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SINUMERIK 840D sl. Service - Functions. Manual (2018-2020) - page 4

Introduction

1

1.1

About this documentation

This documentation is part of the documentation category of SINUMERIK Function Manuals.

SINUMERIK Function Manuals

The SINUMERIK Function Manuals describe the NC functions of a SINUMERIK control.

The target group are configuring engineers, technologists, commissioning engineers and

programmers.

Each Function Manual covers a specific topic and contains all the function descriptions for this

topic.

The following table shows which Function Manuals are available for your SINUMERIK control and

which topics a Function Manual covers:

Function Manual

Topic

Basic functions

Basic functions of a CNC control

Axes and spindles

Axis and spindle functions, axis couplings

Transformations

Transformation functions

Monitoring and compensating

Axis monitoring and compensation functions, collision avoid-

ance

Tools

Functions for selection, correction and monitoring of tools

Synchronized actions

Functionality of synchronized actions

PLC

Structure and functions of the PLC

Tool management

Function, commissioning and programming of tool manage-

ment

Technologies (for SINUMERIK ONE

Extended technological functionalities

and SINUMERIK 840D sl only)

Overview of contents

You will find an overview of the main chapters of the descriptions of functions that are contained

in a Function Manual on the title page.

Validity

The title page also contains all data about the validity of a document, i.e. for which SINUMERIK

control and for which software version this edition of the Function Manual is valid.

Axes and spindles

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Introduction

1.1 About this documentation

System data

In the descriptions of functions, the system data relevant for a function (machine data, setting

data, system variables, interface signals and alarms) are only described with the level of detail

that is strictly necessary to understand the function. You will find detailed information on this

data in the relevant List Manuals and for alarms in the Diagnostics Manual.

PLC blocks

The descriptions of functions often refer to the PLC function blocks (FB) and functions (FC). The

descriptions of these blocks apply to the SINUMERIK 840D sl and can only be applied in part to

other SINUMERIK controls.

Interface signals

In this document, only the absolute address valid for the SINUMERIK 840D sl is used to address

interface signals.

General graphical conventions

Examples

<signal address> (<signal name>)

DB31, ... DBX16.0-2 (actual gear stage A to C)

DB31, ... DBX16.3 (gear is changed)

Note

Quantity structure

Explanations concerning the NC/PLC interface are based on the absolute maximum number of

the following components:

• Mode groups (DB11)

• Channels (DB21, etc.)

• Axes/spindles (DB31, etc.)

Axes and spindles

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Fundamental safety instructions

2

2.1

General safety instructions

WARNING

Danger to life if the safety instructions and residual risks are not observed

If the safety instructions and residual risks in the associated hardware documentation are not

observed, accidents involving severe injuries or death can occur.

• Observe the safety instructions given in the hardware documentation.

• Consider the residual risks for the risk evaluation.

WARNING

Malfunctions of the machine as a result of incorrect or changed parameter settings

As a result of incorrect or changed parameterization, machines can malfunction, which in turn

can lead to injuries or death.

• Protect the parameterization against unauthorized access.

• Handle possible malfunctions by taking suitable measures, e.g. emergency stop or

emergency off.

2.2

Warranty and liability for application examples

Application examples are not binding and do not claim to be complete regarding configuration,

equipment or any eventuality which may arise. Application examples do not represent specific

customer solutions, but are only intended to provide support for typical tasks.

As the user you yourself are responsible for ensuring that the products described are operated

correctly. Application examples do not relieve you of your responsibility for safe handling when

using, installing, operating and maintaining the equipment.

2.3

Security information

Siemens provides products and solutions with industrial security functions that support the

secure operation of plants, systems, machines and networks.

In order to protect plants, systems, machines and networks against cyber threats, it is necessary

to implement - and continuously maintain - a holistic, state-of-the-art industrial security

concept. Siemens’ products and solutions constitute one element of such a concept.

Customers are responsible for preventing unauthorized access to their plants, systems,

machines and networks. Such systems, machines and components should only be connected to

Axes and spindles

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3.2 Axisspecific referencing

Start

Referencing the machine axis can be manually started, or from the part program:

• Manual: Operation mode JOG and MDI, machine function REF

• Part program: Command G74

3.2

Axisspecific referencing

For axis-specific referencing using the reference point approach, the operation must be

individually started for each machine axis to be referenced.

Selecting mode and machine function

Before starting reference point approach of the machine axes, you must first place the relevant

mode group in JOG or MDI mode:

DB11, ... DBX0.2 (active JOG mode)

DB11, ... DBX0.1 (active MDI mode)

Then machine function REF (reference point approach) must be selected:

DB11, ... DBX1.2 (REF machine function)

Start of reference point approach

In axis-specific reference point approach, each machine axis must be started individually.

Reference point approach is started with the axis-specific traversing keys:

DB31, ... DBX4.6 (Traversing key minus)

DB31, ... DBX4.7 (Traversing key minus)

Direction enable

To avoid operator errors, the direction release must be parameterized. The direction enable

specifies which traversing key starts the reference point approach:

MD34010 $MA_REFP_CAM_DIR_IS_MINUS = <value>

<Value>

Meaning

0

Reference point approach in plus direction

1

Reference point approach in minus direction

Jog mode

The following machine data element can be used to specify whether reference point approach

is completed when the direction key is pressed once or whether the operator is required to keep

the direction key pressed (jogging) for safety reasons:

MD11300 $MN_JOG_INC_MODE_LEVELTRIGGRD (INC and REF in jog mode)

Axes and spindles

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3.3 Channelspecific referencing

DB11, ... DBX0.7 (mode group reset)

DB21, ... DBX7.7 (channel reset)

All machine axes that have not yet successfully completed reference point approach when the

action is cancelled remain in status "Not referenced":

DB31, ... DBX60.4 (referenced/synchronized 1)

DB31, ... DBX60.5 (referenced/synchronized 2)

3.3

Channelspecific referencing

For channel-specific referencing, all machine axes of the channel are referenced in the

parameterized sequence when reference point approach is initiated.

Selecting mode and machine function

Before starting the reference point approach of the machine axes, the associated mode group

must be switched into the JOG or MDI operating mode:

DB11, ... DBX0.2 (active JOG mode)

DB11, ... DBX0.1 (active MDI mode)

Then machine function REF (reference point approach) must be selected:

DB11, ... DBX1.2 (REF machine function)

Parameterizing the axis sequence

The following machine data element is used to specify the sequence in which the machine axes

of the channel are referenced:

MD34110 $MA_REFP_CYCLE_NR = <number>

<number>

Meaning

-1

The machine axis does not have to be referenced for NC START in the channel.

0

The machine axis does not participate in channel-specific reference point approach.

1 - 15

Sequence number in channel-specific reference point approach.

