Angle Encoders
with Integral Bearing

08/2022

Table of contents

Overview

4Angle encoders from HEIDENHAIN
Selection guide

Absolute angle encoders
with integral bearing and hollow shaft

6

Incremental angle encoders
with integral bearing and hollow shaft

10

Absolute and incremental angle encoders
with integral bearing for a separate shaft coupling

12

Measuring standard, measuring method andphotoelectric scanning

14

Technical features and mounting information
Measuring principles
Angle encoders with integral bearing andintegrated stator couplingSpecifications

Angle encoders with integral bearing fora separate shaft coupling

Technical Information Regarding:• Accuracy of Feed Axes
• Safety-related position measuringsystems• EnDat 2.2: bidirectional interface forposition encoders• Encoders for feed axes with direct drives

18

Angle encoders for direct drive motors in machine tools

20

Mechanical design types and mounting

22

Benefits of the RCN 2001, RCN 5001 and RCN 8001

24Functional safety

28

Mounting and accessories

30

General information

36

Series or model

System accuracy

RCN 2001 series±4”/±2”38

RCN 5001 series±4”/±2”42

RCN 8001 series±2”/±1”¬ 60 mm

46¬ 100 mm50

Electrical connection

For more information, visit
www.heidenhain.com, or contact us.
Brochures:• Modular Angle Encoders• Linear Encoders for NumericallyControlled Machine Tools• Exposed Linear Encoders• Rotary Encoders• Encoders for Machine Tool Inspection
and Acceptance Testing• Interfaces of HEIDENHAIN Encoders

Measuring accuracy

Diagnostics, and inspection and testing devices

This brochure supersedes all previous
editions, which thereby become invalid.
The basis for ordering from HEIDENHAIN
is always the brochure edition valid when
the order is placed.
Standards (ISO, EN, etc.) apply only
where explicitly stated in the brochure.

Further information:
For detailed descriptions of all available
interfaces, as well as general electricalinformation, please refer to the Interfacesof HEIDENHAIN Encoders brochure(ID 1078628-xx).

54

Angle encoders from HEIDENHAIN

The term “angle encoder” usually refers to
encoders with an accuracy better than ±5”
and a line count of more than 10 000.

Angle encoders with an integrated
bearing, for a separate shaft coupling
ROC and ROD solid-shaft angle encoders
are ideal for applications with high shaft
speeds or applications requiring wider
mounting tolerances. Via the couplings,
axial tolerances of up to ±1 mm can berealized for the shaft-side coupling.

Rotary table

Angle encoders are found in applications
requiring precision angular measurement
at accuracies within several arc seconds.
Examples:• Rotary tables on machine tools• Tilting axes on machining centers• C axes on lathes• Measurement and inspection equipment• Printing units of printing machines• Telescopesetc.

For a selection guide, see Page 12/13

ROC 7380 absolute angle encoder

In contrast, rotary encoders are used inapplications where accuracy requirements
are less stringent (e.g., in automation,
motors and many other applications).
RCN 8511
8000

Mounted angle encoder (e.g., RCN 8511 on the rotary table of a machine tool)

Angle encoders differ in the following
mechanical design principles:
Angle encoders with an integral bearing,hollow shaft and stator coupling
The structural design of the stator coupling
has the effect that the stator coupling must
absorb only the torque resulting from thebearing friction, particularly during angularacceleration of the shaft. These angle
encoders therefore provide excellent
dynamic performance. Thanks to the stator
coupling, the system accuracy includes theerror of the shaft coupling.

Angle encoders without integral bearing
The optical angle encoders without an
integral bearing (modular angular
encoders), such as the ECA and ERA, aredesigned for integration into machineelements or measuring equipment. They
meet the following requirements:• Wide hollow-shaft diameters (up to 10 mwith a scale tape)• High shaft speeds of up to 20 000 rpm• No additional starting torque caused byrotary shaft seals• Segment versions

The RCN, RON and RPN angle encoders
feature an integrated stator coupling,whereas the stator coupling of the ECN isexternally mounted.
Other benefits:• Compact size for limited installation
space• Hollow shaft diameters of up to 180 mm,
providing space for power cabling, etc.
• Easy installation• Versions with functional safety
Selection guide• For absolute angle encoders, readstarting on Page 6• For incremental angle encodes, readstarting on Page 10/11

4

ECA 4410 absolute angle encoder

Thanks to their robust design, the ECM
and ERM magnetic modular encoders areespecially well suited for use in production
machines. Thanks to their large possible
inside diameter, low-profile dimensions andcompact design, these encoders are ideal
for the following:• The C axis on lathes• Rotary and tilting axes
• Auxiliary axes or spindle orientation on
milling machines

RCN 8511 absolute angle encoder

For detailed information about the angle
encoders without an integrated bearing,please visit www.heidenhain.com.

5Selection guide
Absolute angle encoders with an integral bearing and hollow shaft

SeriesMain dimensions
in mm

Systemaccuracy

Mechanicallypermissible
speed1)

Position values per
revolution

Interface

Incremental
signals

Signal periods/ Model
revolution

Further
information±4”

 1500 rpm

67 108 864  26 bits

EnDat 2.2

» 1 VPP

16 384

RCN 2381

Page 38

EnDat 2.2––

RCN 2311

Fanuc Þi––RCN 2391 F

Mitsubishi––

RCN 2391 M

Panasonic––

RCN 2391 P

EnDat 2.2

» 1 VPP

16 384

RCN 2581

EnDat 2.2––

RCN 2511

Fanuc Þi––RCN 2591 F

Mitsubishi––

RCN 2591 M

Panasonic––

RCN 2591 P

EnDat 2.2

» 1 VPP

16 384

RCN 5381

EnDat 2.2––

RCN 5311

Fanuc Þi––RCN 5391 F

Mitsubishi––

RCN 5391 M

Panasonic––

RCN 5391 P

EnDat 2.2

» 1 VPP

16 384

RCN 5581

EnDat 2.2––

RCN 5511

Fanuc Þi––RCN 5591 F

Mitsubishi––

RCN 5591 M

Panasonic––

RCN 5591 P

EnDat 2.2

» 1 VPP

32 768

RCN 8381

EnDat 2.2––

RCN 8311

Fanuc Þi––RCN 8391 F

Mitsubishi––

RCN 8391 M

Panasonic––

RCN 8391 P

 750 rpm

EnDat 2.2

» 1 VPP

32 768

RCN 8581

 1500 rpm(¬ 60 mm)
 1200 rpm(¬ 100 mm)

EnDat 2.2––

RCN 8511

Fanuc Þi––RCN 8591 F

Mitsubishi––

RCN 8591 M

Panasonic––

RCN 8591 P

With integrated stator coupling2)

RCN 2001

 3000 rpm±2”

 1500 rpm

268 435 456  28 bits

 3000 rpm

2)

±4”

RCN 5001

 1500 rpm

67 108 864  26 bits

 2000 rpm±2”

 1500 rpm

268 435 456  28 bits

 2000 rpm

2)

±2”

RCN 8001

 750 rpm
 1500 rpm(¬ 60 mm)
 1200 rpm(¬ 100 mm)

60

±1”

1)
2)

6

536 870 912  29 bits

RCN 2001¬ 20 mm

Page 42

Page 46

RCN 5001¬ 35 mm

RCN 8001¬ 60 mm

RCN 8001¬ 100 mmSee permissible shaft speeds on Page 26/27 and in the relevant encoder Specifications
Also available with functional safety7Selection guide
Absolute angle encoders with an integral bearing and a hollow shaft

SeriesMain dimensions
in mm

System accuracy Mechanicallyperm. speed

Position values per
revolution

Interface

Incremental
signals

Signal periods/ Model
revolution

Further
information

 200 rpm 2)

268 435 456  28 bits

EnDat 2.2–

19 998

Fanuc Þi–RCN 6390 F

RCN 6000
Product
Information
document

Mitsubishi–

RCN 6390 M

EnDat 2.2

» 1 VPPWith mounted stator coupling
1)

±2”
Ø 292

RCN 600044

RCN 200

ECN 2000

1)
2)

8

Ø 180

±6“

±10”

 3000 rpm

 3000 rpm

33 554 432  25 bits

33 554 432  25 bits

2048

RCN 6310

RCN 280

EnDat 2.2

RCN 210

Fanuc ÞiRCN 290 F

Mitsubishi

RCN 290 M

EnDat 2.2

» 1 VPP2048

ECN 2180

EnDat 2.2––

ECN 2110

Fanuc Þi––ECN 2190 F

Mitsubishi––

ECN 2190 M

RCN 200
Product
Information
document

RCN 6000¬ 180 mm

RCN 200¬ 20 mm

ECN 2000
Product
Information
document

ECN 2000¬ 50 mm

Also available with functional safety
Higher shaft speeds possible depending on the operating temperature (see relevant Product Information document)

9Selection guide
Incremental angle encoders with an integral bearing and hollow shaft

SeriesOverall dimensions
in mm

System accuracy

Mechanically permissible
speed1)

Interface

Signal periods/
revolution

Model

Further
information±5”

 3000 rpm« TTL

180 000/90 000

RON 275» 1 VPP

18 000

RON 285» 1 VPP

18 000

RON 287

RON 200/
RON 700/
RON 800/
RPN 800
Product
Information
document

With integrated stator coupling
RON 200±2.5”
RON 700

RON 800
RPN 800

1)
2)

±2”

±1”

 1000 rpm

 1000 rpm

2)» 1 VPP

18 000

RON 785» 1 VPP

18 000/36 000

RON 786» 1 VPP

36 000

RON 886» 1 VPP

180 000

RPN 886

RON 200¬ 20 mm

RON 700
RON 800
RPN 800¬ 60 mmMay be limited during operation due to electrically permissible shaft speed
With integrated interpolation

10

11

Selection guide
Absolute and incremental angle encoders with an integral bearing
for a separate shaft coupling
SeriesMain dimensions
in mm

System accuracy Mechanicallypermissible
speed1)

Position values per
revolution

Interface

Signal periods/
revolution

Model

Further
information±5”

67 108 864 (26 bits)

EnDat 2.2

16 384

ROC 2380

EnDat 2.2–

ROC 2310

Fanuc Þi–ROC 2390 F

ROC 2000/
ROC 7000
Product
Information
document

Mitsubishi–

ROC 2390 M« TTL

180 0002)

ROD 270» 1 VPP

18 000

ROD 280

EnDat 2.2

16 384

ROC 7380

EnDat 2.2–

ROC 7310

Fanuc Þi–ROC 7390 F

Mitsubishi–

ROC 7390 M

For separate shaft coupling
ROC 2000

ROD 200

ROC 7000±5”±2” 3000 rpm

 10 000 rpm

 3000 rpm–

268 435 456 (28 bits)

ROD 700±2”

 1000 rpm–» 1 VPP

18 000/36 000

ROD 780

ROD 800±1”

 1000 rpm–» 1 VPP

36 000

ROD 880

1)
2)

ROD 200/
ROD 700/
ROD 800
Product
Information
document

ROC 2000
ROD 200

ROC 2000/
ROC 7000
Product
Information
document

ROD 200/
ROD 700/
ROD 800
Product
Information
document

ROC 7000
ROD 700
ROD 800

May be limited during operation due to electrically permissible shaft speed
With integrated interpolation

12

13

Measuring principles
Measuring standard

HEIDENHAIN encoders with opticalscanning incorporate measuring standards
consisting of periodic structures known as
graduations.
These graduations are applied to a carrier
substrate made of glass or steel. For
encoders with long measuring lengths,
steel tape is used as the scale substrate.
HEIDENHAIN manufactures its precision
graduations in the following speciallydeveloped, photolithographic processes:• DIADUR: extremely robust chromiumlines on glass (typical grating period:
20 μm), or three-dimensional chromium
structures (typical grating period: 8 μm)
on glass• METALLUR: contamination-tolerant
graduation consisting of metal lines ongold; typical grating period: 20 μm• SUPRADUR phase grating: opticallythree-dimensional, planar structure;
particularly tolerant to contamination;
typical grating period: 8 μm and finer• OPTODUR phase grating: opticallythree-dimensional, planar structure withparticularly high reflectance; typicalgrating period: 2 μm and finer
Along with the very fine grating periods,
these processes enable high edge
resolution and excellent homogeneity of
the graduation. In combination with thephotoelectric scanning method, thesecharacteristics are critical for attaining highquality output signals.

