TONiC™ FS incremental encoder system with RESM20 rotary (angle) ring
Features
- Readhead size: 35 x 13.5 x 10 mm
- Speed up to 3 673 rev/min
- Detachable analogue (Ti) or dual output (DOP) interface*
- Certified to:
ISO 13849 Category 3 PLd
IEC 61508 SIL2
IEC 61800-5-2 SIL2
Benefits
- 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
- Ultra-low Sub-Divisional Error (SDE): typically <±30 nm
- Diagnostic kit

What is the TONiC FS encoder?
The TONiC FS series is Renishaw's super-compact, non-contact encoder system that offers speeds up to 10 m/s and, when combined with the DOP interface, resolutions down to 1 nm for both linear and rotary applications. TONiC FS systems are quick and simple to install with wide set-up tolerances and calibration at the push of a button. The TONiC FS encoder'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. Certified to SIL2 and PLd for use in functional safety applications.
* Only the analogue sine and cosine outputs are functionally safe.
What is RESM20 ring?
RESM20 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 ?
Functional Safety certification
The TONiC FS series is an incremental 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.
Ultimate reliability and performance in a compact size
For ultimate reliability, consistent performance and high dirt immunity, TONiC FS 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
Ti interface
- Analogue output, including a CAL button.
DOP (dual output) interface
- Provides simultaneous digital quadrature and 1 Vpp signals.
- Designed for applications requiring one or more operations to be synchronised with a motion axis.
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 | RESM20: 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 REST20 |
Readhead size (LxHxW) | 35 mm x 13.5 mm x 10 mm |
Scale pitch | 20 μm |
Coefficient of thermal expansion at 20 °C | 15.5 ±0.5 μm/m/°C |
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 | RESM20: single IN-TRAC reference mark ring REST20: two reference mark ring for partial rotation applications |
Accuracy* Graduation accuracy System accuracy | ±3.97 to ±0.38 arc seconds (depending on ring diameter) ±4.20 to ±0.40 arc seconds (depending on ring diameter) |
Maximum speed Analogue Digital (**use with DOP) | (See data sheet for details) 3 673 rpm at -3 dB (on 52 mm RESM20) 3 673 rpm (5 μm resolution TONiC on 52 mm RESM20) |
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 (**use with DOP) | (See data sheet for details of angular resolutions) 1 Vpp (20 μm period) Resolutions from 5 μm to 1 nm |
Electrical connection | 0.2 m, 0.5 m, 1 m, 1.5 m, 3 m, 5 m, 6 m and 10 m cable lengths with mini connector (connects direct to TONiC interface) |
Power supply | 5 V ±10% |
Vibration (system) | 100 m/s2, 55 Hz to 2 000 Hz, 3 axes |
Shock (system) | 500 m/s2, 6 ms, ½ sine, 3 axes |
Operating temperature (system) | 0 °C to +70 °C |
Sealing | Readhead: IP40 |
* 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 encoder as graduated. Application disturbances such as eccentricity are not included.
** Only the analogue sine and cosine outputs are functionally safe.
Refer to data sheets for full details.