The machine axes are referenced in ascending order of numbers.

Machine axes with the same number will be referenced simultaneously.

Simultaneous reference point approach of several machine axes

Several machine axes can be referenced simultaneously, depending on the control:

Start of reference point approach

Channel-specific reference point approach is started with:

DB21, ... DBX1.0 (activate referencing)

Axes and spindles

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3.5 Referencing with incremental measurement systems

Programming

Syntax

G74 <machine axis> {<machine axis>}

Meaning

G74:

Command for referencing machine axes

Alone in the

Yes

block:

Effectiveness:

Non-modal

<machine axis>:

The name of a machine axis must be specified (MD10000 $MN_AXCONF_MA-

CHAX_NAME_TAB).

The machine axis must be a channel axis of the channel in which the part

program or the synchronized action is executed.

Reset behavior

Mode group reset or channel reset aborts the reference point approach for all programmed

machine axes:

• DB11, ... DBX0.7 (mode group reset)

• DB21, ... DBX7.7 (channel reset)

All machine axes for which the reference point approach is not yet successfully completed when

the action is canceled remain in status "Not referenced":

• DB31, ... DBX60.4 (referenced/synchronized 1) == 0

• DB31, ... DBX60.5 (referenced/synchronized 2) == 0

3.5

Referencing with incremental measurement systems

3.5.1

Hardware signals

Depending on the machine design and the properties of the incremental measuring system

used, different hardware signals must be connected.

Reference cam

• Connection

The reference cam signal can be connected to a digital input of an external PLC I/O module

or to a fast input on the NCU X142 interface.

• NC/PLC interface signal

The reference cam signal must be transferred from the PLC user program to the axial NC/PLC

interface:

DB31, ... DBX12.7 (deceleration of reference point approach)

Axes and spindles

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3.5 Referencing with incremental measurement systems

Zero mark selection

If during the reference point approach of the axis or spindle several zero marks of the measuring

system are detected (e.g. measuring gearbox between the motor and encoder), then the

specific zero mark must be selected with an additional contact-free proximity switch signal.

• Connection

The contact-free proximity switch must be connected to a fast digital input on the NCU

interface X122 or X132.

• Activation

In order that the proximity switch signal is evaluated, the digital input to which the proximity

switch is connected must be selected in drive parameter p0493 for the axis/spindle.

Equivalent zero mark

If the used measuring system does not provide a zero mark signal, an equivalent zero mark can

be created via a proximity switch signal.

• Connection

The contact-free proximity switch must be connected to a fast digital input on the NCU

interface X122 or X132.

• Activation

In order that the proximity switch signal is evaluated, the digital input to which the proximity

switch is connected must be selected in the p0494 or p0495 drive parameter for the axis/

spindle.

Overview

Signal

Connection: digital input via

Set

Reference cam

external PLC I/O module

PLC user program:

DB31, ... DBX12.7

or

NCU: X142

Zero mark selection

NCU: X122 or X132

Drive parameter: p0493

External zero mark or equivalent

NCU: X122 or X132

Drive parameter: p0494 or p0495

zero mark

Additional information

• NCU interfaces: Equipment Manual

Connect > Digital inputs/outputs

• Drive parameter: SINAMICS S120/S150 List Manual

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3.5 Referencing with incremental measurement systems

3.5.2

Zero mark selection

Function

Referencing of incremental measuring systems is based on the unique position of the encoder

zero mark relative to the overall traversing range of the machine axis. If because of machine-

specific conditions, several encoder zero marks are detected in the traversing range of the

machine axis (for examples, see figure below), a proximity switch must be mounted on the

machine for clear determination of the reference point. The position of the reference point is

then derived from the combination of contact-less proximity switch signal and encoder zero

mark.

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Measuring gear between the motor and encoder or reduction gear between the motor and

spindle

Parameterization

NC: Referencing mode

"Referencing of incremental, rotary or linear measuring systems: Zero pulse on the encoder

track" should be parameterized as referencing mode:

MD34200 $MA_ENC_REFP_MODE[<axis>] = 1

Drive: Zero mark selection

The digital input on the NCU interface to which the proximity switch is connected must be set

in parameter p0493.

Note

Zero mark selection

The processing of the contact-less proximity switch signal is performed exclusively in the drive.

Connection and parameterization, see Section "Hardware signals (Page 36)".

Axes and spindles

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3.5 Referencing with incremental measurement systems

3.5.3

Time sequence

Reference point approach with incremental measuring systems can be divided into three

phases:

• Phase 1: "Phase 1: Traversing to the reference cam (Page 40)"

• Phase 2: "Phase 2: Synchronization with the zero mark (Page 42)"

• Phase 3: "Phase 3: Traversing to the reference point (Page 47)"

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Time sequence when referencing with incremental measuring systems (example)

Axes and spindles

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3.5 Referencing with incremental measurement systems

3.5.4

Phase 1: Traversing to the reference cam

Phase 1: Graphic representation

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Figure 3-3

Phase 1: Traversing to the reference cam

Phase 1: Start

To start the reference point approach, see Sections "Axisspecific referencing (Page 32)" and "Axis-

specific referencing (Page 32)".

Phase 1: Sequence

In Phase 1, depending on the position of the machine axis with reference to the reference cam,

we distinguish between three cases:

1. The machine axis is positioned before the reference cam

2. The machine axis is positioned on the reference cam

3. The machine axis has no reference cam

Axes and spindles

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3.5 Referencing with incremental measurement systems

Case 1: The machine axis is positioned before the reference cam

After the start of reference point approach, the machine axis is accelerated in the parameterized

direction and to the parameterized reference point approach velocity :

• MD34010 $MA_REFP_CAM_DIR_IS_MINUS (reference point approach in minus direction)

• MD34020 $MA_REFP_VELO_SEARCH_CAM (reference point approach velocity)

The reaching of the reference cam must detected by querying a digital input in the PLC user

program and communicated to the NC via the following interface signal:

DB31, ... DBX12.7 = 1 (reference point approach deceleration)

With detection of the NC/PLC interface signal, the machine axis is decelerated to zero speed.

Whereby at least the distance s_min is traversed. This ensures that the machine axis leaves the

reference cam in Phase 2 with the parameterized reference point creep velocity.

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Minimum distance for deceleration

Case 2: The machine axis is positioned on the reference cam

The machine axis remains at its starting position.

Phase 1 is now complete. Reference point approach is continued with Phase 2.

Case 3: The machine axis has no reference cam

Machine axes without reference cams remain at their starting position.

These include, for example:

• Machine axes that only have one zero mark along their entire traversing range

• Rotary axes that only have one zero mark per revolution

Zero must be entered in the following machine data for machine axes without a reference cam:

MD34000 $MA_REFP_CAM_IS_ACTIVE = 0 (axis with reference cam)

Phase 1 is now complete. Reference point approach is continued with Phase 2.