Absolute measuring method

Incremental measuring method

In the absolute measuring method, theposition value is available immediately
upon encoder switch-on and can berequested by the downstream electronics
at any time. There is therefore no need tosearch for the reference position by jogging
the axes.

With the incremental measuring method,
the graduation consists of a periodic
grating structure. The position information
is obtained by counting the individual
increments (measuring steps) from somepoint of origin. Since the ascertainment of
positions requires an absolute reference,the scales or scale tapes feature an
additional track with a reference mark. The
absolute position on the scale, establishedby means of the reference mark, is gatedwith exactly one measuring step.
The reference mark must therefore be
scanned to establish an absolute referenceor to find the last selected datum.

The absolute position information is readfrom the circular scale, which is designedwith a serial absolute code structure. The
code structure is unique over one revolution.
A separate incremental track is read withthe single-field scanning principle andinterpolated for the position value.

In some cases, this may require rotation by
up to 360°. To simplify reference runs,
many HEIDENHAIN encoders feature
distance-coded reference marks: thereference-mark track has multiple referencemarks at different defined distances. The
downstream electronics determine theabsolute reference point after just twoneighboring reference marks have been
traversed; in other words, after just a few
degrees of rotational motion (see “Nominal
increment N” in the table).
Encoders with distance-coded referencemarks are identified with a “C” following
the model designation (e.g., RON 786 C).
With distance-coded reference marks,
the absolute reference is determined bycounting the increments between two
reference marks.

Line count z

Number ofreference marks

Nominalincrement N

36 00018 000

72
36

10°
20°

Circular scale with serial code track and fine track

The master graduations are manufactured
by HEIDENHAIN on custom-built, highprecision dividing engines.
ZeropositionZeroposition

Schematic representation of a circular scale with distance-coded referencemarks

Absolute and incremental circular scales and scale drums

14

15

Photoelectric scanning

Most HEIDENHAIN encoders utilize thephotoelectric scanning principle.
Photoelectric scanning is touchless andtherefore does not induce wear. Thismethod detects even extremely finegraduation lines down to a width of only
a few micrometers and generates output
signals with very small signal periods.
The finer the grating period of a measuring
standard is, the greater the effect ofdiffraction on photoelectric scanning.
HEIDENHAIN angle encoders use twoscanning principles:• The imaging scanning principle forgraduation periods of 10 µm to approx.
70 µm.
• The interferential scanning principle
for very fine grid lines with graduation
periods of 8 µm, 4 µm and finer.

Imaging principle
Put simply, the imaging scanning principle
functions by means of projected-lightsignal generation: two gratings with equalgrating periods (the circular scale and thescanning reticle) are moved relative to eachother. The carrier material of the scanning
reticle is transparent, whereas thegraduation on the measuring standard may
be applied to a transparent or reflective
surface.
Parallel light passes through a grating
structure, casting dark and light fields at a
certain distance, where there is an index
grating with the same or similar grating
period. When the two gratings move
relative to each other, the incident light ismodulated: If the gaps are aligned, lightpasses through. If the lines of one grating
coincide with the gaps of the other, no lightpasses through.

A wide-surface photocell array converts
these variations in light intensity into
electrical signals. The specially structured
grating of the scanning reticle filters thelight to generate nearly sinusoidal output
signals. The smaller the period of thegrating structure is, the closer and more
tightly toleranced the gap must be
between the scanning reticle and circularscale. In encoders that use the imaging
scanning principle, workable mounting
tolerances are attainable starting at aminimum grating period of 10 μm.
The RCN, ECN, RON, ROC and ROD angle
encoders with an integral bearing use theimaging scanning principle.

Interferential scanning principle
The interferential scanning principle uses
the diffraction and interference of light onfinely divided gratings in order to produce
the signals from which motion ismeasured.
A step grating is used as the measuring
standard: reflective lines just 0.2 µm inheight are applied to a flat, reflective
surface. In front of this is the scanning
reticle—a transparent phase grating withthe same grating period as the scale.
When a light wave passes through thescanning reticle, it is diffracted into threepartial waves of the +1st, 0th, and –1storders, with nearly equal luminous intensity.
The waves are diffracted by the scale
such that most of the luminous intensity
is found in the reflected +1st and –1stdiffraction orders. These partial waves
meet again at the phase grating of thescanning reticle, where they are diffracted
again and interfere. This produces
essentially three waves that leave thescanning reticle at different angles.
Photocells convert these alternating lightintensities into electrical signals.

When there is relative motion between
the scale and the scanning reticle, thediffracted wavefronts undergo a phaseshift: movement by the amount of one
grating period shifts the positive first-orderdiffraction wavefront by one wavelength in
the positive direction, while the negative
first-order diffraction wavefront is displacedby one wavelength in the negative direction.
Since the two waves interfere with eachother when exiting the grating, the waves
are shifted relative to each other by two
wavelengths. This relative motion over one
grating period therefore results in two
signal periods.
Interferential encoders use averagegrating periods of 8 µm, 4 µm and finer.
Their scanning signals are largely free of
harmonics and can be highly interpolated.
These encoders are therefore especiallywell suited for high resolution and highaccuracy. At the same time, their generous
mounting tolerances permit installation intoa wide range of applications.
The RPN 886 angle encoder with an
integral bearing uses the interferential
scanning principle.

Interferential scanning principle (optical diagram)
C Grating periody Phase shift of the light wave when passing through the scanning reticle
 Phase shift of the light wave through the X motion of the scale

Imaging scanning principle

LED light source
Photocells
Condenser

LED
light source
Condenser

Scanning reticle
Measuring standard
Scanning reticle
Photocells

Photocells I90°
and I270° not
shown

16

Measuring standard

17

Measurement accuracy
Calibration chart

The accuracy of angular measurement ismainly determined by:• The quality of the graduation• The quality of the graduation carrier• The quality of the scanning process• The quality of the signal processing
electronics• The quality of the encoder mechanics• The eccentricity of the graduation
relative to the bearing• The bearing errors• The method of coupling to the measured
shaft; in the case of angle encoders withan integral bearing, for example, this is
the stator coupling (RCN, ECN, RON,
RPN) or the shaft coupling (ROC, ROD)
These factors can be subdivided into
encoder-specific position errors andapplication-dependent factors. For
assessment of the attainable overall
accuracy, all of these individual factors
must be taken into account:

Encoder-specific position error
The encoder-specific error includes:• The accuracy of the measuring standard• The interpolation accuracy• The position noise• The quality of the encoder’s mechanicaldesignThe accuracy of the measuring standard
The accuracy of the measuring standard isprimarily dictated by the homogeneity of
the graduation.

It is stated as the maximum value of thebaseline error. The distance between themeasuring points is equivalent to theinteger multiple of the signal period. As aresult, interpolation errors have no effect.
Interpolation accuracy
The interpolation error has an effect evenat very low traversing speeds and causes
speed fluctuations, especially in the speed
control loop. Within the application, theinterpolation error affects the machining
quality, such as the surface quality.
The interpolation accuracy is primarily
influenced by:• The fineness of the signal period• The homogeneity and period resolutionof the graduation• The quality of the scanning filter
structures• The characteristics of the sensors• The quality of the signal processing
The interpolation accuracy is stated in theform of a maximum value ±u of theinterpolation error.
Position noise
Position noise causes small, random
deviations from the expected value.
Position noise also depends on the qualityof the signal processing. Typically, theposition noise is less than 1  of the signal
period.
For angle encoders with an integral
bearing, the system accuracy is provided in
the specifications for better differentiation.

Position 

Position error Interpolation error
within one signal
periodApplication-dependent errors
Angle encoders with an integral bearing
and stator coupling (RCN, ECN, RON, RPN)
compensate for movements between therotor and stator that are not in the directionof measurement. Due to this principle ofoperation, very wide mounting tolerances
can be realized with minimal effect on theoverall accuracy.
In the case of angle encoders with aseparate shaft coupling (ROC, ROD), theoverall accuracy of the angular error of thecoupling must be considered as well (seeMechanical design types and mounting:
ROC, ROD).
In the case of encoders without an
integral bearing, the mounting andadjustment of the scanning head have asignificant effect on the attainable overall
accuracy. Of particular importance are boththe mounting eccentricity of the graduationand the radial runout of the measured
shaft. Evaluation of the overall accuracyof these encoders requires that theirapplication-dependent errors be individually
measured and taken into account (see theAngle Encoders without Integral Bearing
brochure).

For angle encoders with an integral bearing,
HEIDENHAIN creates quality inspection
documents included with the encoder.
The quality inspection document states
the system accuracy, which is determinedthrough five forward and five reverse
measurements during final inspection. The
measuring positions per revolution are
selected such that both the baseline error
and the interpolation error are recordedwith great accuracy. The mean value curveshows the arithmetic mean of the measured
values. The reversal error is not included.
The mechanical hysteresis depends on
the shaft coupling. For angle encoders witha stator coupling (RCN, ECN, RON and RPN),
it is determined at ten measuring positions
during the step cycle. The maximum value
and arithmetic mean are documented on
the calibration chart. The following limits
apply to this hysteresis:
RCN 2xxx/RON 2xx:		
RCN 5xxx:			
RCN 2xx/ ECN 2xxx:		
RON 7xx:			
RCN 8xxx/RON/RPN 8xx:
RCN 6xxx:			

≤ 0.6”≤ 0.6”≤ 2”≤ 0.4”≤ 0.4”≤ 0.8”

By including the calibration standard,
the quality inspection document establishes
the link to national and international
standards and ensures traceability. The
measuring parameters and the measure­ment uncertainty are also provided.

Interpolation accuracy

Signal level Position error 

The accuracy of the measuring standard

The system accuracy defines the upper
limit of the position deviations within agiven position. It consists of the baseline
error combined with the interpolation error.
In the case of angle encoders with a stator
coupling (RCN, ECN, RON, RPN), thesystem accuracy also includes the errors of
the shaft coupling.

ExampleInterpolation
error

Determination of the reversal error during the step cycle

Signal period
360 °elec.

Measuring point
Reference mark18

19

Angle encoders for direct drive motors in machine tools

The performance of a direct-drive feed axis
is significantly affected by the choice of
encoder for measuring the axis position.

Amplitude in % Resonances that excite the natural
frequencies of an axis and its assemblies
are usually dampened with filters in the100

RCN 8311

80

Alternative angle
encoder

control loop. However, the use of filters
causes a phase loss in the control loop,
thus reducing the control bandwidth. The
lower the resonance frequency to bedamped is, and the higher the damping
value of the required filter is, the more thecontrol bandwidth and thus the dynamic
performance of the axis is reduced. Thus,in order to attain high control bandwidth,
resonances should have the highest
frequency possible with low amplitude.
As a component of the axis, the encoder
affects the resonance behavior and thus
also the dynamic behavior of the feed unit.
The encoder design and type of shaft
coupling are key factors in attaining good
dynamic behavior for the axis. By way of
example, we now wish to demonstrate
how the behavior of the feed axis isaffected by an RCN 8311 and a mountingcompatible alternative angle encoder ofcomparable accuracy. In order to evaluate
the two angle encoders with regard to theirresonances, radial and axial vibrations were

60
40
20

20

100

500

1000

2000

Frequency in Hz 

Speed controller step response in % Figure 1: Maximum occurring amplitude during radial and axial excitation of an RCN 8311 and analternative angle encoder.

