HEIDENHAIN Interfaces Service Manual

July 2013

Interfaces

of HEIDENHAIN Encoders

Interfaces

As deﬁned transitions between encoders and subsequent electronics, interfaces ensure the reliable exchange of information.

HEIDENHAIN offers encoders with interfaces for many common subsequent electronics. The interface possible in each respective case depends, among other things, on the measuring method used by the encoder.

Measuring methods

In the incremental measuring method the position information is obtained by counting the individual increments (measuring steps) from some point of origin. Since an absolute reference is necessary in order to determine the positions, a reference-mark signal is output as well. As a general rule, encoders that operate with the incremental measuring method output incremental signals. Some incremental encoders with integrated interface electronics also have a counting function: Once the reference mark is traversed, an absolute position value is formed and output via a serial interface.

Note

Specialized encoders can have other interface properties, such as regarding the shielding.

With the absolute measuring method the absolute position information is gained directly from the graduation of the measuring standard. The position value is available from the encoder immediately upon switch-on and can be called at any time by the subsequent electronics.

Encoders that operate with the absolute measuring method output position values. Some interfaces provide incremental signals as well.

Absolute encoders do not require a reference run, which is advantageous particularly in concatenated manufacturing systems, transfer lines, or machines with numerous axes. Also, they are more resistant to EMC interferences.

Interface electronics

Interface electronics from HEIDENHAIN adapt the encoder signals to the interface of the subsequent electronics. They are used when the subsequent electronics cannot directly process the output signals from HEIDENHAIN encoders, or if additional interpolation of the signals is necessary.

You can ﬁnd more detailed information in the Interface Electronics Product Overview.

This catalog supersedes all previous editions, which thereby become invalid. The basis for ordering from HEIDENHAIN is always the catalog edition valid when the contract is made.

Contents

Incremental signals

Position values

Sinusoidal signals 1 V

Square-wave signals TTL

Serial interfaces EnDat

11 µA

HTL

HTLs

Siemens

Fanuc

Mitsubishi

PROFIBUS-DP

PROFINET IO

Voltage signals, can be highly interpolated

Current signals, can be interpolated

RS 422, typically 5 V

Typically 10 V to 30 V

Typically 10 V to 30 V, without inverted signals

Bidirectional interface With incremental signals

Without incremental signals

Company-speciﬁc information Without incremental signals

Fieldbus Without incremental signals

Ethernet-based ﬁeldbus Without incremental signals

Other signals

Further information

SSI

Limit/Homing Limit switches

Position detection

Commutation signals Block commutation

Sinusoidal commutation

Overview of interface electronics

HEIDENHAIN testing equipment

General electrical information

Synchronous serial interface With incremental signals

With incremental signals

Incremental signals

» 1 VPP sinusoidal signals

HEIDENHAIN encoders with » 1 VPP interface provide voltage signals that can be highly interpolated.

The sinusoidal incremental signals A and B are phase-shifted by 90° elec. and have an amplitude of typically 1 V

. The illustrated sequence of output signals— with B lagging A—applies for the direction of motion shown in the dimension drawing.

The reference mark signal R has a usable component G of approx. 0.5 V. Next to the reference mark, the output signal can be reduced by up to 1.7 V to a quiescent level H. This must not cause the subsequent electronics to overdrive. Even at the lowered signal level, signal peaks with the amplitude G can also appear.

The data on signal amplitude apply when the supply voltage given in the speciﬁcations is connected to the encoder. They refer to a differential measurement at the 120 ohm terminating resistor between the associated outputs. The signal amplitude decreases with increasing frequency. The cutoff frequency indicates the scanning frequency at which a certain percentage of the original signal amplitude is maintained:

–3 dB •  70 % of the signal amplitude –6 dB •  50 % of the signal amplitude

Interface

Incremental signals

Sinusoidal voltage signals » 1 V

Two nearly sinusoidal signals A and B

Signal amplitude M: 0.6 to 1.2 V

; typically 1 V

Asymmetry |P – N|/2M:  0.065 Amplitude ratio M

: 0.8 to 1.25

A/MB

Phase angle |j1 + j2|/2: 90° ± 10° elec.