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3.5 Referencing with incremental measurement systems

Phase 1: Properties

• Feedrate override is active.

• Feed stop (channel-specific and axis-specific) is active.

• NC stop and NC start are active.

• The machine axis is stopped if the reference cam is not reached within the parameterized

maximum distance:

MD34030 $MA_REFP_MAX_CAM_DIST (max. distance to the reference cam)

See also

Channelspecific referencing (Page 34)

3.5.5

Phase 2: Synchronization with the zero mark

Phase 2: Graphic representation

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Figure 3-5

Phase 2: Synchronization with the zero mark

Phase 2: Start

Phase 2 is automatically started when Phase 1 has been completed without an alarm.

Axes and spindles

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3.5 Referencing with incremental measurement systems

Initial situation:

The machine axis is positioned on the reference cam.

Zero mark search direction:

The direction of the zero mark search results from the settings in the machine data:

• MD34010 $MA_REFP_CAM_DIR_IS_MINUS (reference point approach in minus direction)

• MD34050 $MA_REFP_SEARCH_MARKER_REVERSE (direction reversal on reference cam)

Phase 2: Sequence

The synchronization in Phase 2 can be performed via the falling or rising edge of the reference

cam. The parameterization is performed via:

MD34050 $MA_REFP_SEARCH_MARKER_REVERSE[<axis>] = <value>

Value

Meaning

0

Synchronization with falling reference cam edge

1

Synchronization with rising reference cam edge

Note

If the actual velocity of the machine axis at approach of the reference cam has not yet reached

the target velocity of Phase 2 within the parameterized tolerance limits, Phase 1 will be

restarted. This will be the case, for example, if the machine axis is positioned on the reference

cam when reference point approach is started.

MD35150 $MA_SPIND_DES_VELO_TOL (spindle speed tolerance)

Case 1: Synchronization with falling reference cam edge

During synchronization with falling reference cam edge, the machine axis accelerates to the

parameterized reference point creep velocity opposite to the parameterized reference point

approach direction (traversing direction of Phase 1)

After leaving the reference cam, the machine axis waits for the next encoder zero mark:

DB31, ... DBX12.7 == 0

As soon as the encoder zero mark is detected, Phase 2 comes to an end. The machine axis

continues at constant velocity and reference point approach is continued with Phase 3.

• MD34040 $MA_REFP_VELO_SEARCH_MARKER (reference point creep velocity)

Axes and spindles

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3.5 Referencing with incremental measurement systems

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Synchronization with falling reference cam edge

Case 2: Synchronization with rising reference cam edge

During synchronization with rising reference cam signal edge, the machine axis accelerates to

the parameterized reference point approach velocity against the parameterized reference point

approach direction (traversing direction of the Phase 1):

• MD34020 $MA_REFP_VELO_SEARCH_CAM (reference point approach velocity)

• MD34010 $MA_REFP_CAM_DIR_IS_MINUS (reference point approach in minus direction)

After leaving the reference cam, the machine axis decelerated to standstill:

DB31, ... DBX12.7 == 0

The machine axis then travels back to the reference cam at the parameterized reference point

creep velocity:

MD34040 $MA_REFP_VELO_SEARCH_MARKER (reference point creep velocity)

After reaching the reference cam (DB31, ... DBX12.7 = 1), the machine axis waits for the next

encoder zero mark.

As soon as the encoder zero mark is detected, Phase 2 comes to an end. The machine axis

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Synchronization with rising reference cam edge

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3.5 Referencing with incremental measurement systems

Electronic reference cam shift

The electronic reference cam shift is used to compensate for expansions of the reference cam

caused by temperature so that synchronization is always to the same encoder zero mark:

MD34092 $MA_ REFP_CAM_SHIFT (electronic reference cam shift for incremental measuring

systems with equidistant zero marks)

With the electronic reference cam shift, synchronization is not performed immediately to the

next encoder zero mark after detection of the reference cam edge, but only after the

parameterized offset distance has been traversed.

Due to the determination of the distance traversed in the interpolator clock cycle since the

detection of the reference cam edge, the effective shift distance is s_shift:

s_{shift_min} =

MD34092 $MA_ REFP_CAM_SHIFT

s_{shift_max} =

MD34092 $MA_ REFP_CAM_SHIFT +

MD34040 $MA_REFP_VELO_SEARCH_MARKER * interpolator clock cycle

The electronic reference cam shift acts in the direction of zero mark search.

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Electronic reference cam shift

Requirement

The electronic reference cam shift is only active for machine axes with reference cam:

MD34000 $MA_REFP_CAM_IS_ACTIVE == 1

Reference cam adjustment

Encoder with equidistant zero marks

Always ensure that the reference cam of encoders that supply zero marks at equidistances is

accurately adjusted so that the correct zero mark is always detected during reference point

approach.

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3.5 Referencing with incremental measurement systems

• NC stop and NC start are not active.

• If the machine axis does not arrive at Phase 2 within the parameterized distance of the

reference mark (encoder zero mark), the machine axis will be stopped:

MD34060 $MA_REFP_MAX_ MARKER_DIST (max. distance to the reference mark)

3.5.6

Phase 3: Traversing to the reference point

Phase 3: Graphic representation

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Phase 3: Traversing to the reference point

Phase 3: Start

At the end of Phase 2 the machine axis travels at reference point creep velocity. Therefore, as

soon as Phase 2 is completed successfully without an alarm, Phase 3 is started without

interruption.

Initial situation

The encoder zero mark has been detected.

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3.5 Referencing with incremental measurement systems

Phase 3: Sequence

The machine axis moves at the assigned reference point positioning velocity:

MD34070 $MA_REFP_VELO_POS (reference point positioning velocity)

from the encoder zero mark detected in Phase 2 to the reference point.

The path s_ref to be covered is calculated from the sum of the reference point distance plus

reference point offset:

MD34080 $MA_REFP_MOVE_DIST (reference point distance)

MD34090 $MA_REFP_MOVE_DIST_CORR (reference point offset)

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Reference point position

When the reference point is reached, the machine axis is stopped and the actual-value system

is synchronized with the reference point value n specified by the NC/PLC interface.

MD34100 $MA_ REFP_SET_POS[<n>] (reference point value)

The selection of the reference point value is performed via the NC/PLC interface:

DB31, ... DBX2.4 ... 7 (reference point value 1 ... 4)

The actual-value system is synchronized to the reference point value that was selected at the

time the reference cam was reached in Phase 1 (DB31, ... DBX12.7 == 1).