100

The RCN 8311 exhibits resonances onlyin the upper frequency range, and theseresonances have only low amplitudes,
whereas the alternative angle encoder
exhibits disruptive resonances even at low
frequencies.
This difference in frequency behavior has asignificant effect on the controller behaviorof a direct-drive motor. This can be seen,for example, through a step response in theshaft-speed control loop. Taking comparable
controller settings regarding amplitudes
and phase reserves into account, Figure 2
shows the step response in the shaft-speed
control loop for the same rotary axis unit
with the two angle encoders.
With the RCN 8311, the nominal speed isachieved faster with lower overshoot thanby the alternative angle encoder. This isbecause resonance points of the RCN 8311
do not occur until high frequencies andthen at only low amplitudes. As a result,filters are used only at high frequencies
with low damping values, thereby barely
affecting the control bandwidth. And in thecase of the alternative angle encoder, aharmonic can also be seen during the step
response in Figure 2. This harmonic is basedon the natural frequency of this encoder inthe range between 100 Hz and 200 Hz.
Achieving high dynamic performance witha direct-drive feed axis requires an encoderwith a natural frequency that is as high as
possible. Various design measures weretaken for the RCN series that achieve
excellent vibration behavior, such as theirmounting design and shaft coupling. This
enables high dynamic performance for the
direct-drive rotary axis, enabling faster andmore consistent part manufacturing andultimately improving the productivity ofmachining centers.

In addition, thanks to its optical scanning
method, the RCN series offers strong
benefits for direct-drive feed axes in termsof accuracy, running smoothness andtemperature behavior. On direct-drive feed
axes, the encoder measures both theactual position and the current speed. Dueto the absence of mechanical transmission
elements between the encoder and the
motor, the encoder must provide sufficiently
high resolution in order to attain high-quality
speed control at low feed rates. And here
is another consideration: Higher kV factors
in the position control loop of direct-drive
motors permit wider control bandwidths
and allow the servo stiffness to be tuned.
But this also magnifies the influence of theencoder’s signal quality on positioning andcontrol-loop behavior. Position errors within
one signal period adversely affect thepositioning accuracy and speed stability ofthe motor. At low feed rates, the feed
motor, and thus the rotary axis, reproduce

Position controller

the position errors within one signal period.
Because direct drive motors exhibit a wider
control bandwidth due to the higher kV factor,
they reproduce these position errors overa wider speed range of the feed axis.
The speed controller calculates the nominal
currents that brake or accelerate the motorin accordance with the control error.
Inadequate encoder signal quality in the
direct-drive axis causes disturbances in theposition control loop and in the underlying
control loops, extending as far the current
control loop. This leads to high noise levelsin the motor current signal and, in especiallybad cases, to unwanted high-frequency
noise in the power train. The loop gain
must be reduced. The high noise also
causes increased power dissipation in the
motor. This results in greater heat build-up
within the axis unit. Thermally induced
deformations in the axis structure mayarise, or greater machine cooling

performance may be required. To avoid
these problems, direct-drive feed axes callfor position encoders with small signal
periods and high signal quality.
The RCN series features a high line countand high signal quality. With these encoders,
direct-drive rotary axes exhibit low motor
current noise and smooth operating
behavior. The high signal quality of opticalencoders therefore permits better use of
the performance potential of direct-drive
feed axes.

Speed controller

Motor

Angle encoder

Control loop with a rotary direct-drive motor (torque motor)

75

50
RCN 8311

25

0Alternative angle
encoder00

t1 t2Time in s Figure 2: Step response in the shaft speed control loop subject to control with an RCN 8311 and analternative angle encoder

20

induced in the range of 20 Hz to 2000 Hz
by means of a shaker. Figure 1 shows theresults (the maximum occurring amplitude
is equivalent to 100% in the graph).

Motor current in A 

Direct drive motors are being increasingly
used in many fields, particularly in themachine tool industry. Compared withgeared rotary axes, direct drive motors are
extremely low-wear and low-maintenance.
Without intervening mechanical transmission
components, torque motors also enablesignificantly higher dynamic performance ofthe rotary axes. Thanks to their direct torquedelivery, significantly higher accelerations
and shaft speeds can be attained. This isparticularly beneficial in 5-axis simultaneousmachining, where it is typically the rotary
axes that limit the speed of simultaneous
motion. Higher dynamic performance ofthe rotary axes translates into uniform tool
feed rates and increased productivity.

100

200

300

500

	Optical angle encoder with 32 768 lines

Shaft speed in rpm 	Optical angle encoder with 16 384 lines400

	Non-optical angle encoder with 2600 lines

Example of the noise behavior of optical and non-optical angle encoders in rotary tables with adirect-drive motor at a continuously increasing shaft speed

21Mechanical design types and mounting
RCN, ECN, RON, RPN

RCN, ECN, RON and RPN angle encoders
have an integral bearing, hollow shaft and acoupling on the stator side. The measured
shaft is directly connected with the shaft of
the angle encoder.
Setup
The circular scale is rigidly affixed to thehollow shaft. The scanning unit rides on theshaft on ball bearings and is connected tothe housing with a coupling on the statorside. The stator coupling and the sealing
design greatly compensate for axial andradial mounting errors without restricting
functionality or accuracy. Particularly with
the RCN, this permits relatively widemounting tolerances and therefore
simplifies the mounting process. During
angular acceleration of the shaft, the stator
coupling must absorb only the torqueresulting from friction within the bearing.
Angle encoders with a stator coupling
therefore provide excellent dynamic
performance.
Mounting
The housing of the RCN, ECN, RON, and
RPN is firmly connected to the mounting
surface of the machine part via a mounting
flange and a centering collar.
The manner of shaft coupling varies
depending on the encoder model. With the
RCN 2001, RCN 5001 and RCN 8001, forexample, a shaft coupling with a ring nut ora front-face shaft coupling is possible.

Further information:
See the relevant Product Information
documents for detailed descriptions of
the RCN 6000, RCN 200 and ECN 2000,
as well as for the RON 200, RON 700,
RON 800 and RPN 800.

22

Ring nut

ROC, ROD

The ROC and ROD angle encoders requirea separate shaft coupling for the rotor-side
coupling. The shaft coupling compensates
for axial movement and misalignment
between the shafts, preventing excessive
load on the bearing of the angle encoder.
For realizing high accuracies, it is necessarythat the shaft of the angle encoder is
optimally aligned with the shaft of themachine. The HEIDENHAIN product portfolio
includes diaphragm couplings and flat
couplings designed for rotor-side couplingof the ROC or ROD angle encoders.
Mounting
The ROC and ROD angle encoders feature
a mounting flange with a centering collar.
The encoder shaft is connected to themachine shaft by means of a diaphragm
coupling or flat coupling.

Example: mounting an angle encoder with a ring nut

Rotary table

Additional
protection fromdripping fluids

Mounting example
ROC 7380

ROC 7380

Shaft
coupling

ROC, ROD
Centering collar

Shaft couplings
The shaft coupling compensates for axial
movement and misalignment between theencoder shaft and the measured shaft,thus preventing excessive loading on the
bearing of the angle encoder.

Flat coupling

Radial offset l
Angular error aMounting an ROC
or ROD witha flat coupling

Axial motion dFurther information:
Refer to the relevant Product Information
document for a detailed description of
the ROC 2000/ROC 7000 and ROD 200/
ROD 700/ROD 800.

23

Benefits of the RCN 2001, RCN 5001 and RCN 8001
The new standard: fast and smart

Angle encoders from HEIDENHAIN havelong been the gold standard wheneverangular measurement is needed on rotarytables and tilting axes. With the RCN 2001,
RCN 5001 and RCN 8001 absolute angle
encoders, for example, HEIDENHAIN offers
the ideal solution for position measurementin the field of machine tools, including forsafety-related applications.
High positioning accuracy
Proper encoder selection contributes
significantly to the measurement of an axis
position and thus to the machining accuracy.
But when it comes to attaining optimalaccuracy, it’s important to consider not only
the encoder-specific characteristics but also
factors such as how well the encoder ismounted and adjusted. This is where theintegrated bearing and stator coupling of
the RCN series give them an important
advantage over other encoders. Thus, alongwith encoder-specific error, such as theaccuracy of the measuring standard or theinterpolation accuracy, the error present
in the coupling to the measured axis isincluded, and the system accuracy can be

specified. The RCN 2001 and RCN 5001
series are specified with system accuraciesof ±2” and ±4”; the RCN 8001 series
with ±1” and ±2”.
High dynamic performance of therotary axis
High encoder resolutions cause low noisein the motor current and smooth operating
behavior, particularly in the case of directdrive rotary axes. They also have a positiveeffect on control behavior and allow
manufacturers to attain high surface quality
combined with high productivity. The
RCN 2001, RCN 5001 and RCN 8001 series
feature very high resolution based on highline counts and high signal quality. The
RCN 8001 series, for example, has a line
count of 32 768 and provides absolute
position values at a resolution of more than
536 million positions per revolution. For
more information, see Angle encoders for
direct-drive motors in machine tools on
Page 20.
Easy mounting
Another key feature of the RCN series istheir easy mounting. Very little effort isInterpolation error 

Figure 1:
Example of droplet-like contamination on acircular scalerequired. Unlike with other angle encoders,
centering the graduation or electricallytesting the signals prior to initial operation
is not needed. And due to the way the
RCN is designed, relatively large mounting
tolerances are possible without limiting
accuracy or functionality. Axial deviations of
up to ±0.3 mm, for example, are permis­
sible with the RCN 2001, RCN 5001 and
RCN 8001.
High reliability
The scanning functionality of the RCN 2001,
RCN 5001 and RCN 8001 series is so
robust that liquid contamination andcondensation droplets barely have an effecton the scanning signals or motor control.
Droplet contamination on the circular scale,as seen in Figure 1, has almost no effecton the interpolation error (Figure 2). The
predecessor model, the RCN 8000,
exhibited a low level of interpolation error.
This broadly prevents interruptions to themachining process due to encoder con­tamination. A housing and a seal are also
standard features of the RCN series, giving
them an IP64 rating. As a result, sealing air
is no longer needed in most applications,thus having a positive effect on energy andCO2 conservation within the application.

This yields the following benefits:• Reduced cabling• Purely digital transmission technology• Overload protection of the direct-drive
motor through the monitoring of all threewindings• Precise temperature monitoring throughcompensation of the transmission timing
behavior of the temperature measurement(with direct-drive motors from ETEL)• Increased cost efficiency through use of
the direct-drive motor up to its thermalload limit

RCN

EIB 52x1

Example of in-situ processing of direct-drive motor temperatures with an EIB 5211
and RCN 5311.

In-situ processing of direct-drive motor
temperatures
To prevent direct-drive motors from over­heating during operation, their temperature
is typically monitored. In conjunction with
the HEIDENHAIN EIB 52x1 signal converter,
the RCN 2001, RCN 5001 and RCN 8001
series enable simple evaluation of thewinding temperatures of direct-drive

1”

0
–1”

Position 

motors. The EIB 5211 or EIB 5291S signal
converters can be installed near the directdrive motor, where they enable in-situ
digitalization of the temperature information
coming from the direct-drive motor. Alongwith the position data, the RCNs thentransmit the processed temperature data
to the controller via the purely digitalinterface.

