental encoder system with REXM20 rotary (angle) ring
Features
- Readhead size: 35 x 13.5 x 10 mm
- Resolutions to 1 nm
- Speed up to 3 673 rpm
- Analogue or digital outputs
- Ultra-low Sub-Divisional Error (SDE): typically < ±30 nm
- Vacuum compatible version available
- Optical IN-TRAC™ reference mark
Benefits
- Thick cross-section ring with installed accuracy of ± 1 arc second
- Super-compact encoder readhead with dynamic signal conditioning for improved motion control
- High dirt immunity
- Diagnostic kit to assist challenging installations and aid system optimisation

What is TONiC?
The TONiC™ series is a compact, non-contact incremental 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. Advanced filtering optics within the readhead give TONiC very low jitter, resulting in excellent positional stability and smoother velocity control. This makes TONiC the ideal encoder for applications where small movements must be tightly controlled.
The TONiC encoder features exceptional signal stability with low Sub-Divisional Error (SDE) of typically <±30 nm to help realise superior motion control performance.
TONiC also features an integrated setup LED for intuitive and efficient installation.
What is REXM20 ring?
REXM20 is a one-piece stainless steel ring with 20 µm pitch incremental graduations marked directly on the periphery, featuring the IN-TRAC™ optical reference mark. Its larger cross-section allows for the reduction in all installation errors apart from eccentricity, which is easily corrected using a DSi (Dual Signal Interface) and two readheads. Featuring 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?
Ultra-high installed accuracy
For the ultimate angular metrology, REXM20 with two TONiC readheads and a TONiC 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 TONiC readheads. Once the DSi has eliminated eccentricity, the only other errors remaining are graduation and SDE - both of which are minimal.
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.
Vacuum and Functional Safety variants
The TONiC encoder offers a single solution regardless of the application, with the same exceptional metrology capability offered by TONiCUHV, for Ultra-High Vacuum applications, and TONiC FS, for systems requiring Functional Safety certification to SiL2 and PLd.
Interface options
TD (dual resolution) interface
- Selectable dual-resolutions quadrature output.
- Ideal for applications that require high speed movement combined with finer precision motion.

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.
DSi (Dual Signal interface)
- Renishaw's DSi combines the incremental signals from two TONiC readheads on a REXM20 ring (REXT20 ring for partial rotation applications) to compensate for the effect of bearing wander and eliminate odd error harmonics, including eccentricity to give total installed accuracy of typically ±2.0 arc second.
Optional diagnostic kit

TONiC diagnostic software 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 | 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 °C | 15.5 ±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 | REXM: single IN-TRAC reference mark ring REXT: 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 Analogue Digital | (See data sheet for details) 3 673 rpm at -3 dB (on 52 mm REXM) 3 673 rpm (5 μm resolution TONiC on 52 mm REXM) |
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 Analogue Digital | (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 |
Sealing | Readhead: IP40 Interface: IP20 |
Refer to data sheets for details.