Reference mark signal

One or several signal peaks R

Usable component G:  0.2 V Quiescent value H:  1.7 V Switching threshold E, F: 0.04 V to 0.68 V Zero crossovers K, L: 180° ± 90° elec.

Connecting cable

Cable length Propagation time

Shielded HEIDENHAIN cable For example PUR [4(2 x 0.14 mm

) + (4 x 0.5 mm2)] Max. 150 m at 90 pF/m distributed capacitance 6 ns/m

These values can be used for dimensioning of the subsequent electronics. Any limited tolerances in the encoders are listed in the speciﬁcations. For encoders without integral bearing, reduced tolerances are recommended for initial operation (see the mounting instructions).

Signal period

360° elec.

The data in the signal description apply to motions at up to 20 % of the –3 dB cutoff frequency.

Interpolation/resolution/measuring step

The output signals of the 1 V

interface

are usually interpolated in the subsequent electronics in order to attain sufﬁciently high resolutions. For velocity control, interpolation factors are commonly over 1000 in order to receive usable information even at low rotational or linear velocities.

Measuring steps for position measurement are recommended in the speciﬁcations. For special applications, other resolutions are also possible.

Short-circuit stability

A temporary short circuit of one signal output to 0 V or U U

= 3.6 V) does not cause encoder

Pmin

(except encoders with

failure, but it is not a permissible operating condition.

Short circuit at 20 °C 125 °C

One output < 3 min < 1 min

All outputs < 20 s < 5 s

A, B, R measured with oscilloscope in differential mode

Cutoff frequency

Typical signal amplitude curve with respect to the scanning frequency (depends on encoder)

(rated value)



Signal amplitude [%]

–3 dB cutoff frequency –6 dB cutoff frequency

Alternative signal shape

Scanning frequency [kHz]



Monitoring of the incremental signals

The following sensitivity levels are recommended for monitoring the signal amplitude M: Lower threshold: 0.30 V Upper threshold: 1.35 V

The height of the incremental signals can be monitored, for example by the length of the resulting position indicator: The oscilloscope shows the output signals A and B as a Lissajous ﬁgure in the XY graph. Ideal sinusoidal signals produce a circle with the diameter M. In this case the position indicator r shown corresponds to ½M. The formula is therefore

2+B2

r =

(A

)

with the condition 0.3 V < 2r < 1.35 V.

Input circuitry of subsequent electronics

Dimensioning

Operational ampliﬁer, e.g. MC 34074 Z

= 120 

= 10 k and C1 = 100 pF

= 34.8 k and C2 = 10 pF

= ±15 V

approx. U

–3 dB cutoff frequency of circuitry

Approx. 450 kHz Approx. 50 kHz with C and C The circuit variant for 50 kHz does reduce the bandwidth of the circuit, but in doing so it improves its noise immunity.

= 1000 pF

= 82 pF

Incremental signals Reference mark signal

Ra < 100 , typically 24  Ca < 50 pF SIa < 1 mA U0 = 2.5 V ± 0.5 V (relative to 0 V of the supply voltage)

Incremental signal A

Time [t]

Encoder Subsequent electronics



Incremental signal B



Time [t]

Circuit output signals

= 3.48 VPP typically

Gain 3.48

Input circuitry of subsequent electronics for high signal frequencies

For encoders with high signal frequencies (e.g. LIP 281), a special input circuitry is required.

Dimensioning

Operational ampliﬁer, e.g. AD 8138 Z

= 120 

= 681 ; R2 = 1 k; R3 = 464 

= 15 pF; C1 = 10 pF

= 5 V; –UB = 0 V or –5 V

–3 dB cutoff frequency of circuitry

Approx. 10 MHz

Circuit output signals

= 1.47 VPP typically

Gain 1.47

Incremental signals Reference mark signal

Ra < 100 , typically 24  Ca < 50 pF SIa < 1 mA U0 = 2.5 V ± 0.5 V (relative to 0 V of the supply voltage)

LIP 281 encoder Subsequent electronics

Incremental signals

» 11 µAPP sinusoidal signals

HEIDENHAIN encoders with » 11 µAPP interface provide current signals. They are intended for connection to ND position display units or EXE pulse-shaping electronics from HEIDENHAIN.