Figure 2:
Effect of droplet-like contamination on theinterpolation error (RCN 8001: green; RCN 8000:
red)Standardization and flexibility
It is not uncommon for rotary axes to be
used on different models of controls. In thiscase, they must be able to communicate
with the relevant interfaces. To avoid needingto create different rotary-axis variants, it ispossible to take advantage of standardization.
For this purpose, external signal converters
such as the EIB 3392 S and EIB 3392 F
signal converters in cable design are used.
They convert the purely serial EnDat inter­face of the encoder to the DRIVE-CLiQ and
FANUC interfaces, thus allowing the numberof required variants for the angle encoders
to be reduced. This has a positive effect onwarehouse capacity and increases
flexibility.

Example of a signal converter in cable design (EIB 3392 S)

DRIVE-CLiQ is a registered trademark of Siemens Aktiengesellschaft.

24

25

Shaft speed in rpm

Shaft speed in rpm

Shaft-speed graph as an orientation aid for the RCN 8001 with a hollow shaft (¬ 60 mm)

Shaft speed in rpm

Shaft-speed diagram as an orientation aid for the RCN 2001 series with a purely serial interface

Operating temperature in °C
Shaft-speed diagram as an orientation aid for the RCN 5001 series with purely serial interface

Operating temperature in °C

Shaft-speed graph as an orientation aid for the RCN 8001 with a hollow shaft (¬ 100 mm)

Permissible speed range3)

Permissible speed range3)

Wider speed range, requiring encoder temperature monitoring3)

Wider speed range, requiring encoder temperature monitoring3)

Specification limit (maximum permissible speed and operating temperature)3)

Specification limit (maximum permissible speed and operating temperature)3)

Generation of an alarm bit due to excessive encoder temperature3)

Generation of an alarm bit due to excessive encoder temperature3)

1)

1)

2)

2)

A preset operating parameter that can be changed
At a preset temperature of 86 °C
3)With a purely serial interface

26

Operating temperature in °C

Operating temperature in °C

Shaft speed in rpm

High productivity
In order to machine workpieces with maxi­
mum productivity, a machine tool’s rotary
axes must be operated at high shaft speeds.
In particular, the purely serial interface of
the RCN supports this trend. With theirpurely serial interface, the RCN 2001 and
RCN 5001 series achieve shaft speeds of
up to 3000 rpm, with 1500 rpm possible
for the RCN 8001. The permissible rotational
speed is largely dependent on the internal
encoder temperature, which is affected by
the duration of operation and the operating
temperature. The operating temperature isdefined as the temperature in the immediate
vicinity of the encoder but not at theencoder’s surface. To protect the encoderfrom overheating, the RCN 2001, RCN 5001
and RCN 8001 are equipped with a tem­
perature sensor. This sensor measures
the temperature inside the encoder andtransmits it to the downstream electronics.
If the temperature inside the encoder is toohigh (90 °C), then an alarm is generated, andthe machine controller initiates appropriate
measures to protect the encoder fromdamage. When the EnDat interface is used
and the temperature inside the encoder
reaches 86 °C, a warning bit1) is set inadvance. This bit can be used to trigger
individualized machine actions and avoid
interruption of the machining process.
Speed diagrams were created throughanalyzing the encoder temperatures fromtests at different operating temperaturesand shaft speeds. These diagrams show
the permissible shaft speeds as a functionof the operating temperature (valid for up
to 90 minutes of uninterrupted operation).
As a function of the operating temperature,
the green areas represent the permissible
shaft speeds at which temperatures inside
the encoder are non-critical. In the yellow
areas, the combination of speed andoperating temperature already yield sucha high encoder temperature that the
EnDat interface generates a warning bit.2)
At the red lines, the encoder temperature
is 90 °C, and an alarm bit is set for an
excessive temperature.

A preset operating parameter that can be changed
At a preset temperature of 86 °C
3)With a purely serial interface

27

Functional safety

Safe axes
Driven axes on machine tools usually
represent a significant hazard for humans.
It must be ensured that the machine does
not make any uncontrolled movements,
especially when a person is interactingwith the machine (e.g., workpiece setup).
This requires position information about theaxes for proper implementation of safetyfunction. As an evaluating safety module,
the controller has the task of detecting
faulty position information and reacting toit accordingly.
Various safety strategies can be pursued
depending on the topology of the axis andthe evaluation capabilities of the controller.
In a single-encoder system, for example,
only one encoder per axis is evaluated forthe safety function. But on axes with two
encoders, such as a rotational axis with arotary encoder and an angle encoder, thetwo redundant position values can becompared with each other in the controller.
Safe fault detection can be ensured only if
the controller and the encoder are properly
matched to each other. It must be notedthat the safety designs of controller manufacturers differ from one another. As a result,
the requirements to be fulfilled by the­connected encoders may also differ to an
extent.

Type-examined encoders
HEIDENHAIN angle encoders with an
integral bearing are used successfully on
different controls in a wide variety of safety
designs. Particularly noteworthy in thiscontext are the type-tested RCN 2001/
RCN 5001/RCN 8001 encoders with the
EnDat interface. These encoders can be
operated as single-encoder systems inconjunction with a suitable controller inapplications with the controller category
SIL 2 (as per EN 61508) or performancelevel “d” (as per EN ISO 13849). Unlike
incremental encoders, the RCN 2001/
RCN 5001/RCN 8001 absolute angle
encoders provide a safe absolute position
value at all times, including immediately
after switch-on or after a power outage.
Reliable position transmission is based on
two independently generated absolute
position values and on error bits provided
to the safe controller. The purely serial datatransmission also provides other benefits,
including greater reliability, improved
accuracy, diagnostic capabilities, and reduced
costs through simpler connection technology.

Standard encoders
In addition to those encoders explicitly
qualified for safety applications, standard
angle encoders (e.g., with a Fanuc interface
or 1 VPP signals) can be used in safe axes.
In such cases, the characteristics of theencoders must be matched to the require­ments of the given controller. For thispurpose, HEIDENHAIN can provide additional
data about the individual encoders (failurerate, fault model as per EN 61800-5-2).
Service life
Unless otherwise specified, HEIDENHAIN
encoders are designed for a service life of
20 years (as per ISO 13849).

Safe encoder

Fault exclusion is thereby possible for theloosening of the mechanical connection
between the encoder and the machine
shaft or customer fastening components.

For designing the mechanical fault
exclusion for other purely customer-sideconnections, the following encoder torquemust be taken into account:
MMax = J · Þ + MFriction
J:	Moment of inertia of the encoder (rotor
or stator; see the specifications) and of
the mechanical connection (e.g., ringnut and catch when acceleration isapplied via the hollow shaft, and theshaft is coupled via these components)
Þ:	Maximum angular acceleration in theapplication
MFriction: RCN 2001/RCN 5001:
RCN 8001 ( 60 mm):
RCN 8001 ( 100 mm):

The safety-related characteristic values
are listed in the encoder specifications.
These characteristic values are explainedin the Technical Information document
Safety-Related Position Encoders.

4.5 Nm
7.5 Nm
8.5 NmMechanicalconnection

Fastening

Safe position for themechanical connection2)

Limited specifications3)

Housing/flange

RCN 2001/5001: M4 ISO 4762 8.8 screws
RCN 8001:		 M5 ISO 4762 8.8 screws±0°

See Permissible angularaccelerations in Mounting
and accessories

1)

Hollow shaft
Ring nut and catch (see Mounting)
Shaft coupling withring nut
Hollow shaft
Front-faceshaft coupling

Mechanical connection

There are various ways of connecting theRCN 2001, RCN 5001 and RCN 8001 series
for providing this kind of fault exclusion.
Whereas the housing or flange is normallyfastened with screws, special factors must
be considered for the hollow shaft
connection. For more information on this
topic and on deviating specifications,please refer to the following table.

Further information:

For the use of standard encoders insafety-related applications, HEIDENHAIN
can also provide additional information
about individual products (failure rate,
fault model as per EN 61800-5-2).

Electrical connection

Fault exclusion for the loosening of themechanical connection
Along with an encoder’s data interface,its mechanical connection to the motor isalso safety-relevant. In table D8 of the
EN 61800-5-2 standard for electrical
power drive systems, the loosening of themechanical connection between theencoder and the motor is listed as a fault
that requires consideration. Since it cannot
be guaranteed that the controller willdetect such errors, fault exclusion for theloosening of the mechanical connection isrequired in many cases.

RCN 2001: ±0.55°
RCN 5001: ±0.35°
RCN 8001:  60 mm: ±0.15°
 100 mm: ±0.10°

RCN 2001/5001:	ISO 4762 8.8 M3 screws
RCN 2001: ±0.07°
ISO 8752 – 2.5x10 – St spring pins RCN 5001: ±0.06°
RCN 8001:		M4 ISO 4762 8.8 screws
RCN 8001: ±0.02°
ISO 8752 – 4x10 – St spring pins

1)

A suitable anti-rotation lock must be used for the screw connections (mounting/servicing)
Fault exclusion is granted only for the explicitly mentioned mounting options
3)
Unlike mounting without mechanical fault exclusion for the loosening of the mechanical connection
2)

Safe controller

Safety-related position
measuring system

Safety-related position measuring system with mechanical connection and electrical interface

Further information:
Adhere to the information in the following documents to ensure the correct andintended operation of the encoder:• Mounting Instructions
RCN 2xx1		
1307424 / 1307425
				RCN 5xx1		
1307426 / 1307427
				RCN 8xx1		 1307428 / 1307429 / 1307430 / 1307431• Technical Information: Safety-Related Position Measuring Systems
596632For implementation in a controller:• Specification for the Safe Controller			

2853309529

Mounting and accessories
RCN 2001, RCN 5001 and RCN 8001 with mechanical fault exclusion

The housing of the RCN is firmly connectedto the mounting surface of the machinecomponent via a mounting flange andcentering collar.
Shaft coupling with ring nut
During mounting, the hollow shaft of theangle encoder is press-fitted onto themachine shaft. The catch, which is addedfrom above to the encoder face, implements
the fault exclusion for the loosening of themechanical connection between theencoder and the motor. Fastening is thenperformed with the ring nut, which can beeasily tightened with the mounting aid. (foraccessories and their moment of inertia,
see Accessories on Pages 33 to 35).

Materials to be used
The materials stated in this table must be
used for the machine shaft and fastening
components.
Catch

Mounting aid
Ring nut

Shaft coupling with ring nut and catch (RCN 2001 as example)

Front-face shaft coupling
Particularly in the case of rotary tables, theangle encoder must be integrated into thetable so as to be fully accessible when therotor is lifted. The hollow shaft is connected
through the front-face threaded holes bymeans of special mounting elements
made for the given design (not included indelivery). For compliance with the radial
runout and axial runout tolerances, theinside hole and the plane surfaces must be
used as mounting surfaces for the frontface shaft coupling. Fault exclusion for theloosening of the mechanical connection
between the encoder and the motor isachieved with additional spring pins.

30

Mounting element(adapted to the design)
Spring pins
(2x ISO 8752-2.5x10-St.)