The machine axis is now referenced. The interface signal is set as feedback to the PLC user

program, depending on the active measuring system:

DB31, ... DBX60.4/5 (referenced/synchronized 1/2) = 1

Features of Phase 3

• Feedrate override is active.

• Feed stop (channel-specific and axis-specific) is active.

• NC stop and NC start are active.

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3.6 Referencing with distance-coded reference marks

Special feature of Phase 3

In the following cases, the machine axis stops first after detection of the zero mark and then

traverses back to the reference point:

• Because of the reference point positioning velocity, the sum of reference point distance and

reference point offset is less than the required braking distance:

MD34080 + MD34090 < "required braking distance due to MD34070"

• The reference point is located, opposite to the current travel direction, "behind" the reference

cam.

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3.6

Referencing with distance-coded reference marks

3.6.1

General overview

Distancecoded reference marks

Measuring systems with distance-coded reference marks consist of two parallel scale tracks:

• Incremental grating

• Reference mark track

The distance between any two consecutive reference marks is defined. This makes it possible to

determine the absolute position of the machine axis when two consecutive reference marks are

crossed. For example, if the distance between the reference marks is approx. 10 mm, a traverse

path of approx. 20 mm is all that is required to reference the machine axis.

Referencing can be performed from any axis position in the positive or negative direction

(exception: end of travel range).

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3.6 Referencing with distance-coded reference marks

3.6.2

Basic parameter assignment

Linear measuring systems.

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Figure 3-12

Glass measuring scale with distance-coded reference marks, grid spacing: 20 mm

The following data must be set to parameterize linear measuring systems:

• The absolute offset between the machine zero point and the position of the first reference

mark of the linear measuring system:

MD34090 $MA_REFP_MOVE_DIST_CORR (reference point/absolute offset)

See also below: Determining the absolute offset

• Orientation of the length measuring system (equidirectional or inverse) relative to the

machine system coordinate system:

MD34320 $MA_ENC_INVERS (length measuring system inverse to the machine system)

Rotary measuring system

For rotary measuring systems, the same applies as for linear measuring systems (see above).

Determining the absolute offset

The following procedure is recommended for the determination of the absolute offset between

the machine zero point and the position of the first reference mark of a machine axis:

1. Enter the value zero for the absolute offset:

MD34090 $MA_REFP_MOVE_DIST_CORR = 0

2. Perform reference point approach.

Note: The reference point should be approached at a point in the machine where the exact

position of the machine axis relative to machine zero can be determined easily (using a laser

interferometer, for example).

3. Read the displayed actual position of the machine axis in the machine coordinate system MCS

from the user interface, e.g. SINUMERIK Integrate.

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3.6 Referencing with distance-coded reference marks

4. Measure the actual position of the machine axes referred to the machine zero point.

5. Calculate the absolute offset and enter in MD34090.

The absolute offset is calculated with respect to the machine coordinate system and

depending on the orientation of the measuring system as:

Orientation of the measuring system

Absolute offset

Equidirectional

(Measured position) + (displayed actual position)

Opposite direction

(Measured position) - (displayed actual position)

WARNING

Reference point deviation

After determining the absolute offset and the entry in MD34090, the reference point traversing

for the machine axis must be carried out once more.

Referencing methods

Referencing with distance-coded reference marks can be performed in one of two ways:

• Evaluation of two consecutive reference marks:

MD34200 $MA_ENC_REFP_MODE = 3

Advantage:

- Short travel path

• Evaluation of four consecutive reference marks:

MD34200 $MA_ENC_REFP_MODE = 8

Advantage:

- Plausibility check by NC is possible

- Increase in reliability of referencing result

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3.6 Referencing with distance-coded reference marks

3.6.3

Time sequence

Time sequence

Referencing with distance-coded reference marks can be divided into two phases:

• Phase 1: Travel across the reference marks with synchronization

• Phase 2: Travel to a fixed destination point

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3.6.4

Phase 1: Travel across the reference marks with synchronization

Phase 1: Start

To start the reference point approach, see Sections "Axisspecific referencing (Page 32)" and

"Channelspecific referencing (Page 34)".

Reference cam

In measuring systems with distance-coded reference marks, reference cams are not required for

the actual referencing action. For functional reasons, however, a reference cam is required for

channel-specific reference point approach and reference point approach from the part program

(G74) before the traversing range end of the machine axis.

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3.6 Referencing with distance-coded reference marks

Abort criterion

If the parameterized number of reference marks is not detected within the parameterized

distance, the machine axis is stopped and reference point traversing is aborted.

MD34060 $MA_REFP_MAX_ MARKER_DIST (max. distance to the reference mark)

Features of Phase 1

After Phase 1 is successfully completed, the actual value system of the machine axis is

synchronized.

3.6.5

Phase 2: Traversing to the target point

Phase 2: Start

Phase 2 is automatically started when Phase 1 has been completed without an alarm.

Initial situation:

• The machine axis is positioned directly behind the last of the parameterized number of

reference marks.

• The actual value system of the machine axis is synchronized.

Phase 2: Sequence

In Phase 2, the machine axis completes reference point approach by traversing to a defined

target position (reference point). This action can be suppressed in order to shorten the reference

point approach:

MD34330 $MA_STOP_AT_ABS_MARKER = <value>

Value

Meaning

0

Travel to target position

1

No travel to target position

Travel to target position (normal case)

The machine axis accelerates to the parameterized reference point position velocity and travels

to the parameterized target point (reference point):

MD34070 $MA_REFP_VELO_POS (reference point positioning velocity)

MD34100 $MA_REFP_SET_POS (reference point value)

The machine axis is referenced. To identify this, the NC sets an interface signal for the measuring

system that is currently active:

DB31, ... DBX60.4/60.5 (referenced/synchronized 1/2) = 1

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3.9 Referencing with absolute encoders

3.9

Referencing with absolute encoders

3.9.1

Information about the adjustment

Machine axes with absolute encoder

The advantage of machine axes with absolute encoder is that after a one time adjustment

procedure, the necessary reference point traversing with incremental measuring systems (e.g.

build-up of control, de-selection of "Parking" of machine axes etc.) can be skipped and the actual

value system of the machine axis can be immediately synchronized to the determined absolute

position.

Adjustment

Adjustment of an absolute encoder involves matching the actual value of the encoder with the

machine zero once and then setting it to valid.

The current adjustment status of an absolute encoder is displayed in the following axis-specific

machine data of the machine axis, to which it is connected:

MD34210 $MA_ENC_REFP_STATE (status of absolute encoder)

Value

Meaning

0

Encoder not calibrated

1

Encoder adjustment enabled

2

Encoder is calibrated

Adjustment methods

The following adjustment methods are supported:

• Adjustment by entering a reference point offset

• Adjustment by entering a reference point value

• Automatic adjustment with probe

• Adjustment by means of the proximity switch

Readjustment

Readjustment of the absolute encoder is required after:

• Gear change between load and absolute encoder

• Removal/installation of the absolute encoder

• Removal/installation of the motor with the absolute encoder

• Data loss in the static NC memory

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3.9 Referencing with absolute encoders

•

Battery failure

•

Set actual value (PRESETON)

WARNING

Data backup

During the back-up of machine data of a machine A, the encoder status of the machine axis

(MD34210) is also backed up.

During loading of this data record into a machine B of the same type, e.g. in the context of

a serial start-up or after a case of maintenance, the referenced machine axes will be

automatically regarded as adjusted / referenced by the NC. It is the special responsibility of

the machine manufacturer / user to undertake a readjustment in such cases.

See also explanations regarding machine data:

MD30250 $MA_ACT_POS_ABS (absolute encoder position at the time of switch-off)

Note

The controller can detect a required readjustment of the absolute encoder only during the

following events:

• Gear change with change of gear ratio

• Addressing the zero-mark monitoring

• New encoder serial number after change of the absolute encoder

The controller then sets the status of the absolute encoder to "0":

MD34210 $MA_ENC_REFP_STATE = 0 (encoder not adjusted)

The following alarm is displayed:

Alarm 25022 "Axis <axis name> encoder <number> warning 0"

If the zero-mark monitoring responds, the following alarm is also displayed:

Alarm 25020 "Axis <axis name> zero-mark monitoring of active encoder"

In all other cases (e.g. PRESETON) it is the sole responsibility of the user to display the

misalignment of the absolute encoder by manually setting the status to "0" and to carry out

a readjustment.

3.9.2

Calibration by entering a reference point offset

Function

During adjustment by entering the reference point offset, the difference between the position

displayed on the operator interface and the true actual position in the machine is determined

and made known to the NC as reference point offset.

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3.9 Referencing with absolute encoders

Procedure

1.

Determining the position of the machine axis with reference to the machine zero point via

e.g.:

- position measurement (e.g. laser interferometer)

- Moving the machine axis to a known position (e.g., fixed stop)

2.

Reading the displayed actual position of the machine axis on the operator interface.

3.

Calculating the reference point offset (difference between the actual positions determined

under point 1 and 2) and entering in machine data:

MD34090 $MA_REFP_MOVE_DIST_CORR (reference point offset)

4.

Marking the absolute value encoder as adjusted:

MD34210 $MA_ENC_REFP_STATE = 2

Note

The encoder adjustment does not become active until the next time the encoder is activated

(e.g., when the controller is powered up).

5.

Initiate POWER ON reset.

6.

Controlling the position of the machine axis displayed on the operator interface.

Note

Backlash compensation

If backlash compensation is parameterized for a measuring system with absolute value

encoder, the following must be observed:

No backlash is permitted during machine axis travel to the adjusted machine position.

Activate reference point offset permanently

The entered reference point offset (MD34090) will be permanently active only after initial

POWER ON - Reset. If the machine axis is moved after the absolute encoder adjustment

without an interim POWER ON - Reset, the reference point offset entered in the machine data

can be overwritten, for example, as part of internal overrun offset.

Checking the actual position

Following adjustment of the absolute encoder, we recommend that you verify the actual

position of the machine axis the next time you power up the controller (POWER ON).

3.9.3

Adjustment by entering a reference point value

Function

During adjustment by entering the reference point value, the absolute position of the machine

axis with reference to the machine zero point is determined by e.g.:

• Position measurement (e.g. laser interferometer)

• Moving the machine axis to a known position (e.g. fixed stop)

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3.9 Referencing with absolute encoders

7. Operate the travel key used for referencing in step 2.

The machine axis does not move when the traversing key is actuated!

The NC calculates the reference point offset from the entered reference point value and that

given by the absolute encoder. The result is entered into the machine data:

MD34090 $MA_REFP_MOVE_DIST_CORR (reference point offset)

The status of the absolute encoder is set to "Encoder is adjusted":

MD34210 $MA_ ENC_REFP_STATE = 2

The actual value system of the machine axis is synchronized.

The machine axis is now referenced. As identification, the NC sets the appropriate interface

signal based on which measuring system is currently active:

DB31, ... DBB60.4 / 60.5 (referenced/synchronized 1 / 2) = 1

8. Initiate Power On reset.

Note

Activate reference point offset permanently

The entered reference point offset (MD34090) will only be permanently active after Power

On reset.

If the machine axis is moved after the absolute encoder adjustment without an interim Power

On reset, the reference point offset entered in the machine data can be overwritten, for

example, within internal overrun corrections.

Checking the actual position

Following adjustment of the absolute encoder, we recommend that you verify the actual

position of the machine axis the next time you power up the controller (Power On).

3.9.4

Automatic calibration with probe

Function

In automatic adjustment with a probe, a known position in the machine is approached with the

machine axis from a part program. The position value is stored in the NC as a reference point

value. The position is reached when the probe switches, and the NC then calculates the

reference point offset from the difference between the encoder value and reference point value.

Note

Part program for automatic adjustment

The part program for automatic adjustment using a probe must be created by the machine

manufacturer / user for the specific requirements of the machine.

Freedom from collision

Because actual-value-related monitoring is not active for the machine axes being referenced,

the machine operator must take special care to ensure that collisions do not occur in the

machine while the machine axes are being moved!

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3.9 Referencing with absolute encoders

Part program

The part program for automatic adjustment of absolute encoders with probe must perform the

points listed below for each axis in the order indicated:

1. Approach the adjustment position of machine axis, which is detected from the probe

response.

The position must be approached several times from the same direction, but at a velocity

which is gradually reduced on each approach, to ensure that the measured value obtained

is as accurate as possible. The measured value is stored in system variable $AA_IM.

2. Calculating and writing the reference point offset:

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3. Set the absolute encoder status to "Encoder is adjusted":

MD34210 $MA_ ENC_REFP_STATE = 2

Sequence

Proceed as follows for automatic adjustment with probe:

1. Enable part program start even for non-referenced machine axes:

MD20700 $MC_REFP_NC_START_LOCK = 0

2. Enter the machine axis position relative to machine zero when probe is switched as the

reference point value for all relevant machine axes:

MD34100 $MA_REFP_SET_POS = reference point value

3. Activate NCK-Reset for the acceptance of the entered machine data values.

4. Start part program.

5. After completion of the part program, re-secure the partial program start for machine axes

which are not referenced:

MD20700 $MC_REFP_NC_START_LOCK = 1

6. Initiate POWER ON - Reset so that the reference point offset written by the part program is

permanently active:

MD34090 $MA_REFP_MOVE_DIST_CORR (reference point offset)

Note

Activate reference point offset permanently

The entered reference point offset (MD34090) will only be permanently active after

POWER ON - Reset.

If the machine axis is moved after the absolute encoder adjustment without an interim

POWER ON - Reset, the reference point offset entered in the machine data can be overwritten,

for example, as part of internal overrun offset.

Checking the actual position

Following adjustment of the absolute encoder, we recommend that you verify the actual

position of the machine axis the next time you power up the controller (POWER ON).

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3.9 Referencing with absolute encoders

3.9.6

Reference point approach with absolute encoders

Parameter assignment

Traversing movement release

If for a machine axis with adjusted absolute value encoder as active measuring system, reference

point traversing is activated (manually in the JOG-REF mode or automatically via the part

program instruction G74), the machine axis travels depending on the parameterized traversing

movement release.

MD34330 $MA_REFP_STOP_AT_ABS_MARKER = <value>

Value

Meaning

0

Traversing is enabled.

When reference point approach is initiated, the machine axis moves to the reference point

position. When reaching the reference point position, the reference point approach is comple-

ted.

1

Traversing is not enabled.

After the activation of the reference point travel, the machine axis does not travel and the

reference point travel is immediately completed.

3.9.7

Reference point approach for rotary absolute encoders with equivalent zero

mark

Function

To ensure that the reference point approach via zero mark (see Section "Referencing with

incremental measurement systems (Page 36)") can also be used with absolute encoders, the

zero mark, which is not provided in the hardware of absolute encoders, is simulated. For this, the

controller generates the signal for the equivalent zero mark once per encoder revolution, always

at the same position within the revolution.

Difference compared to referencing with incremental encoders

An absolute encoder with replacement zero mark should not be considerd as a complete

equivalent of an incremental encoder. All the properties of the absolute encoder are retained.

The following table lists the different properties of incremental and absolute encoders:

Table 3-1

Properties of incremental and absolute encoders

Property

Incremental encoder

Absolute encoder

Encoder type

MD30240 $MA_ENC_TYPE =

1

4

Internal encoder position

MD30250 $MA_ACT_POS_ABS =

Value is updated only in MD34210 ≥ 1

Value is updated only in MD30270 = 0

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3.9 Referencing with absolute encoders

Property

Incremental encoder

Absolute encoder

Traversing range extension

MD30270 $MA_ENC_ABS_BUFFERING =

No effect

= 0 (default): Active

Reference point offset

MD34090 $MA_REFP_MOVE_DIST_CORR =

Value input allowed

Value is updated exclusively via control

Supported referencing types

MD34200 $MA_ENC_REFP_MODE =

1, 3, 4, 8

0, 1

Adjustment status

MD34210 $MA_ENC_REFP_STATE = 0, 1, 2

Automatic encoder misalignment dur-

Automatic encoder misalignment during pa-

ing shut down while in motion.

rameter set change with position jump or

during serial number change.

Absolute position modulo range

MD34220 $MA_ENC_ABS_TURNS_MODULO =

0

1 - 4096

Encoder serial no.

MD34230 $MA_ENC_SERIAL_NUMBER =

0

The value must be updated from the PLC dur-

ing each encoder change, otherwise loss of

adjustment plus alarm.

Transfer of series startup files

Without any restrictions.

Due to encoder characteristics (MD30250,

MD30270, MD34090, MD34210, MD34220,

MD34230) only possible with certain restric-

tions.

Activation time

0 seconds

several seconds

Zero mark

1 per encoder revolution

None

Zero mark monitoring

Hardware

Software

Position after POWER ON without

0.0

Last position within MD34220.

actual value buffering

MD34210 = 0

MD30270 = 1

Position after POWER ON with ac-

Last standstill position before deactiva-

Last position including small movements dur-

tual value buffering

tion.

ing POWER OFF.

MD34210 = 1

MD30270 = 0

Referenced after POWER ON

depends on adjustment status

Requirement

The function can be used only with rotary absolute encoders:

• MD31000 $MA_ENC_IS_LINEAR == 0

• MD30240 $MA_ENC_TYPE == 4

Parameterization

Reference point approach with equivalent zero mark:

MD34200 $MA_ENC_REFP_MODE = 1

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3.9 Referencing with absolute encoders

Parameterizing the encoder limit frequency (spindles)

The EQN 1325 absolute encoder made by Heidenhain has an incremental track and an absolute

track.

If a spindle is driven at a speed above the encoder limit frequency of the incremental track, the

substantially lower limit frequency of absolute track must be parameterized as the encoder limit

frequency.

MD36300 $MA_ENC_FREQ_LIMIT

Otherwise an incorrect absolute position would be read because the parameterized encoder

limit frequency is not reached when the measuring system is activated. This would cause a

position offset in the actual value system of the machine axis.

Determining the encoder limit frequency

The encoder limit frequency to be parameterized is derived from the smaller of the two following

limit speeds:

• Encoder

The limit speed or encoder limit frequency is listed in the data sheet of the encoder (e.g., limit

speed = 2000 [rpm])

• NC

Due to the NC-internal evaluation process, the maximum limit speed for which error-free

calculation of the absolute value by the NC is possible is 4 encoder revolutions per

interpolator clock cycle.

For an interpolator clock cycle of, for example, 12 ms: Limit speed = 4 / 12 ms = 20,000 rpm

The limiting frequency corresponding to the limiting speed is calculated to be:

0'

0'

0'

0'

MD31020 $MA_ENC_RESOL (encoder pulses per revolution)

MD10050 $MN_SYSCLOCK_CYCLE_TIME (basic system clock cycle)

MD10070 $MN_IPO_SYSCLOCK_TIME_RATIO (factor for the interpolation cycle)

Note

The position control switching speed relevant for spindles is set according to the encoder

limiting frequency of the absolute value encoder of the spindle:

MD35300 $MA_SPIND_POSCTRL_VELO (position control switching speed)

MD36300 $MA_ENC_FREQ_LIMIT (Encoder limit frequency)

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3.10 Automatic restoration of the machine reference

3.9.9

Referencing variants not supported

The following referencing variants are not supported when used with absolute encoders:

• Referencing/calibrating with encoder zero mark

• Distance-coded reference marks

• Proximity switch with two-edge evaluation

3.10

Automatic restoration of the machine reference

3.10.1

Overview

Without a defined machine reference when traversing machine axes, no position-dependent

functions such as transformations or tool frames can be executed. In different machine

situations, these functions must immediately be available for traversing axes when the encoder

is activated, e.g. after the controller is switched on or after the parking of a machine axis has

ended (see Function Manual "Monitoring and Compensating"). However, the machine axes

should not or cannot be traversed again for referencing.

Absolute encoders

For measuring systems with adjusted absolute encoders, the machine reference is restored

immediately without any additional measures when the encoder value is read.

Incremental encoders

With incremental measuring systems, the machine reference can be restored without traversing

the axes through "Automatic referencing" or "Restoration of the actual position".

Boundary conditions

WARNING

Incorrect synchronization of the position measuring system caused by offset of the actual

machine axis position

During the time in which the measuring system of the machine axis is switched off, it is not

permissible that the axis is mechanically moved. Otherwise this results in an offset between the

last buffered actual position and the real actual position of the machine axis. This would lead

to an incorrect synchronization of the measuring system resulting in danger to personnel and

machine.

The machine manufacturer must provide such measures as holding brakes, etc. on the machine

so that the actual position is not changed, and this must be ensured by the user. The

responsibility for this rests exclusively with the machine manufacturer / user.

If axis motion cannot be prevented mechanically in the shutdown state, either an absolute

encoder must be used or the axis must be referenced again with reference point approach after

switching on.

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3.10 Automatic restoration of the machine reference

Note

SMExx Sensor Modules

Automatic referencing or restoration of the actual position to the last buffered position after

restarting the control is only possible in conjunction with SMExx (externally mounted) Sensor

Modules. When using SMCxx (cabinet) or SMIxx (integrated) Sensor Modules, the actual

position cannot be restored after restarting the control (power on). The measuring system of

the machine axis must be referenced again.

3.10.2

Automatic referencing

Function

During automatic referencing, the actual position of the active measuring system of the

machine axis is set to the last buffered position and "referenced" set as encoder state after

switching on the control. This makes it possible to start programs in the AUTOMATIC and MDI

modes directly after run-up of the control.

Requirements

• The active measuring systems when the control is switched on must already have been

referenced once before switching off.

• At the time the control is switched off, the machine axis must be at standstill with "Exact stop

fine" (DB31, ... DBX60.7 == 1) are located.

Note

If the machine axis is not at standstill with "Exact stop fine" when switching off, the actual

position will be initialized with " 0" when switching on. "Not referenced" is displayed as the

encoder state.

Parameterization

The automatic referencing is enabled by setting the encoder state to "Automatic referencing is

enabled, but the encoder has not been referenced":

MD34210 $MA_ENC_REFP_STATE[<encoder>] = 1

After the measuring system has been referenced, the encoder state displays that automatic

referencing will be executed the next time the encoder is activated:

MD34210 $MA_ENC_REFP_STATE[<encoder>] == 2

NC/PLC interface signals

After automatic referencing, the encoder state "Referenced" is displayed for the active

measuring system:

DB31, ... DBX60.4/.5 == 1 (referenced/synchronized 1/2)

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3.12 Data lists

3.12

Data lists

3.12.1

Machine data

3.12.1.1

NC-specific machine data

Number

Identifier: $MN_

Description

11300

JOG_INC_MODE_LEVELTRIGGRD

INC/REF in jog/continuous mode

3.12.1.2

Channelspecific machine data

Number

Identifier: $MC_

Description

20700

REFP_NC_START_LOCK

NC start disable without reference point

3.12.1.3

Axis/spindlespecific machine data

Number

Identifier: $MA_

Description

30200

NUM_ENCS

Number of encoders

30240

ENC_TYP

Actual value encoder type

30242

ENC_IS_INDEPENDENT

Encoder is independent

30250

ACT_POS_ABS

Absolute encoder position at time of deactivation

30270

ENC_ABS_BUFFERING

Absolute encoder: Traversing range extension

30300

IS_ROT_AX

Rotary axis / spindle

30310

ROT_IS_MODULO

Modulo conversion for rotary axis / spindle

30330

MODULO_RANGE

Size of the modulo range

30340

MODULO_RANGE_START

Starting position of modulo range

30355

MISC_FUNCTION_MASK

Axis functions

31122

BERO_DELAY_TIME_PLUS

BERO delay time in plus direction

31123

BERO_DELAY_TIME_MINUS

BERO delay time in minus direction

34000

REFP_CAM_IS_ACTIVE

Axis with reference cam

34010

REFP_CAM_DIR_IS_MINUS

Reference point approach in minus direction

34020

REFP_VELO_SEARCH_CAM

Reference point approach velocity

34030

REFP_MAX_CAM_DIST

Maximum distance to reference cam

34040

REFP_VELO_SEARCH_MARKER

Reference point creep velocity

34050

REFP_SEARCH_MARKER_REVERSE

Direction reversal on reference cam

34060

REFP_MAX_MARKER_DIST

Maximum distance to reference mark;

maximum distance to two reference marks with dis-

tance-coded scales

34070

REFP_VELO_POS

Reference point positioning velocity

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Homing

3.12 Data lists

Number

Identifier: $MA_

Description

34080

REFP_MOVE_DIST

Reference point distance / destination point for distance-

coded system

34090

REFP_MOVE_DIST_CORR

Reference point offset / absolute offset, distance-coded

34092

REFP_CAM_SHIFT

Electronic reference cam shift for incremental measur-

ing systems with equidistant zero marks

34093

REFP_CAM_MARKER_DIST

Reference cam / reference mark distance

34100

REFP_SET_POS

Reference point value

34102

REFP_SYNC_ENCS

Actual value adjustment to the referencing measure-

ment system

34104

REFP_PERMITTED_IN_FOLLOWUP

Enable referencing in follow-up mode

34110

REFP_CYCLE_NR

Axis sequence for channel-specific referencing

34120

REFP_BERO_LOW_ACTIVE

Polarity change of the BERO cam

34200

ENC_REFP_MODE

Referencing mode

34210

ENC_REFP_STATE

Status of absolute encoder

34220

ENC_ABS_TURNS_MODULO

Absolute encoder range for rotary encoders

34230

ENC_SERIAL_NUMBER

Encoder serial number

34232

EVERY_ENC_SERIAL_NUMBER

Range of the encoder serial number

34300

ENC_REFP_MARKER_DIST

Basic reference mark distance for distance-coded en-

coders

34310

ENC_MARKER_INC

Interval between two reference marks with distance-co-

ded scales

34320

ENC_INVERS

Linear measuring system inverse to machine system

34330

REFP_STOP_AT_ABS_MARKER

Distance-coded linear measuring system without desti-

nation point

35150

SPIND_DES_VELO_TOL

Spindle speed tolerance

36302

ENC_FREQ_LIMIT_LOW

Encoder limit frequency resynchronization

36310

ENC_ZERO_MONITORING

Zero mark monitoring

Axes and spindles

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Acceleration and jerk

4.2 Detailed description

4.2

Detailed description

4.2.1

Acceleration without jerk limitation (BRISK/BRISKA) (channel/axis-specific)

4.2.1.1

Function

In the case of acceleration without jerk limitation (jerk = infinite) the maximum value is applied

for acceleration immediately. As regard to acceleration with jerk limitation, it differs in the

following respects:

• Advantages

Shorter processing times with the same maximum values for velocity and acceleration.

• Disadvantages

Increased load on the machine's mechanical components and risk of inducing high-

frequency and difficult-to-control mechanical vibrations.

Acceleration profile

D

D_PD[

W

D_PD[

Y

Y_PD[

W

W

W

W

a_max:

Maximum acceleration value

v_max:

Maximum velocity value

t:

Time

Figure 4-1

Velocity and acceleration schematic for stepped acceleration profile

The following features of the acceleration profile can be identified from the figure above:

• Time: t₀

Sudden acceleration from 0 to +a_max

• Interval: t₀ - t₁

Constant acceleration with +a_max; linear increase in velocity

Axes and spindles

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Acceleration and jerk

4.2 Detailed description

• Time: t

1

Sudden acceleration from 2 * a_max with immediate switchover from acceleration to braking

Note

The sudden acceleration can normally be avoided by specifying a constant velocity time (see

Section "Constant traversing time (channel-specific) (Page 84)").

• Interval: t₁ - t₂

Constant acceleration with -a_max; linear decrease in velocity

4.2.1.2

Parameterization

Maximum axial acceleration for path motions

The maximum axial acceleration for path motions can be set for the specific technology for each

machine axis via the following machine data:

MD32300 $MA_MAX_AX_ACCEL[<parameter set index>]

With <parameter set index> = 0, 1, 2 ... (max. parameter set number - 1)

For further information about the technology-specific parameter sets, see the Basic Functions

Function Manual.

The path parameters are calculated by the path planning of the preprocessing so that the

parameterized maximum values of the machine axes involved in the path are not exceeded.

Note

It is possible for the maximum value to be exceeded in connection with specific machining

situations (see Sections "Acceleration adaptation (ACC) (axis-specific) (Page 86)" and "Path

acceleration for real-time events (channel-specific) (Page 90)").

Maximum axial acceleration for positioning axis motions

With positioning axis motions, one of the two following maximum values is effective depending

on the set positioning axis dynamic response mode:

• MD32300 $MA_MAX_AX_ACCEL [0] (maximum axial acceleration for path motions in the

dynamic response mode DYNNORM)

• MD32300 $MA_MAX_AX_ACCEL [1] (maximum axial acceleration for path motions in the

dynamic response mode DYNPOS)

The positioning axis dynamic response mode is set in the NC-specific machine data:

MD18960 $MN_POS_DYN_MODE = <mode>

<mode>

Meaning

0

Effective maximum axial acceleration: MD32300 $MA_MAX_AX_ACCEL[ 0 ]

1

Effective maximum axial acceleration: MD32300 $MA_MAX_AX_ACCEL[ 1]

Axes and spindles

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Acceleration and jerk

4.2 Detailed description

D

D

PD[

W

D_PD[

Y

Y_PD[

W

W

W

W

W

W

W

1:

Curve with constant traversing time

2:

Curve without constant traversing time

a_max: Maximum acceleration value

v_max: Maximum velocity value

t:

Time

Figure 4-2

Principle characteristic for an abrupt acceleration

The above figure shows the effect of the constant traversing time:

• Time: t₁

End of the acceleration phase with acceleration jump 1 * a_max

• Interval: t₁ - t₂

Acceleration 0; constant velocity over the parameterized constant traversing time

• Time: t₂

Start of the braking phase with acceleration jump 1 * a_max

The instants t₀, t₁' and t₂' indicate the associated curve that would have resulted without

constant traversing time.

4.2.2.2

Parameterization

The constant travel time is parameterized for specific channels using machine data:

MD20500 $MC_CONST_VELO_MIN_TIME

(minimum time with constant velocity)

Axes and spindles

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Acceleration and jerk

4.2 Detailed description

4.2.3

Acceleration adaptation (ACC) (axis-specific)

4.2.3.1

Function

Using the ACC command, the currently effective maximum axis acceleration parameterized in

the acceleration-specific machine data can be reduced for a specific axis. The reduction is in the

form of a percentage factor, which is specified when programming the command.

For instance, reducing the maximum possible axis acceleration in a machining segment can be

used to prevent mechanical vibration as a result of high machining forces.

Effectiveness

Reducing the acceleration with ACC is effective for all interpolation types in the AUTOMATIC and

MDI operating modes - and for the dry run feedrate.

Acceleration reduction is not effective:

• in the JOG mode

• During the machine function REF (reference point approach).

• If, as a result of a fault that has been detected, the axis is stopped with a fast stop (setpoint

= 0).

4.2.3.2

Programming

Syntax

ACC[<axis>]=<reduction factor>

ACC[SPI(<spindle number>)]=<reduction factor>

ACC(S<spindle number>)=<reduction factor>

Meaning

<ACC>:

Command for the axis-specific reduction of the currently maximum possible

acceleration, derived from the machine data

Effectiveness:

Modal

<axis>:

Channel axis name of path axis

Data type:

AXIS

Value range:

Channel axis names

SPI(<spindle

The SPI(...) function converts the spindle number into the corresponding

number>):

channel axis name.

S<spindle

Spindle name in the channel

number>:

Further information

System variable

The acceleration reduction (set using ACC), currently active in the channel, can be read on an

axis-for-axis basis using:

Axes and spindles

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Acceleration and jerk

4.2 Detailed description

4.2.6

Limiting the path acceleration (PACCLIM)

With the function "Adapt maximum path acceleration", the acceleration of the path motion

resulting from the axial limitation values can be reduced in critical program sections in the part

program. The acceleration value to which the maximum path acceleration is to be reduced is

programmed via the address PACCLIM. The programmed value is always effective only until the

next NC reset or the end of the part program.

Requirements

Licensing

A license is required for this optional function ("Path acceleration limitation", article number:

6FC5800-0xP26-0YB0) and must be assigned to the hardware via the license management.

Effectiveness

The function is effective:

• In the AUTOMATIC operating modes

• Only on path axes

Syntax

PACCLIM=<Value>

PACCLIM=-1

Meaning

PACCLIM

Address for adjusting the maximum path acceleration

<Value>

Acceleration value to which the maximum path acceleration is to be reduced

Data type:

REAL

Value range:

1.0 * 10^-6 ... 1.0 * 10³⁸

Unit:

m/s² or inch/s² (depending on the active system of units)

PACCLIM=-1

Cancels the limit programmed by PACCLIM=<Value>.

Note

The effect of PACCLIM is similar to the effect of the setting data SD42500

$SC_SD_MAX_PATH_ACCEL (maximum path acceleration). In contrast to SD42500, however,

PACCLIM works block-synchronously.

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