The sinusoidal incremental signals I and I

are phase-shifted by 90° elec. and

have signal levels of approx. 11 µA

. The illustrated sequence of output signals—with I

lagging I1—applies to

the direction of motion shown in the dimension drawing, and for retracting plungers of length gauges.

The reference mark signal I

has a usable

component G of approx. 5.5 µA.

The data on signal amplitude apply when the supply voltage given in the Speciﬁcations is connected at the encoder. They refer to a differential measurement between the associated outputs. The signal amplitude decreases with increasing frequency. The cutoff frequency indicates the scanning frequency at which a certain percentage of the original signal amplitude is maintained:

–3 dB cutoff frequency: • 70 % of the signal amplitude –6 dB cutoff frequency: • 50 % of the signal amplitude

Interface

Sinusoidal current signals » 11 µA

Incremental signals Two nearly sinusoidal signals I1 and I

Signal amplitude M: 7 to 16 µAPP/typically 11 µA Asymmetry IP – NI/2M:  0.065 Amplitude ratio M

: 0.8 to 1.25

A/MB

Phase angle |j1 + j2|/2: 90° ± 10° elec.

Reference mark signal

One or more signal peaks I

Usable component G: 2 µA to 8.5 µA Switching threshold E, F:  0.4 µA Zero crossovers K, L: 180° ± 90° elec.

Connecting cable

Cable length Propagation time

Shielded HEIDENHAIN cable PUR [3(2 · 0.14 mm

) + (2 · 1 mm2)] Max. 30 m with 90 pF/m distributed capacitance 6 ns/m

Signal period

360° elec.

Interpolation/resolution/measuring step

The output signals of the 11 µA

interface are usually interpolated in the subsequent electronics—ND position displays or EXE pulse-shaping electronics from HEIDENHAIN— in order to attain sufﬁciently high resolutions.

(rated value)

 TTL square-wave signals

HEIDENHAIN encoders with  TTL interface incorporate electronics that digitize sinusoidal scanning signals with or without interpolation.

The incremental signals are transmitted as the square-wave pulse trains U U

, phase-shifted by 90° elec. The

and

reference mark signal consists of one or more reference pulses U

, which are

gated with the incremental signals. In addition, the integrated electronics produce their inverted signals ¢, £ and ¤ for noise-proof transmission. The illustrated sequence of output signals—with U lagging U

—applies to the direction of

motion shown in the dimension drawing.

The fault-detection signal ¥ indicates fault conditions such as breakage of the power line or failure of the light source. It can be used for such purposes as machine shut-off during automated production.

The distance between two successive edges of the incremental signals U U

through 1-fold, 2-fold or 4-fold

and

evaluation is one measuring step.

The subsequent electronics must be designed to detect each edge of the square-wave pulse. The minimum edge separation a stated in the Speciﬁcations applies for the speciﬁed input circuit with a cable length of 1 m and refers to a measurement at the output of the differential line receiver.

Interface

Incremental signals

Reference mark signal

Pulse width Delay time

Fault-detection signal

Pulse width

Signal amplitude

Permissible load

Switching times

(10 % to 90 %)

Connecting cable

Cable length Propagation time

Square-wave signals « T T L

Two TTL square-wave signals U

, Ua2 and their inverted

signals ¢, £

One or more TTL square-wave pulses U

and their inverted

pulses ¤ 90° elec. (other widths available on request) |t

|  50 ns

One TTL square-wave pulse ¥

Improper function: LOW (upon request: U

high impedance)

a1/Ua2

Proper function: HIGH t

 20 ms

Differential line driver as per EIA standard RS-422

 100  Between associated outputs

|  20 mA Max. load per output (ERN 1x23: 10 mA)

 1000 pF With respect to 0 V

load

Outputs protected against short circuit to 0 V

/ t–  30 ns (typically 10 ns)

with 1 m cable and recommended input circuitry

Shielded HEIDENHAIN cable For example PUR [4(2 × 0.14 mm

) + (4 × 0.5 mm2)] Max. 100 m (¥ max. 50 m) at distributed capacitance 90 pF/m Typically 6 ns/m

Signal period 360° elec.