Permissible angular accelerations for
shaft coupling with mechanical fault
exclusion
Based on where acceleration is applied andthe type of mounting, the following values
apply to angular acceleration:• Permissible angular acceleration of therotor when acceleration is applied via thehollow shaft, and the shaft is coupledwith a ring nut and catch:
RCN 2001 series: 
20 000 rad/s2
RCN 5001 series: 
25 000 rad/s2
RCN 8001 series:–  60 mm: 4500 rad/s2–  100 mm: 3500 rad/s2• Permissible angular acceleration of therotor when acceleration is applied via thehollow shaft, and the shaft is coupled to
the front face with fastening screws andspring pins:
RCN 2001 series: 
5500 rad/s2
RCN 5001 series: 
10 000 rad/s2
RCN 8001 series:–  60 mm: 3000 rad/s2–  100 mm: 3000 rad/s2

Mating shaft

Mating stator

Material

Ferrous materials (steel/cast iron materials)

Tensile strength Rm

 600 N/mm2

 250 N/mm2

Shear strength τB 390 N/mm2

 290 N/mm2

Interface pressure pG

 660 N/mm2

 275 N/mm2

Elastic modulus E

110 000 N/mm to 215 000 N/mm

Coefficient of expansionÞtherm (at 20 °C)–6 –1
10 · 10 K to
17 · 10–6 K–1

Mounting temperature

All information regarding screw connections is based ona mounting temperature of 15 °C to 35 °C

2

2• Permissible angular acceleration of thestator when acceleration is applied via
the flange/housing:RCN 2001 series: 
4000 rad/s2
RCN 5001 series: 2500 rad/s2
RCN 8001 series:–  60 mm: 1000 rad/s2–  100 mm: 1000 rad/s2

Front-face shaft coupling (RCN 2001 as example)

31

RCN 2001, RCN 5001 and RCN 8001 series without mechanicalfault exclusion

Accessories

The housing of the RCN is firmly connectedto the mounting surface of the machinecomponent via a mounting flange and acentering collar.

CatchIn order to ensure mechanical fault exclusion
for the loosening of the mechanicalconnection between the encoder and themachine shaft, a catch must be used forthe shaft coupling via ring nuts.

Ring nut
Mounting aid

Shaft coupling with ring nut
For installation, the hollow through shaftof the angle encoder is seated onto themachine shaft and fastened from theencoder’s front face with a ring nut. The
ring nut can be easily tightened by meansof the mounting tool (see Accessories).

Front-face shaft coupling
The hollow shaft is connected through thefront-face threaded holes by means ofspecial mounting elements made for the
given design (not included in delivery). For
compliance with the radial runout and axial
runout tolerances, the inside hole andplane surfaces must be used as mounting
surfaces for the front-face shaft coupling.

Catch for RCN 2001:
ID 817921-01
Catch for RCN 5001:
ID 817921-02
Catch for RCN 8001:– Hollow shaft ( 60 mm):  ID 817921-03– Hollow shaft ( 100 mm): ID 817921-04
Shaft coupling with ring nut (RCN 2001 as example)

D (mm)

Moment of inertia ofring nut and catch

29.6

4.8 · 10kgm2

RCN 500145.8–624 · 10kgm2

RCN 8001 (¬ 60 mm)

70

87 · 10–6 kgm2

RCN 8001 (¬ 100 mm)

114

550 · 10–6 kgm2

RCN 2001

Mounting element(adapted to the design)–6

Catch for the RCN 2001/RCN 5001/RCN 8001

Ring nut
For fastening on the shaft side,
HEIDENHAIN offers a special ring nut that,with low axial play, smoothly rotates alongwith the shaft thread. This ensures that theload is evenly distributed over the shaft
connection and prevents adverse loadingon the angular encoder’s hollow shaft.
Front-face shaft coupling (RCN 2001 as example)

Permissible angular accelerations
The permissible angular acceleration of therotor and stator is 1000 rad/s2.

Mating shaft

Mating stator

Material

Ferrous materials (steel/cast iron materials)

Tensile strength Rm

 600 N/mm2

 250 N/mm2

Shear strength τB 390 N/mm2

 290 N/mm2

Interface pressure pG

 660 N/mm2

 275 N/mm2

Elastic modulus E

110 000 N/mm to 215 000 N/mm

2

–6Ring nut for the RCN 2001: ID 336669-03
Ring nut for the RCN 5001: ID 336669-17
Ring nut for the RCN 8001:– Hollow shaft ( 60 mm):  ID 336669-11– Hollow shaft ( 100 mm): ID 336669-16*) Pitch diameter
Ring nut for the RCN 2001

2

–1

Coefficient of expansionÞtherm (at 20 °C)

10 · 10 K to
17 · 10–6 K–1

Mounting temperature

All information regarding screw connections is based ona mounting temperature of 15 °C to 35 °C

Ring nut
for

L1

L2

D1

D2

D3

B

RCN 5001¬ 46±0.2¬ 40(¬ 34.052±0.075)¬ 34.463±0.053(¬ 35.24)

1

RCN 8001¬ 70±0.2
Hollow shaft
¬ 60

¬ 65

(¬ 59.052±0.075)¬ 59.469±0.059(¬ 60.06)

1

RCN 8001¬ 114±0.2 ¬ 107 (¬ 98.538
Hollow shaft±0.095)¬ 100(¬ 99.163±0.07)(¬ 100.067) 1.5

 

Materials to be used
The materials stated in this table must be
used for the machine shaft and fastening
components.

*) Pitch diameter

32

33

Mounting tool for HEIDENHAIN ring nuts
The mounting tool is used for tightening
the ring nut. The tool’s pins lock into theholes of the ring nut. A torque wrenchallows the ring nuts to be tightened withthe required tightening torque.

In-situ measurement of a direct-drive motor

Mounting tool for
RCN 2001:			
ID 530334-03
RCN 5001:			
ID 530334-17
RCN 8001:– Hollow shaft  60 mm: ID 530334-11– Hollow shaft  100 mm: ID 530334-16

EIB 5211

EIB 5281

Mounting in an electrical cabinet

EIB 5291S

Control

EIB 5181

EIB 3392 S signal converter incable design
The EIB 3392 S allows encoders with the“EnDat22” ordering designation to beconnected to the DRIVE-CLiQ interface.
With the EIB 3392 F, the Fanuc interface
can be connected (resolution only as per
operation with the Fanuc Þi Interface).

Temperature sensors

DQ01/Fanuc05

2

3

DQ01: Ø 6.8
Fanuc05: Ø 6

1

EnDat 2.2
EnDat 2.1
1 VSS

Further information:
Example of an EIB 3392 S

EIB 5000 signal converter for measuring
temperature at the direct-drive motor
The EIB 5000 series enables the tempe­
rature measurement of direct drive motors.
To do so, the EIB 5000 boxes process values
from up to three temperature sensors andcompensate for the transmission timing
behavior of the temperature measurement(for direct-drive motors from ETEL). The
maximum determined temperature isrelayed to the upstream control. When thesensor box is used with a HEIDENHAIN
encoder, the processed temperature
values can be transmitted to the upstream
control along with the position data. The
control can use the temperature values tooptimize the regulation of the direct-drive
motor, thus ensuring rapid shutoff in theevent of an overload.
The EIB 5000 series covers variants for use
in an electrical cabinet (IP20) and for in-situ
temperature measurement at the directdrive motor (IP65).

34

Direct-drive motors

For a detailed description of the externalinterface boxes in cable design, refer tothe EIB 3392 S and EIB 3392 F Product
Information documents.

Adapter cable between the RCN 2001/RCN 5001/RCN 8001 and EIB 5211 or EIB 5291 S

Encoderinterface

Downstream electronics
interfaceEIB 5000 version

EnDat22

EnDat22

EIB 5211 (IP64)
EIB 5181 (IP20); only for the
HEIDENHAIN control

Adapter cable with
12-pin M12 quick connector and12-pin M12 coupling (male)

EnDat22

DRIVE-CLiQ

EIB 5291 S (IP64); with a signal converter

1)

Fanuc05

Fanuc05

EIB 5211 (IP64)

EnDat02

EnDat02

EIB 5281 (IP64)
EIB 5181 (IP20)

PUR adapter cable¬ 6 mm; 4 × (2 × 0.09 mm2) + (4 × 0.16 mm2); AP = 2 × 0.16 mm21249072-xx1)

Maximum cable length: 6 m
AP: Cross section of power supply lines¬: Cable diameter (for bend radii, see the Interfaces of HEIDENHAIN Encoders brochure)
DRIVE-CLiQ is a registered trademark of Siemens Aktiengesellschaft.

Further information:
For a detailed description of the signal
converters for temperature measurement
on direct-drive motors, refer to the
EIB 5000 Product Information document.

35

General information
For the RCN, ECN, RON, RPN, ROC and ROD angle encoders

Protection rating
Unless otherwise stated, all RCN, ECN,
RON, RPN, ROC and ROD encoders fulfill
an IP64 protection rating in accordancewith EN 60529 or IEC 60529.
Splash water must not contain any
substances that would have harmful effects
on the encoder’s parts. If the standard IP64
protection rating is insufficient, such as forthe shaft inlet when an angle encoder isinstalled vertically, then the devices should
be protected by additional design measures
such as labyrinth seals.
The RCN, RON, RPN, ROC and ROD angle
encoders are provided with a compressed
air connection. Connection to a source ofcompressed air slightly above atmosphericpressure generates sealing air and provides
additional protection from contamination.
The compressed air introduced directly
into the encoders must be cleaned by amicrofilter and must comply with thefollowing quality classes as per ISO 8573-1(2010 edition):• Solid contaminants:
Class 1
Particle size:
Number ofparticles per m3
0.1 µm to 0.5 µm
 20 000
0.5 µm to 1.0 µm
 400
1.0 µm to 5.0 µm
 10• Max. pressure dew point: Class 4(pressure dew point at 3 °C)• Total oil content:
Class 1
(max. oil concentration 0.01 mg/m3)

Accessory:
DA 400 compressed air unit
ID 894602-01
DA 400HEIDENHAIN offers the DA 400
compressed-air filter system for purifying
the compressed air. It is designed
specifically for conducting compressed air
into encoders.
The DA 400 consists of three filter stages(prefilter, microfilter, and activated carbon
filter) and a pressure regulator with amanometer. The sealing air function can beeffectively monitored using a manometerand a pressure switch (available as anaccessory).
The compressed air introduced into the
DA 400 must fulfill the requirements of thefollowing purity classes as per ISO 8573-1(2010 edition):

Necessary for connection to angle
encoders:
Connecting piece
For tubing 6 x 1
With throttle and gasket
For air-flow rate: 1 l/min to 4 l/min
ID 207835-04
Also suitable:
Swiveling screw fitting (90°)
With seal
ID 207834-02

Further information:
For more information, ask for our DA 400
Product Information document• Solid contaminants:
Particle size:

Class 5
Number ofparticles per m3
0.1 µm to 0.5 µm
Not specified
0.5 µm to 1.0 µm
Not specified
1.0 µm to 5.0 µm
 100 000
• Max. pressure dew point: Class 6(pressure dew point at 10 °C)• Total oil content:
Class 4(max. oil concentration: 5 mg/m3)

The operating temperature range
indicates the ambient temperature limits
between which the angle encoders willfunction properly. The operating temperature
is defined as the temperature in theimmediate vicinity of the encoder but not
at the encoder’s surface.
The storage temperature range of –20 °C
to 60 °C applies when the unit remains in
its packaging. For the RPN 886 and RON
905, a storage temperature of –10 °C to
50 °C must not be exceeded.
Protection against contact
Rotating parts (e.g., shaft couplings with
the ROC and ROD, ring nuts for the RCN,
ECN, RON and RPN) must be sufficiently
protected from unintended contact during
operation.
Acceleration
Angle encoders are subject to various
types of acceleration during operation andmounting.
• The permissible angular accelerationof the rotor and stator for the RCN/ECN/
RON/RPN angle encoders is 1000 rad/s2.
To some extent, higher values apply to
the RCN with fault exclusion for theloosening of the mechanical connection(see the chapters about mounting foreach series).
With the ROC and ROD angle encoders,the permissible angular acceleration
varies depending on the shaft coupling
and the mating shaft (more details uponrequest).
• The abovementioned extreme values
for the vibration resistance apply tofrequencies of 55 Hz to 2000 Hz(EN 60068-2-6), except when mechanicalresonances occur.
• The maximum values for the permissible
acceleration (sinusoidal shock) forshock and impact loads apply at 6 ms
(EN 60068-2-27). During transport, theymust not be higher than 1000 m/s2 (ROD
780/880: 300 m/s2). The corresponding
values for operation are listed in thespecifications.
Under no circumstances should a hammer
or similar implement be used to align theencoder.

For an optimal supply of sealing air to the
angular encoders with an integral bearing,
the required air flow is 1 l/min to 4 l/min
per encoder. Ideally, the air flow is regulatedby the HEIDENHAIN connecting pieces
with an integrated throttle. At an input
pressure of  1 · 105 Pa (1 bar), the throttles
ensure the required air flow rates.

DA 40036

Temperature range
The angle encoders are inspected at areference temperature of 22 °C. The
system accuracy given in the calibration
chart applies at this temperature.

Natural frequency fN of couplingWith the ROC and ROD angle encoders,
the rotor and the shaft coupling together
form an oscillation-capable spring-masssystem. In the case of the RCN, ECN, RON
and RPN angle encoders, this applies tothe stator and stator coupling.
The natural frequency fN should be as
high as possible. For the RCN, ECN, RON
and RPN angle encoders, the respective
specifications state the frequency ranges atwhich the natural frequency of the encoder
does not cause significant position deviationsin the direction of measurement. Ensuring
the highest possible natural frequency for
ROC and ROD angle encoders requires
the use of a shaft coupling with a hightorsional rigidity C.
		

fN = 1 ·2·þ

¹CI

fN: Natural frequency in Hz
C: Torsional rigidity of the shaft coupling in
Nm/radI: Moment of inertia of the rotor in kgm2
If radial and/or axial acceleration occurs
during operation, the effect of the rigidityof the encoder bearing, the encoder stator
and the coupling are also significant. If suchloads occur in your application, HEIDENHAIN
recommends consulting with the main
office in Traunreut.
Conditions for longer storage periods
HEIDENHAIN recommends the following
in order to make storage periods beyond
12 months possible:• Leave the encoders in their original
packaging.
• The storage location should be dry, free of
dust, and temperature-regulated. It should
not be exposed to vibrations, mechanicalshock or chemical influences.
• Whenever encoders with an integral
bearing have been unused for 12 months,
rotate the shaft at low shaft speed andwithout axial or radial shaft loading sothat the bearing lubrication becomes
evenly redistributed (e.g., such as when
first breaking in an encoder).
Compensating currents
Compensating currents conducted throughthe encoder bearing may negatively affectthe functionality and are therefore notpermissible.

Parts subject to wear
Encoders from HEIDENHAIN are designed
for a long service life. Preventive maintenance is not required. However, they docontain components that are subject towear, depending on the application andhow they are deployed. These include inparticular the following parts:• LED light source• Cables with frequent flexing
For encoders with an integral bearing,
additionally:• Bearing• Shaft sealing rings for rotary encoders
and angle encoders• Sealing lips for sealed linear encoders

System tests
Encoders from HEIDENHAIN are usually
integrated as components into complete
systems. Applications of this type require
full-system, comprehensive testing,regardless of the encoder’s specifications.
The specifications provided in thisbrochure apply only to the encoder andnot to the entire system. Any operationof the encoder outside of the specified
range or outside of its proper and intended
use is solely at the user’s own risk.
Mounting
The steps and dimensions that must
be complied with during mounting
are specified solely in the mounting
instructions supplied with the device.
All mounting-related information in thisbrochure is therefore provisional andnon-binding; it does not become partof a contract.

Further information:
Please also comply with the following
planning and assembly documents:• Brochure: Cables and Connectors• Brochure: Interfaces of HEIDENHAIN
Encoders• Mounting Instructions of the encoder• Mounting Instructions for the adapter
cable

RoHS
HEIDENHAIN has tested its products toensure the use of non-hazardous materials
in accordance with the European Directives
2002/95/EC (RoHS) and 2002/96/EC (WEEE).
For a Manufacturer’s RoHS Declaration,please consult your sales agency.

37

RCN 2001 series

Shaft coupling with ring nut and catch (with mechanical fault exclusion) k 29.6

Newest generation of absolute angle encoders• System accuracies: ±2” and ±4”• Transmission of the direct-drive motor temperature• Integrated temperature sensor• Suitability for high shaft speeds• Hollow through shaft: ¬ 20 mm

11>9

Front-face shaft coupling (with mechanical fault exclusion) k>9Shaft coupling with ring nut(without mechanical fault exclusion) k
A = Bearing of mating shaft
d = Compressed air inlet
k = Required mating dimensions
1 = Mark for 0° position ±5°
2 = Cable support
3 = Customer-side free space
4 = Thread engagement: 4.5 mm ±0.5 mm (for M3 cylinder head screws; for details, see the mounting instructions)
5 = Accessory: ring nut (ID 336669-03)
6 = Accessory: catch (ID 817921-01)
7 = Thread engagement: 8 mm ±1 mm (for M4x20 cylinder head screws; for details, see the mounting instructions)
8 = Two spring pins: ISO 8752 – 2.5x10 – St
9 = If spring pins are used, then provide additional M3 back-off threads
10 = Direction of shaft rotation for ascending position values
11 = Stated tolerance includes mounting tolerances and thermal expansion; no dynamic movement permitted

Front-face shaft coupling(without mechanical fault exclusion) k



< 15



 29.6

>9

>9

38

39

Specifications

Absolute
RCN 2511

Measuring standard

DIADUR circular scale with absolute track and incremental track (16 384 lines)

System accuracy

±2”

±4”

Position error per signal period  ±0.3”

Absolute
RCN 2581
RCN 2381

Measuring standard

DIADUR circular scale with absolute track and incremental track (16 384 lines)

System accuracy

RCN 25x1: ±2”
RCN 23x1: ±4”

 ±0.4”

Functional safety
for applications with up to• SIL 2 as per EN 61508 (further basis for testing: EN 61800-5-2)• Category 3, PL d as per EN ISO 13849-1:2015

PFH

 25 · 10

Safe position1)

Encoder: ±0.22° (safety-related measuring step SM = 0.088°)
Mechanical coupling: fault exclusion for the loosening of the housing/flange and hollow shaft(see Functional safety and Mounting and accessories on Page 28/30)–9(up to 2000 m above sea level)

Interface

EnDat 2.2

Ordering designation

EnDat22

Positions/revolution

268 435 456 (28 bits)

Electrically permissible speed 3000 rpm for continuous position value

Clock frequency
Calculation time tcal

 16 MHz 5 µsPosition error per signal period RCN 2581:  ±0.4”
RCN 2381:  ±0.4”Electrical connection

Separate adapter cable connectable to encoder via quick connector

Cable length 100 m (with HEIDENHAIN cable; clock frequency  8 MHz)

Supply voltage

DC 3.6 V to 14 V

RCN 2591 F
RCN 2391 F

RCN 2591 M
RCN 2391 M

RCN 25x1:  ±0.3”
RCN 23x1:  ±0.4”

EnDat 2.2

Fanuc Serial Interface
1)
Þi interface

Mitsubishi high speed
interface

Panasonic SerialInterface

Ordering designation

EnDat02

Fanuc05

Mit03-4

Pana02

Position values/revolution1)

RCN 25x1: 268 435 456 (28 bits)
RCN 23x1: 67 108 864 (26 bits)

Electrically permissible speed

 1500 rpm forcontinuous position
values 3000 rpm for continuous position value

Clock frequency
Calculation time tcal

 2 MHz 8 µs–Incremental signals
Cutoff frequency –3 dB» 1 VPP 400 kHz–Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal
2)
motor temperature
converter (see Page 34)
Electrical connection
3)–

Separate adapter cable connectable to encoder via quick connector

Cable length 150 m 50 m 30 mSupply voltage

DC 3.6 V to 14 V

Power consumption4)(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Shaft

Hollow through shaft (¬ 20 mm)

Mech. permiss. shaft speed(at constant speed
for up to 90 min)

RCN 2x81:  1500 rpm
RCN 2x91:  3000 rpm (at an operating temperature of 40 °C;
for more details, see the permissible shaft speeds on Page 26)

Starting torque (at 20 °C)

Typically  0.08 Nm

Moment of inertia

Rotor (hollow shaft): 180 · 10–6 kgm2; stator (housing/flange): 670 · 10–6 kgm2

Power consumption(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Shaft

Hollow through shaft (¬ 20 mm)

Mech. permiss. shaft speed(at constant speed
for up to 90 min) 3000 rpm (at an operating temperature of 40 °C;
for details, see the permissible shaft speeds on Page 26)

Starting torque (at 20 °C)≤ 0.08 Nm (typical)

Moment of inertia

Rotor (hollow shaft): 180 · 10–6 kgm2
Stator (housing/flange): 670 · 10–6 kgm2

Permissible axial motionof measured shaft

Axial: ±0.3 mm4)
Radial: ¬ 0.2 mm for coaxially and, during operation, 0.04 mm for radial runout(each relative to the bearing axis of the mating shaft)

Permissible axial motionof measured shaft

Axial: ±0.3 mm5)
Radial: ¬ 0.2 mm coaxiliaty and 0.04 mm runout during operation(each relative to the bearing axis of the mating shaft)

Natural frequency

 1000 Hz

Natural frequency

 1000 Hz

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Operating temperature

0 °C to 60 °C

Operating temperature

0 °C to 60 °C

Protection EN 60529

IP64

Protection EN 60529

IP64

Mass

 1.1 kgMass

 1.1 kg

2

1)

1)

2)

2)

	Further tolerances may arise in the downstream electronics after position value comparison (contact mfr. of the downstream electronics)
	For detailed descriptions of the signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
See the General electrical information in the Interfaces of HEIDENHAIN Encoders brochure4)
Range includes mounting tolerances and thermal expansion; no dynamic movement permitted40

RCN 2591 P
RCN 2391 PInterface

67 108 864 (26 bits)

Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal converter (see Page 34)
2)
motor temperature

3)

Specifications
RCN 2311

2

Reduced resolution during operation for the Fanuc Þ interface; RCN 2591 F: 134 217 728 (27 bits); RCN 2391 F: 8 388 608 (23 bits)
	For detailed descriptions of the signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
With HEIDENHAIN cable  8 MHz
4)
See the General electrical information in the Interfaces of HEIDENHAIN Encoders brochure5)
Range includes mounting tolerances and thermal expansion; no dynamic movement permitted

41

RCN 5001 series
Newest generation of absolute angle encoders• System accuracies: ±2” and ±4”• Transmission of the direct-drive motor temperature• Integrated temperature sensor• Suitability for high shaft speeds• Hollow through shaft: ¬ 35 mm

Shaft coupling with ring nut and catch (with mechanical fault exclusion) k

 46

11

 84.9 ±0.03

 4.5/ 6

Front-face shaft coupling (with mechanical fault exclusion) k
11

Shaft coupling with ring nut(without mechanical fault exclusion) k
A = Bearing of mating shaft
d = Compressed air inlet
k = Required mating dimensions
1 = Mark for 0° position ±5°
2 = Cable support
3 = Customer-side free space
4 = Thread engagement: 4.5 mm ±0.5 mm (for M3 cylinder head screws; for details, see the mounting instructions)
5 = Accessory: ring nut (ID 336669-17)
6 = Accessory: catch (ID 817921-02)
7 = Thread engagement: 8 mm ±1 mm (for M4x20 cylinder head screws; for details, see the mounting instructions)
8 = Two spring pins: ISO 8752 – 2.5x10 – St
9 = If spring pins are used, then provide additional M3 back-off threads
10 = Direction of shaft rotation for ascending position values
11 = Stated tolerance includes mounting tolerances and thermal expansion; no dynamic movement permitted

Front-face shaft coupling(without mechanical fault exclusion) k


 30





42

43

Specifications

Absolute
RCN 5511

Measuring standard

DIADUR circular scale with absolute track and incremental track (16 384 lines)

System accuracy

±2”

±4”

Position error per signal period  ±0.3”• SIL 2 as per EN 61508 (further basis for testing: EN 61800-5-2)• Category 3, PL d as per EN ISO 13849-1:2015

PFH

 25 · 10

Safe position1)

Encoder: ±0.22° (safety-related measuring step SM = 0.088°)
Mechanical coupling: fault exclusion for the loosening of the housing/flange and hollow shaft(see Functional safety and Mounting and accessories on Page 28/30)–9(up to 2000 m above sea level)

Interface

EnDat 2.2

Ordering designation

EnDat22

Positions per revolution

268 435 456 (28 bits)

Electrically permissible speed 3000 rpm for continuous position value

Clock frequency
Calculation time tcal

 16 MHz 5 µsElectrical connection

Separate adapter cable connectable to encoder via quick connector

Cable length 100 m (with HEIDENHAIN cable; clock frequency  8 MHz)

Supply voltage

DC 3.6 V to 14 V

Power consumption(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Shaft

Hollow through shaft (¬ 35 mm)

Mech. permiss. shaft speed(at constant speed
for up to 90 min) 2000 rpm (at an operating temperature of 40 °C;
for more details, see the permissible shaft speeds on Page 26)

Starting torque (at 20 °C)≤ 0.2 Nm (typical)

Moment of inertia

Rotor (hollow shaft): 130 · 10–6 kgm2
Stator (housing/flange): 1010 · 10–6 kgm2
4)

Permissible axial motionof measured shaft

Axial: ±0.3 mm
Radial: ¬ 0.2 mm for coaxiality and, during operation, 0.04 mm for radial runout(each relative to the bearing axis of the mating shaft)

Natural frequency

 1000 Hz

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Operating temperature

0 °C to 60 °C

Protection EN 60529

IP64

Mass

 0.9 kg2

	Further tolerances may arise in the downstream electronics after position value comparison (contact mfr. of the downstream electronics)
	For detailed descriptions about signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
See the General electrical information in the Interfaces of HEIDENHAIN Encoders brochure4)
Range includes mounting tolerances and thermal expansion; no dynamic movement permitted
2)

44

Measuring standard

DIADUR circular scale with absolute track and incremental track (16 384 lines)

System accuracy

RCN 55x1: ±2”
RCN 53x1: ±4”

Position error per signal period RCN 5581:  ±0.4”
RCN 5381:  ±0.4”

RCN 5591 F
RCN 5391 F

RCN 5591 M
RCN 5391 M

RCN 5591 P
RCN 5391 P

RCN 55x1:  ±0.3”
RCN 53x1:  ±0.4”Interface

EnDat 2.2

Fanuc Serial Interface
1)
Þi interface

Mitsubishi high speed
interface

Panasonic SerialInterface

Ordering designation

EnDat02

Fanuc05

Mit03-4

Pana02

Positions per revolution1)

RCN 55x1: 268 435 456 (28 bits)
RCN 53x1: 67 108 864 (26 bits)

Electrically permissible speed

 1500 rpm forcontinuous position
values 3000 rpm for continuous position values

Clock frequency
Calculation time tcal

 2 MHz 8 µs–Incremental signals
Cutoff frequency –3 dB» 1 VPP 400 kHz–67 108 864 (26 bits)

Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal converter (see Page 34)
2)
motor temperature

1)

Absolute
RCN 5581
RCN 5381

 ±0.4”

Functional safety
for applications with up to

3)

Specifications
RCN 5311

Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal
2)
motor temperature
converter (see Page 34)
Electrical connection
3)–

Separate adapter cable connectable to encoder via quick connector

Cable length 150 m 50 m 30 mSupply voltage

DC 3.6 V to 14 V

Power consumption4)(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Shaft

Hollow through shaft (¬ 35 mm)

Mech. permiss. shaft speed(at constant speed
for up to 90 min)

RCN 5x81:  1500 rpm (operating temperature  50 °C)
 1200 rpm (operating temperature > 50 °C)
RCN 5x91:  2000 rpm (at an operating temperature of 40 °C;
for more details, see the permissible shaft speeds on Page 26)

Starting torque (at 20 °C)

Typically  0.2 Nm

Moment of inertia

Rotor (hollow shaft): 130 · 10–6 kgm2; stator (housing/flange): 1010 · 10–6 kgm2

Permissible axial motionof measured shaft

Axial: ±0.3 mm5)
Radial: ¬ 0.2 mm coaxiality and 0.04 mm runout during operation(each relative to the bearing axis of the mating shaft)

Natural frequency

 1000 Hz

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Operating temperature

0 °C to 60 °C

Protection EN 60529

IP64

Mass

 0.9 kg

2

1)

Reduced resolution during operation with the Fanuc Þ interface; RCN 5591 F: 134 217 728 (27 bits); RCN 5391 F: 8 388 608 (23 bits)
	For detailed descriptions about signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
With HEIDENHAIN cable  8 MHz
4)
See General electrical information in the Interfaces of HEIDENHAIN Encoders brochure5)
Range includes mounting tolerances and thermal expansion; no dynamic movement permitted
2)

45

RCN 8001 series
Newest generation of absolute angle encoders• System accuracies: ±1” and ±2”• Transmission of the direct-drive motor temperature• Integrated temperature sensor• Suitability for high shaft speeds• Hollow through shaft: ¬ 60 mm

Shaft coupling with ring nut and catch(with mechanical fault exclusion) k

Front-face shaft coupling(with mechanical fault exclusion) k

 70
12

12

(3

x)

 179.9±0.05

12

/ 6

 4.5

9





Front-face shaft coupling(without mechanical fault exclusion) k

9Shaft coupling with ring nut(without mechanical fault exclusion) k

36.2±0.9

A = Bearing of mating shaft
d = Compressed air inlet
k = Required mating dimensions
1 = Mark for 0° position ±5°
2 = Cable support
3 = Customer-side free space
4 = Shown rotated by 45°
5 = Thread engagement: 5.5 mm ±0.5 mm (for M4 cylinder head screws; for details, see the mounting instructions)
6 = Accessory: ring nut (ID 336669-11)
7 = Accessory: catch (ID 817921-03)
8 = Thread engagement: 11 mm ±1 mm (for M5x40 cylinder head screws; for details, see mounting instructions)
9 = Two spring pins: ISO 8752 – 4x10 – St
10 = Provide additional M4 back-off thread if spring pins are used
11 = Direction of shaft rotation for ascending position values
12 = Stated tolerance includes mounting tolerances and thermal expansion; no dynamic movement permitted



46

47

Specifications

Absolute
RCN 8511

Specifications

Absolute
RCN 8581
RCN 8381

Measuring standard

DIADUR circular scale with absolute track and incremental track (32 768 lines)

System accuracy

RCN 85x1: ±1”
RCN 83x1: ±2”

RCN 8311

Measuring standard

DIADUR circular scale with absolute track and incremental track (32 768 lines)

System accuracy

±1”

±2”

Position error per signal period  ±0.15”

 ±0.2”Functional safety
for applications with up to• SIL 2 as per EN 61508 (further basis for testing: EN 61800-5-2)• Category 3, PL d as per EN ISO 13849-1:2015

PFH

 25 · 10

Safe position1)

Encoder: ±0.11° (safety-related measuring step SM = 0.044°)
Mechanical coupling: fault exclusion for the loosening of the housing/flange and hollow shaft(see Functional safety and Mounting and accessories on Page 28/30)–9(up to 2000 m above sea level)

Position error per signal period RCN 8581:  ±0.2”
RCN 8381:  ±0.2”

RCN 8591 F
RCN 8391 F

RCN 8591 P
RCN 8391 P

RCN 85x1:  ±0.15”
RCN 83x1:  ±0.2”Interface

EnDat 2.2

Fanuc Serial Interface
1)
Þi interface

Mitsubishi high speed
interface

Panasonic SerialInterface

Ordering designation

EnDat02

Fanuc05

Mit03-4

Pana02

Position values/revolution1)

536 870 912 (29 bits)

Electrically permissible speed

 750 rpm forcontinuous position
values 1500 rpm for continuous position values

Interface

EnDat 2.2

Ordering designation

EnDat22

Positions per revolution

536 870 912 (29 bits)
 1500 rpm for continuous position values

Clock frequency
Calculation time tcal

 2 MHz 8 µs–Electrically permissible speed
Clock frequency
Calculation time tcal

 16 MHz 5 µsIncremental signals
Cutoff frequency –3 dB» 1 VPP 400 kHz–Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal converter (see Page 34)
2)
motor temperature

RCN 8591 M
RCN 8391 M

Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal
2)
motor temperature
converter (see Page 34)–

Separate adapter cable connectable to encoder via quick connector

Electrical connection

Separate adapter cable connectable to encoder via quick connector

Electrical connection

Cable length 100 m (with HEIDENHAIN cable; clock frequency  8 MHz)

Cable length 150 mSupply voltage

DC 3.6 V to 14 V

Supply voltage

DC 3.6 V to 14 V

Power consumption3)(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Power consumption4)(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Shaft

Hollow through shaft (¬ 60 mm)

Shaft

Hollow through shaft (¬ 60 mm)

Mech. permiss. shaft speed(at constant speed
for up to 90 min)

 1500 rpm (at an operating temperature of 40 °C;
for more details, see the permissible shaft speeds on Page 26)

Mech. permiss. shaft speed(at constant speed
for up to 90 min)

RCN 8x81:  750 rpm
RCN 8x91:  3000 rpm (at an operating temperature of 40 °C;
for more details, see the permissible shaft speeds on Page 26)

Starting torque (at 20 °C)≤ 0.7 Nm (typical)

Starting torque (at 20 °C)

Typically  0.7 Nm

Moment of inertia

Rotor (hollow shaft): 1.22 · 10–3 kgm2
Stator (housing/flange): 11 · 10–3 kgm2

Moment of inertia

Rotor (hollow shaft): 1.22 · 10–3 kgm2
Stator (housing/flange): 11 · 10–3 kgm2

Permissible axial motionof measured shaft

Axial: ±0.3 mm4)
Radial: ¬ 0.2 mm for coaxiality and, during operation, 0.04 mm for radial runout(each relative to the bearing axis of the mating shaft)

Permissible axial motionof measured shaft

Axial: ±0.3 mm5)
Radial: ¬ 0.2 mm coaxiality and 0.04 mm runout during operation(each relative to the bearing axis of the mating shaft)

Natural frequency

 900 Hz

Natural frequency

 900 Hz

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Operating temperature

0 °C to 50 °C

Operating temperature

0 °C to 50 °C

Protection EN 60529

IP64

Protection EN 60529

IP64

Mass

 2.8 kgMass

 2.8 kg

1)

2

	Further tolerances may arise in the downstream electronics after position value comparison (contact mfr. of the downstream electronics)
	For detailed descriptions about signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
See the General electrical information in the Interfaces of HEIDENHAIN Encoders brochure4)
Range includes mounting tolerances and thermal expansion; no dynamic movement permitted
2)

48

3)

 50 m 30 m2

1)

Reduced resolution during operation with the Fanuc Þ Interface; RCN 8x91 F: 134 217 728 (27 bits)
	For detailed descriptions about signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
With HEIDENHAIN cable  8 MHz
4)
See General electrical information in the Interfaces of HEIDENHAIN Encoders brochure5)
Range includes mounting tolerances and thermal expansion; no dynamic movement permitted
2)

49

RCN 8001 series
Newest generation of absolute angle encoders• System accuracies: ±1” and ±2”• Transmission of the direct-drive motor temperature• Integrated temperature sensor• Suitability for high shaft speeds• Hollow through shaft: ¬ 100 mm

Shaft coupling with ring nut and catch(with mechanical fault exclusion) k

Front-face shaft coupling(with mechanical fault exclusion) k

 9.5

 114

12

12

 179.9±0.05

12

/ 6

 4.5



50

Front-face shaft coupling(without mechanical fault exclusion) k 9.5

Shaft coupling with ring nut(without mechanical fault exclusion) k

36.2±0.9

A = Bearing of mating shaft
d = Compressed air inlet
k = Required mating dimensions
1 = Mark for 0° position ±5°
2 = Cable support
3 = Customer-side free space
4 = Thread engagement: 5.5 mm ±0.5 mm (for M4 cylinder head screws; for details, see the mounting instructions)
5 = Shown rotated by 45°
6 = Accessory: ring nut (ID 336669-16)
7 = Accessory: catch (ID 817921-04)
8 = Thread engagement: 11 mm ±1 mm (for M5 cylinder head screws; for details, see the mounting instructions)
9 = Two spring pins: ISO 8752 – 4x10 – St
10 = Provide additional M4 back-off thread if spring pins are used
11 = Direction of shaft rotation for ascending position values
12 = Stated tolerance includes mounting tolerances and thermal expansion; no dynamic movement permitted

51

Specifications

Absolute
RCN 8511

Specifications

Absolute
RCN 8581
RCN 8381

Measuring standard

DIADUR circular scale with absolute track and incremental track (32 768 lines)

System accuracy

RCN 85x1: ±1”
RCN 83x1: ±2”

RCN 8311

Measuring standard

DIADUR circular scale with absolute track and incremental track (32 768 lines)

System accuracy

±1”

±2”

Position error per signal period  ±0.15”

 ±0.2”Functional safety
for applications with up to• SIL 2 as per EN 61508 (further basis for testing: EN 61800-5-2)• Category 3, PL d as per EN ISO 13849-1:2015

PFH

 25 · 10

Safe position1)

Encoder: ±0.11° (safety-related measuring step SM = 0.044°)
Mechanical coupling: fault exclusion for the loosening of the housing/flange and hollow shaft(see Functional safety and Mounting and accessories on Page 28/30)–9(up to 2000 m above sea level)

Position error per signal period RCN 8581:  ±0.2”
RCN 8381:  ±0.2”

RCN 8591 F
RCN 8391 F

RCN 8591 P
RCN 8391 P

RCN 85x1:  ±0.15”
RCN 83x1:  ±0.2”Interface

EnDat 2.2

Fanuc Serial Interface
1)
Þi interface

Mitsubishi high speed
interface

Panasonic SerialInterface

Ordering designation

EnDat02

Fanuc05

Mit03-4

Pana02

Position values/revolution1)

536 870 912 (29 bits)

Electrically permissible speed

 750 rpm forcontinuous position
values 1500 rpm for continuous position values

Interface

EnDat 2.2

Ordering designation

EnDat22

Positions per revolution

536 870 912 (29 bits)
 1500 rpm for continuous position values

Clock frequency
Calculation time tcal

 2 MHz 8 µs–Electrically permissible speed
Clock frequency
Calculation time tcal

 16 MHz 5 µsIncremental signals
Cutoff frequency –3 dB» 1 VPP 400 kHz–Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal converter (see Page 34)
2)
motor temperature

RCN 8591 M
RCN 8391 M

Measurement of direct-drive Possible with the HEIDENHAIN EIB 5000 signal
2)
motor temperature
converter (see Page 34)–

Separate adapter cable connectable to encoder via quick connector

Electrical connection

Separate adapter cable connectable to encoder via quick connector

Electrical connection

Cable length 100 m (with HEIDENHAIN cable; clock frequency  8 MHz)

Cable length 150 mSupply voltage

DC 3.6 V to 14 V

Supply voltage

DC 3.6 V to 14 V

Power consumption3)(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Power consumption4)(maximum)3.6 V:  1.1 W
14 V:  1.3 W

Shaft

Hollow through shaft (¬ 100 mm)

Shaft

Hollow through shaft (¬ 100 mm)

Mech. permiss. shaft speed(at constant speed
for up to 90 min) 1200 rpm (at an operating temperature of 40 °C;
for details, see the permissible shaft speeds on Page 26)

Mech. permiss. shaft speed(at constant speed
for up to 90 min)

RCN 8x81:  750 rpm
RCN 8x91:  1200 rpm (at an operating temperature of 40 °C;
for details, see the permissible shaft speeds on Page 26)

Starting torque (at 20 °C)≤ 1.0 Nm (typical)

Starting torque (at 20 °C)

Typically  1.0 Nm

Moment of inertia

Rotor (hollow shaft): 3.2 · 10–3 kgm2
Stator (housing/flange): 10 · 10–3 kgm2

Moment of inertia

Rotor (hollow shaft): 3.2 · 10–3 kgm2
Stator (housing/flange): 10 · 10–3 kgm2

Permissible axial motionof measured shaft

Axial: ±0.3 mm4)
Radial: ¬ 0.2 mm for coaxiality and, during operation, 0.04 mm for radial runout(each relative to the bearing axis of the mating shaft)

Permissible axial motionof measured shaft

Axial: ±0.3 mm5)
Radial: ¬ 0.2 mm coaxiality and 0.04 mm runout during operation(each relative to the bearing axis of the mating shaft)

Natural frequency

 900 Hz

Natural frequency

 900 Hz

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Vibration 55 Hz to 2000 Hz
Shock 6 ms

 200 m/s (EN 60068-2-6)
 200 m/s2 (EN 60068-2-27)

Operating temperature

0 °C to 50 °C

Operating temperature

0 °C to 50 °C

Protection EN 60529

IP64

Protection EN 60529

IP64

Mass

 2.6 kgMass

 2.6 kg

2

3)

1)

1)

2)

2)

	Further tolerances may arise in the downstream electronics after position value comparison (contact mfr. of the downstream electronics)
	For detailed descriptions about signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
See the General electrical information in the Interfaces of HEIDENHAIN Encoders brochure4)
Range includes mounting tolerances and thermal expansion; no dynamic movement permitted52

 50 m 30 m2

Reduced resolution during operation with Fanuc Þ Interface; RCN 8x91 F: 134 217 728 (27 bits)
	For detailed descriptions about signal converters for measuring the temperature of direct-drive motors, see the EIB 5000 Product
Information document
3)
With HEIDENHAIN cable  8 MHz
4)
See General electrical information in the Interfaces of HEIDENHAIN Encoders brochure5)	Range includes mounting tolerances and thermal expansion; no dynamic movement permitted

53

Testing and inspection devices, and diagnostics

HEIDENHAIN encoders provide all of theinformation needed for initial setup,monitoring, and diagnostics. The type ofavailable information depends on whether
it is an absolute or incremental encoderand on which interface is used.
Absolute encoders use serial datatransmission. Depending on the interface,
additional 1 VPP incremental signals can be
output. The signals are extensively monitored
within the encoder. The monitoring results(particularly valuation numbers) can betransmitted to the downstream electronics
along with the position values via the serialinterface (digital diagnostics interface).
The following information is available:• Error message: position value is notreliable• Warning: an internal functional limit of
the encoder has been reached• Valuation numbers:– Detailed information on the encoder’sfunction reserve– Identical scaling for all HEIDENHAIN
encoders– Cyclic reading is possible
This enables the downstream electronics
to evaluate the current status of theencoder with little effort, even in closed
loop mode.

PWT 101
The PWT 101 is a testing device for thefunctional testing and adjustment of
incremental and absolute HEIDENHAIN
encoders. Thanks to its compact andrugged design, the PWT 101 is ideal for
portable use.

Diagnostics with the PWM 21 and ATS software

Encoder input
only for HEIDENHAIN
encoders• EnDat• Fanuc Serial Interface• Mitsubishi high speed interface• Panasonic Serial Interface• Yaskawa Serial Interface• 1 VPP• 11 µAPP• TTL

Display

4.3-inch color flat-panel display (touchscreen)

Supply voltage

DC 24 VPower consumption: max. 15 W

Operating temperature

0 °C to 40 °C

Protection EN 60529

IP20

Dimensions

 145 mm × 85 mm × 35 mm

Further information:
For a detailed description, refer to the
PWT 101 Product Information document.

PWM 21The PWM 21 phase-angle measuring unit,
in conjunction with the included ATS
adjusting and testing software, serves as
an adjusting and testing package for the
diagnosis and adjustment of HEIDENHAIN
encoders.

Incremental encoders have 1 VPP, TTL, or
HTL interfaces. TTL and HTL encoders
monitor their signal amplitudes internally andgenerate a simple fault detection signal.
With 1 VPP signals, an analysis of the output
signals is possible only with external testing
devices or through the use of computation
resources in the downstream electronics(analog diagnostics interface).
For the analysis of these encoders,
HEIDENHAIN offers the appropriate PWM
inspection devices and PWT testing devices.
Based on how these devices are integrated,a distinction is made between two typesof diagnostics:• Encoder diagnostics: the encoder isconnected directly to the testing or
inspection device, thereby enabling adetailed analysis of encoder functions.
• Monitoring mode: the PWM inspection
device is inserted within the closed
control loop (via suitable testing adapters
as needed). This enables real-time
diagnosis of the machine or equipment
during operation. The available functions
depend on the interface.

PWT 101

PWM 21
Encoder input• EnDat 2.1, EnDat 2.2, or EnDat 3 (absolute value withor without incremental signals)• DRIVE-CLiQ• Fanuc Serial Interface• Mitsubishi high speed interface• Yaskawa Serial Interface• Panasonic serial interface• SSI• 1 VPP/TTL/11 µAPP
• HTL (via signal adapter)

InterfaceUSB 2.0

Supply voltage

AC 100 V to 240 V or DC 24 V

Dimensions

258 mm × 154 mm × 55 mm

Initial setup with the PWM 21 and ATS softwareATS
Languages

German or English (selectable)

Functions• Position display• Connection dialog• Diagnostics• Mounting wizard for EBI/ECI/EQI, LIP 200, LIC 4000
and others• Additional functions (if supported by the encoder)• Memory contents

System requirements
and recommendations

PC (dual-core processor > 2 GHz)
RAM > 2 GB
Operating systems: Windows 7, 8, and 10 (32-bit / 64-bit)
500 MB of free hard drive space

Further information:
For detailed descriptions about
diagnostics, and inspection devices andtesting devices, please refer to theInterfaces of HEIDENHAIN Encoders
brochure (ID 1078628-xx).

54

Further information:
For detailed descriptions, refer tothe PWM 21/ATS Software Product
Information document.

DRIVE-CLiQ is a registered trademark of Siemens Aktiengesellschaft.

55

Mastering nanometer accuracy

DR. JOHANNES HEIDENHAIN GmbH
Dr.-Johannes-Heidenhain-Straße 583301 Traunreut, Germany +49 8669 31-0
 +49 8669 32-5061
info@heidenhain.dewww.heidenhain.com
591109-25 · 1 · 08/2022 · H · Printed in Germany

HEIDENHAIN
worldwide