Fault

Note

Not all encoders output a reference mark signal, fault-detection signal, or their inverted signals. Please see the connector layout for this.

Measuring step after 4-fold evaluation

Inverse signals ¢, £, ¤ are not shown

Clocked output signals are typical for

encoders and interpolation electronics with 5-fold interpolation (or greater). They derive the edge separation a from an internal clock source. At the same time, the clock frequency determines the permissible input frequency of the incremental signals (1 V

or 11 µAPP) and the resulting

maximum permissible traversing velocity or shaft speed:

nom

nominal edge separation

nom

4 · IPF · fe

nom

IPF interpolation factor fe

nominal input frequency

nom

The tolerances of the internal clock source have an inﬂuence on the edge separation a of the output signal and the input frequency f

, thereby inﬂuencing the

traversing velocity or shaft speed.

The data for edge separation already takes these tolerances into account with 5 %: Not the nominal edge separation is indicated, but rather the minimum edge separation a

min

On the other hand, the maximum permissible input frequency must consider a tolerance of at least 5 %. This means that the maximum permissible traversing velocity or shaft speed are also reduced accordingly.

Encoders and interpolation electronics without interpolation in general do not have clocked output signals. The minimum edge separation a

that occurs at the

min

maximum possible input frequency is stated in the speciﬁcations. If the input frequency is reduced, the edge separation increases correspondingly.

Cable-dependent differences in the propagation time additionally reduce the

edge separation by 0.2 ns per meter of cable. To prevent counting errors, a safety margin of 10 % must be considered, and the subsequent electronics so designed that they can process as little as 90 % of the resulting edge separation.

Please note: The max. permissible shaft speed or traversing velocity must never be

exceeded, since this would result in an irreversible counting error.

Calculation example 1

LIDA 400 linear encoder Requirements: display step 0.5 µm, traversing velocity 1 m/s, output signals TTL, cable length to subsequent electronics 25 m. What minimum edge separation must the subsequent electronics be able to process?

Selection of the interpolation factor

20 µm grating period : 0.5 µm display step = 40-fold subdivision Evaluation in the subsequent electronics 4-fold

Interpolation 10-fold Selection of the edge separation

Traversing velocity 60 m/min (corresponds to 1 m/s) + tolerance value 5 % 63 m/min

Select in speciﬁcations:

Next LIDA 400 version 120 m/min (from speciﬁcations)

Minimum edge separation 0.22 µs (from speciﬁcations) Determining the edge separation that the subsequent electronics must process

Subtract cable-dependent differences in the propagation time 0.2 ns per meter For cable length = 25 m 5 ns Resulting edge separation 0.215 µs Subtract 10 % safety margin 0.022 µs

Minimum edge separation for the subsequent electronics 0.193 µs

Calculation example 2

ERA 4000 angle encoder with 32 768 lines Requirements: measuring step 0.1”, output signals TTL (IBV external interface electronics necessary), cable length from IBV to subsequent electronics = 20 m, minimum edge separation that the subsequent electronics can process = 0.5 µs (input frequency = 2 MHz). What rotational speed is possible?

Selection of the interpolation factor

32 768 lines corresponds to 40” signal period Signal period 40” : measuring step 0.1” = 400-fold subdivision Evaluation in the subsequent electronics 4-fold

Interpolation in the IBV 100-fold Calculation of the edge separation

Permissible edge separation of the subsequent electronics 0.5 µs

This corresponds to 90 % of the resulting edge separation

This leads to: Resulting edge separation 0.556 µs Subtract cable-dependent differences in the propagation time 0.2 ns per meter For cable length = 20 m 4 ns

Minimum edge separation of IBV 102  0.56 µs Selecting the input frequency

According to the Product Information, the input frequencies and therefore the edge separations a of the IBV 102 can be set.

Next suitable edge separation 0.585 µs

Input frequency at 100-fold interpolation 4 kHz Calculating the permissible shaft speed

Subtract 5 % tolerance 3.8 kHz This is 3 800 signals per second or 228 000 signals per minute. Meaning for 32 768 lines of the ERA 4000:

Max. permissible rotational speed 6.95 rpm

The permissible cable length for transmission of the TTL square-wave signals to the subsequent electronics depends on the edge separation a. It is at most 100 m, or 50 m for the fault detection signal. This requires, however, that the voltage supply (see Speciﬁcations) be ensured at the encoder. The sensor lines can be used to measure the voltage at the encoder and, if required, correct it with an automatic control system (remote sense voltage supply).

Greater cable lengths can be provided upon consultation with HEIDENHAIN.

Permissible cable length

with respect to the edge separation



Cable length [m]

Without ¥

With ¥

Edge separation [µs]



Input circuitry of subsequent electronics

Dimensioning

= Recommended differential line

receiver DS 26 C 32 AT Only for a > 0.1 µs: AM 26 LS 32 MC 3486 SN 75 ALS 193

= 4.7 k

= 1.8 k

= 120 

= 220 pF (serves to improve noise

immunity)

Incremental signals Reference mark signal

Fault-detection signal

Encoder Subsequent electronics

HTLsHTL

Incremental signals

 HTL square-wave signals

HEIDENHAIN encoders with  HTL interface incorporate electronics that digitize sinusoidal scanning signals with or without interpolation.

The incremental signals are transmitted as the square-wave pulse trains U

and Ua2,

phase-shifted by 90° elec. The reference mark signal consists of one or more reference pulses U

, which are gated with

the incremental signals. In addition, the integrated electronics produce their inverted signals ¢, £ and ¤ for noise-proof transmission (does not apply to HTLs).

The illustrated sequence of output signals—with U

lagging Ua1—applies to

the direction of motion shown in the dimension drawing.

The fault-detection signal ¥ indicates fault conditions such as failure of the light source. It can be used for such purposes as machine shut-off during automated production.

The distance between two successive edges of the incremental signals U U

through 1-fold, 2-fold or 4-fold

and

evaluation is one measuring step.

The subsequent electronics must be designed to detect each edge of the square-wave pulse. The minimum edge separation a listed in the Speciﬁcations refers to a measurement at the output of the given differential input circuitry. To prevent counting errors, the subsequent electronics should be designed so that they can process as little as 90% of the edge separation a. The maximum permissible shaft speed or traversing velocity must never be exceeded.

Interface

Incremental signals

Reference mark signal

Pulse width Delay time

Fault-detection signal

Pulse width

Signal levels

Permissible load

Switching times

(10 % to 90 %)

Connecting cable

Cable length

Propagation time

Signal period 360° elec.

Square-wave signals « HTL, « HTLs

Two HTL square-wave signals U

, Ua2 and their inverted

signals ¢, £ (HTLs without ¢, £)

One or more HTL square-wave pulses U

and their

inverted pulses ¤ (HTLs without ¤) 90° elec. (other widths available on request) |t

|  50 ns

One HTL square-wave pulse ¥

Improper function: LOW Proper function: HIGH

 20 ms

 21 V at –IH = 20 mA With voltage supply of

 2.8 V at IL = 20 mA UP = 24 V, without cable

|  100 mA Max. load per output, (except ¥)

 10 nF With respect to 0 V

load

Outputs short-circuit proof for max. 1 minute to 0 V and U (except ¥)

 200 ns (except ¥)

+/t–

with 1 m cable and recommended input circuitry

HEIDENHAIN cable with shielding e. g. PUR [4(2 × 0.14 mm

) + (4 × 0.5 mm2)] Max. 300 m (HTLs max. 100 m) at distributed capacitance 90 pF/m 6 ns/m

Fault

Measuring step after 4-fold evaluation

The permissible cable length for incremental encoders with HTL signals depends on the scanning frequency, the effective supply voltage, and the operating temperature of the encoder.

The current requirement of encoders with HTL output signals depends on the output frequency and the cable length to the subsequent electronics.



Cable length [m]

Inverse signals ¢, £, ¤ are not shown

Scanning frequency [kHz]



Input circuitry of subsequent electronics HTL

Incremental signals Reference mark signal

Fault-detection signal

Encoder Subsequent electronics

HTLs

Incremental signals Reference mark signal

Fault-detection signal

Encoder Subsequent electronics

Position values

serial interface

The EnDat interface is a digital, bidirectional interface for encoders. It is capable both of transmitting position values as well as transmitting or updating information stored in the encoder, or saving new information. Thanks to the serial transmission method, only four signal lines are required. The data is transmitted in synchronism with the clock signal from the subsequent electronics. The type of transmission (position values, parameters, diagnostics, etc.) is selected through mode commands that the subsequent electronics send to the encoder. Some functions are available only with EnDat 2.2 mode commands.

History and compatibility

The EnDat 2.1 interface available since the mid-90s has since been upgraded to the EnDat 2.2 version (recommended for new applications). EnDat 2.2 is compatible in its communication, command set and time conditions with version 2.1, but also offers signiﬁcant advantages. It makes it possible, for example, to transfer additional data (e.g. sensor values, diagnostics, etc.) with the position value without sending a separate request for it. This permits support of additional encoder types (e.g. with battery buffer, incremental encoders, etc.). The interface protocol was expanded and the time conditions (clock frequency, processing time, recovery time) were optimized.

Supported encoder types

The following encoder types are currently supported by the EnDat 2.2 interface (this information can be read out from the encoder’s memory area):

Incremental linear encoder• Absolute linear encoder• Rotational incremental singleturn • encoder Rotational absolute singleturn encoder• Multiturn rotary encoder• Multiturn rotary encoder with battery •

buffer In some cases, parameters must be interpreted differently for the various encoder types (see EnDat Speciﬁcations) or EnDat additional data must be processed (e.g. incremental or batterybuffered encoders).

Interface

Data transfer

Data input Differential line receiver according to EIA standard RS 485 for the

Data output Differential line driver according to EIA standard RS 485 for the

Position values Ascending during traverse in direction of arrow (see dimensions

Incremental signals

Order designations

The order designations deﬁne the central speciﬁcations and give information about:

Typical power supply range• Command set• Availability of incremental signals•

Maximum clock frequency• The second character of the order designation identiﬁes the interface generation. For encoders of the current generation the order designation can be read out from the encoder memory.

Incremental signals

Some encoders also provide incremental signals. These are usually used to increase the resolution of the position value, or to serve a second subsequent electronics unit. Current generations of encoders have a high internal resolution, and therefore no longer need to provide incremental signals. The order designation indicates whether an encoder outputs incremental signals:

EnDat 01 with 1 V•

EnDat Hx with HTL incremental signals•

EnDat Tx with TTL incremental signals•

EnDat 21 without incremental signals•

EnDat 02 with 1 V•

EnDat 22 without incremental signals•

Notes on EnDat 01, 02:

The signal period is stored in the encoder memory

Notes on EnDat Hx, Tx:

The encoder-internal subdivision of the incremental signal is indicated by the order designation: Ha, Ta: 2-fold interpolation Hb, Tb: No interpolation Hc: Scanning signals x 2

EnDat serial bidirectional

Position values, parameters and additional data

signals CLOCK, CLOCK

signals DATA and DATA

of the encoders)

Depends on encoder » 1 V

incremental signals

, TTL, HTL (see the respective Incremental signals)

, DATA and DATA

Voltage supply

The typical voltage supply of the encoders depends on the interface:

EnDat 01 EnDat 21

EnDat 02 EnDat 22

EnDat Hx 10 V to 30 V

EnDat Tx 4.75 V to 30 V

Exceptions are documented in the Speciﬁcations.

Command set

The command set describes the available mode commands, which deﬁne the exchange of information between the encoder and the subsequent electronics. The EnDat 2.2 command set includes all EnDat 2.1 mode commands. In addition, EnDat 2.2 permits further mode commands for the selection of additional data, and makes memory accesses possible even in a closed control loop. When a mode command from the EnDat 2.2 command set is transmitted to an encoder that only supports the EnDat 2.1 command set, an error message is generated. The supported command set is stored in the encoder’s memory area:

EnDat 01, 21, Hx, Tx Command set •

EnDat 02, 22 Command set •

5 V ± 0.25 V

3.6 V to 5.25 V or 14 V

2.1 or 2.2

2.2

For more information, refer to the EnDat Technical Information sheet or visit www.endat.de.

+ 28 hidden pages

HEIDENHAIN Interfaces Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual