Omron CJ1W-MCH72 OPERATION MANUAL
Cat. No. I55E-EN-03
Programmable Controller
SYSMAC CJ-series
CJ1W-MCH72
Motion Control Unit
OPERATION MANUAL
Notice
OMRON products are manufactured for use by a trained operator and only for the purposes described in this
manual.
The following conventions are used to classify and explain the precautions in this manual. Always heed the
information provided with them.
!WARNING Indicates information that, if not heeded, could possibly result in serious injury or loss of life.
!Caution Indicates information that, if not heeded, could possibly result in minor or relatively serious injury,
damage to the product or faulty operation.
OMRON product references
All OMRON products are capitalized in this manual.
The first letter of the word Unit is also capitalized when it refers to an OMRON product, regardless of whether it
appears in the proper name of the product.
The abbreviation PLC means Programmable Logic Controller.
Visual aids
The following headings appear in the left column of the manual to help you locate different types of information.
Note Indicates information of particular interest for efficient and convenient operation of the product.
iii
Trademarks and copyrights
MECHATROLINK is a registered trademark of Yaskawa Corporation.
Trajexia is a registered trademark of OMRON.
All other product names, company names, logos or other designations mentioned herein are trademarks of their
respective owners.
Copyright
Copyright © 2009 OMRON
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in
any form, or by any means, mechanical, electronic, photocopying, recording, or otherwise, without the prior
written permission of OMRON.
No patent liability is assumed with respect to the use of the information contained herein. Moreover, because
OMRON is constantly striving to improve its high-quality products, the information contained in this manual is
subject to change without notice. Every precaution has been taken in the preparation of this manual.
Nevertheless, OMRON assumes no responsibility for errors or omissions. Neither is any liability assumed for
damages resulting from the use of the information contained in this publication.
iv
TABLE OF CONTENTS
Precautions vii
1 Intended audience ....................................................................................................................................................vii
2 General precautions .................................................................................................................................................vii
3 Safety precautions....................................................................................................................................................vii
4 Operating environment precautions........................................................................................................................viii
5 Application precautions ............................................................................................................................................ix
6 Conformance to EC Directives................................................................................................................................. xi
SECTION 1
Introduction 1
1-1 Overview....................................................................................................................................................................1
1-2 System philosophy..................................................................................................................................................... 2
1-3 Motion control concepts ............................................................................................................................................ 4
1-4 Servo system principles ...........................................................................................................................................13
1-5 Trajexia system architecture ..................................................................................................................................16
1-6 Cycle time ............................................................................................................................................................... 17
1-7 Program control and multi-tasking .......................................................................................................................... 22
1-8 Motion sequence and axes ....................................................................................................................................... 23
1-9 Motion buffers ....................................................................................................................................................... 31
1-10 Mechanical system................................................................................................................................................... 33
1-11 Axis numbers ........................................................................................................................................................... 34
SECTION 2
Installation and wiring 35
2-1 Unit components ...................................................................................................................................................... 35
2-2 Wiring ...................................................................................................................................................................... 40
2-3 Installation ............................................................................................................................................................... 50
2-4 Specifications........................................................................................................................................................... 55
SECTION 3
Data exchange 59
3-1 Introduction..............................................................................................................................................................59
3-2 Memory areas........................................................................................................................................................... 60
3-3 Data.......................................................................................................................................................................... 62
3-4 FINS commands ...................................................................................................................................................... 65
SECTION 4
BASIC commands 73
4-1 Categories ................................................................................................................................................................73
4-2 All BASIC commands ............................................................................................................................................. 84
SECTION 5
Examples 267
5-1 How-to’s ................................................................................................................................................................ 268
5-2 Practical examples ................................................................................................................................................. 320
v
TABLE OF CONTENTS
SECTION 6
Troubleshooting 347
6-1 Items to Check First...............................................................................................................................................348
6-2 Error Indicators......................................................................................................................................................349
6-3 Troubleshooting Errors..........................................................................................................................................350
6-4 Miscellaneous ........................................................................................................................................................ 356
Revision history 361
vi
Intended audience 1
Precautions
1 Intended audience
This manual is intended for the following personnel, who must also have
knowledge of electrical systems (an electrical engineer or the equivalent).
• Personnel in charge of installing FA systems.
• Personnel in charge of designing FA systems.
• Personnel in charge of managing FA systems and facilities.
2 General precautions
The user must operate the product according to the performance
specifications described in the operation manuals.
Before using the product under conditions which are not described in the
manual or applying the product to nuclear control systems, railroad systems,
aviation systems, vehicles, combustion systems, medical equipment,
amusement machines, safety equipment, and other systems, machines, and
equipment that may have a serious influence on lives and property if used
improperly, consult your OMRON representative.
Make sure that the ratings and performance characteristics of the product are
sufficient for the systems, machines, and equipment, and be sure to provide
the systems, machines, and equipment with double safety mechanisms.
This manual provides information for using the CJ1W-MCH72. Be sure to read
this manual before attempting to use the Unit and keep this manual close at
hand for reference during operation.
!WARNING It is extremely important that the CJ1W-MCH72 and related devices be used for the
specified purpose and under the specified conditions, especially in applications that can
directly or indirectly affect human life. You must consult with your OMRON
representative before applying the CJ1W-MCH72 and related devices to the above
mentioned applications.
3 Safety precautions
!WARNING Never short-circuit the positive and negative terminals of the batteries, charge the
batteries, disassemble them, deform them by applying pressure, or throw them into a
fire.
The batteries may explode, combust or leak liquid.
!WARNING The CJ1W-MCH72 outputs will go off due to overload of the output transistors
(protection). As a countermeasure for such problems, external safety measures must
be provided to ensure safety in the system.
!WARNING The CJ1W-MCH72 will turn off the WDOG when its self-diagnosis function detects any
error. As a countermeasure for such errors, external safety measures must be provided
to ensure safety in the system.
!WARNING Never attempt to disassemble any Units while power is being supplied. Doing so may
result in serious electric shock.
!WARNING Do not attempt to disassemble, repair, or modify any Units. Any attempt to do so may
result in malfunction, fire, or electric shock.
!WARNING Never touch any of the terminals while power is being supplied. Doing so may result in
serious electric shock.
vii
Operating environment precautions 4
!WARNING Provide safety measures in external circuits (i.e., not in the Programmable Controller)
to ensure safety in the system if an abnormality occurs due to malfunction of the PLC,
malfunction of the CJ1W-MCH72, or external factors affecting the operation of the PLC
or CJ1W-MCH72. Not providing sufficient safety measures may result in serious
accidents.
• Emergency stop circuits, interlock circuits, limit circuits, and similar safety measures
must be provided in external control circuits.
• The PLC will turn OFF all outputs when its self-diagnosis function detects any error
or when a severe failure alarm (FALS) instruction is executed. As a countermeasure
for such errors, external safety measures must be provided to ensure safety in the
system.
• The PLC or CJ1W-MCH72 outputs may remain ON or OFF due to deposits on or
burning of the output relays, or destruction of the output transistors. As a
countermeasure for such problems, external safety measures must be provided to
ensure safety in the system.
• When the 24 V DC output (service power supply to the PLC) is overloaded or shortcircuited, the voltage may drop and result in the outputs being turned OFF. As a
countermeasure for such problems, external safety measures must be provided to
ensure safety in the system.
• External safety measures must also be taken to ensure safety in the event of
unexpected operation when connecting or disconnecting the connectors of the
CJ1W-MCH72.
!Caution User programs written to the CJ1W-MCH72 will not be automatically backed up in the
CJ1W-MCH72 flash memory (flash memory function).
!Caution Tighten the screws on the terminal block of the Power Supply Unit to the torque
specified in this manual. Loose screws may result in burning or malfunction.
!Caution When positioning to a position determined using the teaching function, set the position
designation setting in the positioning sequence to absolute positioning. If it is set to
relative positioning, positioning will be performed to a position other than the one
obtained with the teaching function.
!Caution Execute online edit only after confirming that no adverse effects will be caused by
extending the cycle time. Otherwise, the input signals may not be readable.
!Caution Confirm the safety of the destination node before transferring a program to the node or
changing the contents of I/O memory. Doing either of these without confirming safety
may result in injury.
!Caution Do not save data into the flash memory during memory operation or while the motor is
running. Otherwise, unexpected operation may be caused.
4 Operating environment precautions
!Caution Do not operate the control system in the following locations:
• Locations subject to direct sunlight.
• Locations subject to temperatures or humidity outside the range specified in the
specifications.
• Locations subject to condensation as the result of severe changes in temperature.
• Locations subject to corrosive or flammable gases.
• Locations subject to dust (especially iron dust) or salts.
• Locations subject to exposure to water, oil, or chemicals.
• Locations subject to shock or vibration.
viii
!Caution Take appropriate and sufficient countermeasures when installing systems in the
following locations:
• Locations subject to static electricity or other forms of noise.
• Locations subject to strong electromagnetic fields.
Application precautions 5
• Locations subject to possible exposure to radioactivity.
• Locations close to power supplies.
!Caution The operating environment of the PLC System can have a large effect on the longevity
and reliability of the system. Improper operating environments can lead to malfunction,
failure, and other unforeseeable problems with the PLC System. Be sure that the
operating environment is within the specified conditions at installation and remains
within the specified conditions during the life of the system.
5 Application precautions
!WARNING Do not start the system until you check that the axes are present and of the correct
type. The numbers of the axis will change if MECHATROLINK-II network errors occur
during start-up or if the MECHATROLINK-II network configuration changes.
!WARNING Check the user program for proper execution before actually running it in the Unit. Not
checking the program may result in an unexpected operation.
!WARNING Observe the following precautions when using the CJ1W-MCH72 or the PLC. Failure to
abide by the following precautions could lead to serious or possibly fatal injury. Always
heed these precautions.
• Always connect to a ground of 100 Ω or less when installing the Units. Not
connecting to a ground of 100 Ω or less may result in electric shock.
• Always turn OFF the power supply to the PLC before attempting any of the
following. Not turning OFF the power supply may result in malfunction or electric
shock.
- Mounting or dismounting Power Supply Units, I/O Units, CPU Units, Memory
Cassettes, or any other Units.
- Assembling the Units.
- Setting DIP switches or rotary switches.
- Connecting cables or wiring the system.
- Connecting or disconnecting the connectors.
!Caution Be sure that all mounting screws, terminal screws, and cable connector screws are
tightened to the torque specified in this manual. Incorrect tightening torque may result
in malfunction.
!Caution Wire correctly. Incorrect wiring may result in burning.
!Caution Mount the Unit only after checking the terminal block completely.
!Caution Resume operation only after transferring to the new CJ1W-MCH72 Unit the contents of
the VR and table memory required for operation. Not doing so may result in an
unexpected operation.
!Caution When replacing parts, be sure to confirm that the rating of a new part is correct. Not
doing so may result in malfunction or burning.
!Caution Use the dedicated connecting cables specified in operation manuals to connect the
Units. Using commercially available RS-232C computer cables may cause failures in
external devices or the Unit.
!Caution Outputs may remain on due to a malfunction in the built-in transistor outputs or other
internal circuits. As a countermeasure for such problems, external safety measures
must be provided to ensure the safety of the system.
!Caution Failure to abide by the following precautions may lead to faulty operation of the PLC,
the CJ1W-MCH72 or the system, or could damage the PLC or CJ1W-MCH72. Always
heed these precautions.
ix
Application precautions 5
• Fail-safe measures must be taken by the customer to ensure safety in the event of
incorrect, missing, or abnormal signals caused by broken signal lines, momentary
power interruptions, or other causes.
• Interlock circuits, limit circuits, and similar safety measures in external circuits (i.e.,
not in the Programmable Controller) must be provided by the customer.
• Install external breakers and take other safety measures against short-circuiting in
external wiring. Insufficient safety measures against short-circuiting may result in
burning.
• Install the PLC Unit as far as possible from sources of strong harmonic noise.
• Lock the sliders securely until they click into place when connecting the Power
Supply Unit, CPU Unit, I/O Units, Special I/O Units, or CPU Bus Units. Functions
may not work correctly if the sliders are not locked properly.
• Always attach the End Cover provided with the CPU Unit to the Unit on the right end
of the PLC. The CJ-series PLC will not operate properly if the End Cover is not
attached.
• Always use the power supply voltages specified in the operation manuals. An
incorrect voltage may result in malfunction or burning.
• Take appropriate measures to ensure that the specified power with the rated
voltage and frequency is supplied in places where the power supply is unstable. An
incorrect power supply may result in malfunction.
• Use crimp terminals for wiring. Do not connect bare stranded wires directly to
terminals. Connection of bare stranded wires may result in burning.
• Leave the label attached to the Unit when wiring. Removing the label may result in
malfunction if foreign matter enters the Unit.
• Remove the label after the completion of wiring to ensure proper heat dissipation.
Leaving the label attached may result in malfunction.
• Do not apply voltages to the Input Units in excess of the rated input voltage. Excess
voltages may result in burning.
• Do not apply voltages or connect loads to the Output Units in excess of the
maximum switching capacity. Excess voltage or loads may result in burning.
• Check the user program for proper execution before actually running it on the Unit.
Not checking the program may result in an unexpected operation.
• Be sure that the terminal blocks, Memory Units, expansion cables, and other items
with locking devices are properly locked into place. Improper locking may result in
malfunction.
• Double-check all wiring and switch settings before turning ON the power supply.
Incorrect wiring may result in burning.
• Disconnect the LR and GR terminals when performing insulation resistance or
withstand voltage tests. Not disconnecting the functional ground terminal may result
in burning.
!Caution Confirm that no adverse effect will occur in the system before attempting any of the
following. Not doing so may result in an unexpected operation.
• Changing the operating mode of the PLC (including the operating mode at power
up).
• Force-setting/force-resetting any bit in memory.
• Changing the present value of any word or any set value in memory.
!Caution Do not pull on the cables or bend the cables beyond their natural limit. Doing either of
these may break the cables.
!Caution Do not place objects on top of the cables or other wiring lines. Doing so may break the
cables.
!Caution Resume operation only after transferring the system parameter data to the CJ1W-
MCH72 and saving the data to flash memory. Not doing so may result in an unexpected
operation.
!Caution Confirm that set parameters and data operate properly.
!Caution Check the pin numbers before wiring the connectors.
x
Conformance to EC Directives 6
!Caution Perform wiring according to specified procedures.
!Caution Before touching a Unit, be sure to first touch a grounded metallic object in order to
discharge any static build-up. Not doing so may result in malfunction or damage.
!Caution Do not drop the Unit or subject it to abnormal shock or vibration.
!Caution Confirm the safety of the destination node before transferring a program to the node or
changing the contents of I/O memory. Doing either of these without confirming safety
may result in injury.
6 Conformance to EC Directives
6-1 Applicable directives
•EMC Directives
6-2 Concepts
OMRON devices that comply with EC Directives also conform to the related
EMC standards so that they can be more easily built into other devices or
machines. The actual products have been checked for conformity to EMC
standards (see the following note). Whether the products conform to the
standards in the system used by the customer, however, must be checked by
the customer.
EMC-related performance of the OMRON devices that comply with EC
Directives will vary depending on the configuration, wiring, and other
conditions of the equipment or control panel in which the OMRON devices are
installed. The customer must, therefore, perform final checks to confirm that
devices and the overall machine conform to EMC standards.
Note Applicable EMC (Electromagnetic Compatibility) standards are as follows:
• EMS (Electromagnetic Susceptibility): EN61000-6-2
• EMI (Electromagnetic Interference): EN61000-6-4
(Radiated emission: 10-m regulations)
6-3 Conformance to EC Directives
The CJ1W-MCH72 complies with EC Directives. To ensure that the machine
or device in which a CJ1W-MCH72 is used complies with EC Directives, the
CJ1W-MCH72 must be installed as follows:
1 The CJ1W-MCH72 must be installed within a control panel.
2 Reinforced insulation or double insulation must be used for the DC power
supplies used for the communications and I/O power supplies.
3 Units complying with EC Directives also conform to the Common Emission
Standard (EN61000-6-4). With regard to the radiated emission (10-m
regulations), countermeasures will vary depending on the devices
connected to the control panel, wiring, the configuration of the system, and
other conditions. The customer must, therefore, perform final checks to
confirm that devices and the overall machine conform to EC Directives.
xi
Conformance to EC Directives 6
6-4 Installation within Control Panel
Unnecessary clearance in cable inlet or outlet ports, operation panel mounting
holes, or in the control panel door may cause electromagnetic wave leakage
or interference. In this case, the product may fail to meet EC Directives. In
order to prevent such interference, fill clearances in the control panel with
conductive packing. (In places where conductive packing comes in contact
with the control panel, ensure electrical conductivity by removing the paint
coating or masking these parts when painting.)
xii
Overview Section 1-1
SECTION 1
Introduction
1-1 Overview
The CJ1W-MCH72 is a Trajexia-style motion control unit that can be
connected to a CJ1-series PLC. It acts as an interface between PLC systems
and Trajexia-style motion control systems.
Trajexia is the OMRON motion platform that offers you the performance and
the ease of use of a dedicated motion system. It maximum flexibility and
scalability. At the heart of Trajexia lies the TJ1 multi-tasking motion
coordinator. Powered by a 32-bit DSP, it can do motion tasks such as e-cam,
e-gearbox, registration control and interpolation, all using simple motion
commands.
The CJ1W-MCH72 has the following features:
• A MECHATROLINK-II connection for a MECHATROLINK-II network with
up to 30 axes. The motion cycle time is selectable: 0.5 ms, 1 ms, 2 ms or 4
ms.
• An Encoder Interface connection. It supports the main absolute encoder
protocols allowing the connection of an external encoder to the system.
• The possibility to exchange analogue and digital input and output data with
the PLC CPU.
• A wide choice of rotary, linear and direct-drive servos as well as Inverters
are available to fit your needs in compactness, performance and reliability.
The Inverters connected to the MECHATROLINK-II are driven at the same
update cycle time as the Servo Drivers.
Note The Trajexia system supports 3 kinds of MECHATROLINK-II slaves: Servo Drivers,
Inverters and I/Os.
The CJ1W-MCH72 only supports 2 kinds of MECHATROLINK-II slaves: Servo Drivers
and Inverters. It does not support I/Os.
1
System philosophy Section 1-2
r
1-2 System philosophy
CJ1W-MCH72
Program Buffer
Buffer &
Buffer &
profile
profile
gererator
gererator
AXIS CONTROL LOOP
Position
Position
Loop
Loop
AXIS TYPE
AXIS TYPE
AXIS TYPE
ML
BASIC PROGRAMS
Process 1
Process 2
Process 3
…
Process 14
Comms
I/O
BUILT-IN TJ1-PLC interface
Servo Driver
Position
Position
Loop
Loop
Speed Loop
Speed Loop
ENC
Torque
Torque
Loop
Loop
ENC
MOTOR
The system philosophy is centred around the relationship between:
•System architecture
•Cycle time
• Program control and multi-tasking
• Motion sequence and axes
• Motion buffers
All othe
Servo
Drivers
A clear understanding of the relationship between these concepts is
necessary to obtain the best results for the Trajexia system.
1-2-1 Glossary
1-2-1-1 Motion sequence
The Motion Sequence is responsible for controlling the position of the axes.
1-2-1-2 Servo period
Defines the frequency at which the Motion Sequence is executed. The servo
period must be set according to the configuration of the physical axes. The
available settings are 0.5 ms, 1 ms, 2 ms or 4 ms.
1-2-1-3 Cycle time
Is the time needed to execute one complete cycle of operations in the CJ1WMCH72. The cycle time is divided in 4 time slices of equal time length, called
"CPU Tasks". The cycle time is 1ms if SERVO_PERIOD = 0.5 ms or
SERVO_PERIOD = 1 ms, 2 ms if the SERVO_PERIOD = 2 ms and 4 ms if the
SERVO_PERIOD = 4 ms
2
System philosophy Section 1-2
1-2-1-4 CPU tasks
The operations executed in each CPU task are:
CPU task Operation
First CPU task Motion Sequence
Low priority process
Second CPU task High priority process
Third CPU task Motion Sequence (only if SERVO_PERIOD = 0.5 ms)
LED Update
High priority process
Fourth CPU task External Communications
1-2-1-5 Program
A program is a piece of BASIC code.
1-2-1-6 Process
Is a program in execution with a certain priority assigned. Process 0 to 12 are
Low priority processes and Process 13 and 14 are High priority processes.
First the process priority, High or Low, and then the process number, from high
to low, will define to which CPU task the process will be assigned.
3
Motion control concepts Section 1-3
1-3 Motion control concepts
The CJ1W-MCH72 offers these types of positioning control operations:
1 Point-to-Point (PTP) control
2 Continuous Path (CP) control
3 Electronic Gearing (EG) control.
This section introduces some of the commands and parameters used in the
BASIC programming of the motion control application.
Coordinate system
Positioning operations performed by the CJ1W-MCH72 are based on an axis
coordinate system. The CJ1W-MCH72 converts the position data from either
the connected Servo Driver or the connected encoder into an internal absolute
coordinate system.
The engineering unit that specifies the distances of travelling can be freely
defined for each axis separately. The conversion is performed through the use
of the unit conversion factor, which is defined by the UNITS axis parameter.
The origin point of the coordinate system can be determined using the
DEFPOS command. This command re-defines the current position to zero or
any other value.
1-3-1 PTP control
MOVEABS(30)
MOVE(60)
MOVEABS(50)
MOVE(50)
MOVE(30)
0
50 100
A
A move is defined in either absolute or relative terms. An absolute move takes
the axis (A) to a specific predefined position with respect to the origin point. A
relative move takes the axis from the current position to a position that is
defined relative to this current position. The figure shows an example of
relative (command MOVE) and absolute (command MOVEABS) linear moves.
In point-to-point positioning, each axis is moved independently of the other
axis. The CJ1W-MCH72 supports the following operations:
• Relative move
• Absolute move
• Continuous move forward
• Continuous move reverse.
4
Motion control concepts Section 1-3
1-3-1-1 Relative and absolute moves
50
B
0
50
MOVEABS(100) AXIS(0)
MOVEABS(50) AXIS(1)
100
A
To move a single axis either the command MOVE for a relative move or the
command MOVEABS for an absolute move is used. Each axis has its own
move characteristics, which are defined by the axis parameters.
Suppose a control program is executed to move from the origin to an axis no.
0 (A) coordinate of 100 and axis no. 1 (B) coordinate of 50. If the speed
parameter is set to be the same for both axes and the acceleration and
deceleration rate are set sufficiently high, the movements for axis 0 and axis 1
will be as shown in the figure.
At start, both the axis 0 and axis 1 moves to a coordinate of 50 over the same
duration of time. At this point, axis 1 stops and axis 0 continues to move to a
coordinate of 100.
The move of a certain axis is determined by the axis parameters. Some
relevant parameters are:
/i
Parameter Description
UNITS Unit conversion factor
ACCEL Acceleration rate of an axis in units/s
DECEL Deceleration rate of an axis in units/s
2
2
SPEED Demand speed of an axis in units/s
Defining moves
B
ACCEL=10
10
0
123 456
DECEL=10
SPEED=10
MOVE(40)
A
5
Motion control concepts Section 1-3
The speed profile in this figure shows a simple MOVE operation. Axis A is the
time, axis B is the speed. The UNITS parameter for this axis has been defined
for example as meters. The required maximum speed has been set to 10 m/s.
In order to reach this speed in one second and also to decelerate to zero
speed again in one second, both the acceleration as the deceleration rate
have been set to 10 m/s
travelled during the acceleration, constant speed and deceleration segments.
Suppose the distance moved by the MOVE command is 40 m, the speed
profile is given by the figure.
2
. The total distance travelled is the sum of distances
B
ACCEL=5
DECEL=10
SPEED=10
MOVE(40)
010123 456
A
The two speed profiles in these figures show the same movement with an
acceleration time respectively a deceleration time of 2 seconds. Again, Axis A
is the time, axis B is the speed.
B
ACCEL=10
DECEL=5
SPEED=10
MOVE(40)
010123 456
Move calculations
The following equations are used to calculate the total time for the motion of
the axes.
• The moved distance for the MOVE command is D.
• The demand speed is V.
• The acceleration rate is a.
• The deceleration rate is d.
A
/i
Acceleration time =
Acceleration distance =
Deceleration time =
6
Motion control concepts Section 1-3
Deceleration distance =
Constant speed distance =
Total time =
1-3-1-2 Continuous moves
The FORWARD and REVERSE commands can be used to start a continuous
movement with constant speed on a certain axis. The FORWARD command
moves the axis in positive direction and the REVERSE command in negative
direction. For these commands also the axis parameters ACCEL and SPEED
apply to specify the acceleration rate and demand speed.
Both movements can be cancelled by using either the CANCEL or
RAPIDSTOP command. The CANCEL command cancels the move for one
axis and RAPIDSTOP cancels moves on all axes. The deceleration rate is set
by DECEL.
1-3-2 CP control
Continuous Path control enables to control a specified path between the start
and end position of a movement for one or multiple axes. The CJ1W-MCH72
supports the following operations:
• Linear interpolation
• Circular interpolation
•CAM control.
1-3-2-1 Linear interpolation
2
1
3
B
A
7
Motion control concepts Section 1-3
In applications it can be required for a set of motors to perform a move
operation from one position to another in a straight line. Linearly interpolated
moves can take place among several axes. The commands MOVE and
MOVEABS are also used for the linear interpolation. In this case the
commands will have multiple arguments to specify the relative or absolute
move for each axis.
Consider the three axis move in a 3-dimensional plane in the figure. It
corresponds to the MOVE(50,50,50) command. The speed profile of the
motion along the path is given in the diagram. The three parameters SPEED,
ACCEL and DECEL that determine the multi axis movement are taken from
the corresponding parameters of the base axis. The MOVE command
computes the various components of speed demand per axis.
A is the time axis, B is the speed axis.
1-3-2-2 Circular interpolation
50
1-3-2-3 CAM control
-50
It may be required that a tool travels from the starting point to the end point in
an arc of a circle. In this instance the motion of two axes is related via a
circular interpolated move using the MOVECIRC command.
Consider the diagram in the figure. It corresponds to the MOVECIRC(-100,0,-
50,0,0) command. The centre point and desired end point of the trajectory
relative to the start point and the direction of movement are specified. The
MOVECIRC command computes the radius and the angle of rotation. Like the
linearly interpolated MOVE command, the ACCEL, DECEL and SPEED
variables associated with the base axis determine the speed profile along the
circular move.
050
B
A
8
Motion control concepts Section 1-3
Additional to the standard move profiles the CJ1W-MCH72 also provides a
way to define a position profile for the axis to move. The CAM command
moves an axis according to position values stored in the CJ1W-MCH72 Table
array. The speed of travelling through the profile is determined by the axis
parameters of the axis.
The figure corresponds to the command CAM(0,99,100,20). A is the time axis,
B is the position axis.
1-3-3 EG control
Electronic Gearing control allows you to create a direct gearbox link or a linked
move between two axes. The MC Unit supports the following operations.
• Electronic gearbox
•Linked CAM
• Linked move
• Adding axes
1-3-3-1 Electronic gearbox
B
2:1
1:1
1:2
A
The CJ1W-MCH72 is able to have a gearbox link from one axis to another as if
there is a physical gearbox connecting them. This can be done using the
CONNECT command in the program. In the command the ratio and the axis to
link to are specified.
In the figure, A is the Master axis, and B is the CONNECT axis.
/i
Axes Ratio CONNECT command
0 1
1:1 CONNECT(1,0) AXIS(1)
2:1 CONNECT(2,0) AXIS(1)
1:2 CONNECT(0.5,0) AXIS(1)
9
Motion control concepts Section 1-3
1-3-3-2 Linked CAM control
B
A
Next to the standard CAM profiling tool the CJ1W-MCH72 also provides a tool
to link the CAM profile to another axis. The command to create the link is
called CAMBOX. The travelling speed through the profile is not determined by
the axis parameters of the axis but by the position of the linked axis. This is
like connecting two axes through a cam.
In the figure, A is the Master axis (0) position, and B is the CAMBOX Axis (1)
position.
1-3-3-3 Linked move
B
DC
E
A
The MOVELINK command provides a way to link a specified move to a
master axis. The move is divided into an acceleration, deceleration and
constant speed part and they are specified in master link distances. This can
be particularly useful for synchronizing two axes for a fixed period.
The labels in the figure are:
A Time axis.
B Speed axis.
C Master axis (1).
D Synchronized.
E MOVELINK axis (0).
10
Motion control concepts Section 1-3
1-3-3-4 Adding axes
B
B
B
BASE(0)
ADDAX(2)
FORWARD
MOVE(100) AXIS(2)
MOVE(-60) AXIS(2)
A
A
It is very useful to be able to add all movements of one axis to another. One
possible application is for instance changing the offset between two axes
linked by an electronic gearbox. The CJ1W-MCH72 provides this possibility by
using the ADDAX command. The movements of the linked axis will consists of
all movements of the actual axis plus the additional movements of the master
axis.
In the figure, A is the time axis and B is the speed axis.
1-3-4 Other operations
1-3-4-1 Cancelling moves
In normal operation or in case of emergency it can be necessary to cancel the
current movement from the buffers. When the CANCEL or RAPIDSTOP
commands are given, the selected axis respectively all axes will cancel their
current move.
1-3-4-2 Origin search
The encoder feedback for controlling the position of the motor is incremental.
This means that all movement must be defined with respect to an origin point.
The DATUM command is used to set up a procedure whereby the CJ1WMCH72 goes through a sequence and searches for the origin based on digital
inputs and/or Z-marker from the encoder signal.
A
11
Motion control concepts Section 1-3
1-3-4-3 Print registration
The CJ1W-MCH72 can capture the position of an axis in a register when an
event occurs. The event is referred to as the print registration input. On the
rising or falling edge of an input signal, which is either the Z-marker or an
input, the CJ1W-MCH72 captures the position of an axis in hardware. This
position can then be used to correct possible error between the actual position
and the desired position. The print registration is set up by using the REGIST
command.
The position is captured in hardware, and therefore there is no software
overhead and no interrupt service routines, eliminating the need to deal with
the associated timing issues.
1-3-4-4 Merging moves
1-3-4-5 Jogging
B
MERGE=0
A
B
MERGE=1
A
If the MERGE axis parameter is set to 1, a movement is always followed by a
subsequent movement without stopping. The figures show the transitions of
two moves with MERGE value 0 and value 1.
In the figure, A is the time axis and B is the speed axis.
Jogging moves the axes at a constant speed forward or reverse by manual
operation of the digital inputs. Different speeds are also selectable by input.
Refer to the FWD_JOG, REV_JOG and FAST _JOG axis parameters.
12
Servo system principles Section 1-4
1-4 Servo system principles
The servo system used by and the internal operation of the CJ1W-MCH72 are
briefly described in this section.
1-4-1 Semi-closed loop system
The servo system of the CJ1W-MCH72 uses a semi-closed or inferred closed
loop system. This system detects actual machine movements by the rotation
of the motor in relation to a target value. It calculates the error between the
target value and actual movement, and reduces the error through feedback.
1-4-2 Internal operation of the CJ1W-MCH72
AB
C
2
1
D
E
3
F
G
4
I
H
J
Inferred closed loop systems occupy the mainstream in modern servo systems
applied to positioning devices for industrial applications. The figure shows the
basic principle of the servo system as used in the CJ1W-MCH72.
1 The CJ1W-MCH72 performs actual position control. The main input of the
controller is the Following Error, which is the calculated difference between
the demand position and the actual measured position.
2 The Position Controller calculates the required speed reference output
determined by the Following Error and possibly the demanded position and
the measured position. The speed reference is provided to the Servo
Driver.
3 The Servo Driver controls the rotational speed of the servo motor
corresponding to the speed reference. The rotational speed is proportional
to the speed reference.
4 The rotary encoder generates the feedback pulses for both the speed
feedback within the Servo Driver speed loop and the position feedback
within the CJ1W-MCH72 position loop.
The labels in the figure are:
A CJ1W-MCH72.
B Servo system.
C Demand position.
D Position control.
E Speed reference.
F Speed control.
G Motor.
H Encoder.
I Measured speed.
J Measured position.
13
Servo system principles Section 1-4
1-4-3 Motion control algorithm
The servo system controls the motor by continuously adjusting the speed
reference to the Servo Driver. The speed reference is calculated by the motion
control algorithm of the CJ1W-MCH72, which is explained in this section.
∑
K
vff
K
p
AB C
∑
K
i
∆
K
d
∆
K
ov
D
The motion control algorithm uses the demand position (A), the measured
position (D) and the Following Error (B) to determine the speed reference. The
Following Error is the difference between the demanded and measured
position. The demand position, the measured position and the Following Error
are represented by the axis parameters MPOS, DPOS and FE. Five gain
values have been implemented for the user to be able to configure the correct
control operation for each application.
C is the output signal.
• Proportional gain
The proportional gain K
Following Error E.
O
= Kp · E
p
All practical systems use proportional gain. For many just using this gain
parameter alone is sufficient. The proportional gain axis parameter is called
P_GAIN.
• Integral gain
The integral gain K
the Following Errors that have occurred during the system operation.
O
= Ki · ΣE
i
Integral gain can cause overshoot and so is usually used only on systems
working at constant speed or with slow accelerations. The integral gain axis
parameter is called I_GAIN.
• Derivative gain
The derivative gain K
change in the Following Error E and speeds up the response to changes in
error while maintaining the same relative stability.
O
= Kd · ∆E
d
Derivative gain may create a smoother response. High values may lead to
oscillation. The derivative gain axis parameter is called D_GAIN.
• Output speed gain
The output speed gain K
the change in the measured position P
O
= Kov · ∆P
ov
m
creates an output Op that is proportional to the
p
creates an output Oi that is proportional to the sum of
i
produces an output Od that is proportional to the
d
produces an output Oov that is proportional to
ov
and increases system damping.
m
14
Servo system principles Section 1-4
The output speed gain can be useful for smoothing motions but will
generate high Following Errors. The output speed gain axis parameter is
called OV_GAIN.
• Speed feed forward gain
The speed feedforward gain K
proportional to the change in demand position P
Following Error at high speed.
O
= K
vff
· ∆P
d
vff
The parameter can be set to minimise the Following Error at a constant
machine speed after other gains have been set. The speed feed forward
gain axis parameter is called VFF_GAIN.
The default settings are given in the table along with the resulting profiles.
Fractional values are allowed for gain settings.
/i
Gain Default value
Proportional gain 0.1
Integral gain 0.0
Derivative gain 0.0
Output speed gain 0.0
produces an output O
vff
and minimizes the
d
that is
vff
Speed feedforward gain 0.0
15
Trajexia system architecture Section 1-5
1-5 Trajexia system architecture
The system architecture of the Trajexia is dependant upon these
concepts:
• Program control
• Motion Sequence
• Motion buffers
• Communication
•Peripherals
These concepts depend upon the value set in the SERVO_PERIOD
parameter. The relationship between the value of SERVO_PERIOD and the
different concepts of the system architecture are describes as follows.
1-5-1 Program control
Programs make the system work in a defined way. The programs are written in
a language similar to BASIC and control the application of the axes and
modules. 14 Programs can be executed in parallel. The programs can be set
to run at system power-up, started and stopped from other programs and
executed from Trajexia Studio.
Programs execute commands to move the axes, control inputs and outputs
and make communication via BASIC commands.
1-5-2 Motion sequence
The motion sequence controls the position of all 32 axes with the actions as
follows:
• Reading the Motion buffer
• Reading the current Measured Position (MPOS)
• Calculating the next Demanded Position (DPOS)
• Executing the Position loop
• Sending the Axis reference
• Error handling
1-5-3 Motion buffers
Motion buffers are the link between the BASIC commands and the Axis control
loop. When a BASIC motion command is executed, the command is stored in
one of the buffers. During the next motion sequence, the profile generator
executes the movement according to the information in the buffer.
When the movement is finished, the motion command is removed from the
buffer.
1-5-4 Communication
The CJ1W-MCH72 can exchange data with memory areas in the PLC. This
enables the CJ1W-MCH72 to use the inputs and outputs connected to the
PLC. Also, programs in the CJ1W-MCH72 and PLC programs can exchange
control and status data.
For more information on communication and data exchange, refer to chapter
3.
1-5-5 Peripherals
16
All inputs and outputs are used with the set of parameters (IN, OP, AIN,
AOUT). The inputs and outputs are automatically detected and mapped in
Trajexia. Inverters are considered a peripheral device and have a set of
BASIC commands to control them.
Cycle time Section 1-6
1-6 Cycle time
All processes in the Trajexia system are based on the cycle time. The cycle
time is divided into four CPU tasks:
•250 µs time intervals for a SERVO_PERIOD of 0.5 and 1.0 ms
250µs
1
2
Cycle time = 1ms
3
4
•500 µs time intervals for a SERVO_PERIOD of 2.0 ms
500 µs
1
2
Cycle time = 2 ms
3
4
• 1 ms time intervals for a SERVO_PERIOD of 4.0 ms
1 ms
1
2
Cycle time = 4 ms
3
4
The processes that can be carried out in each time interval depends on the
SERVO_PERIOD that is set.
The operations executed in each CPU task are:
CPU task Operation
First CPU task Motion Sequence
Low priority process
Second CPU task High priority process
Note The Motion sequence execution depends on setting of the SERVO_PERIOD parame-
1-6-1 Servo period
Third CPU task Motion Sequence (only if SERVO_PERIOD=0.5ms)
LED Update.
High priority process
Fourth CPU task External Communications
ter.
The SERVO_PERIOD can be set at 0.5, 1, 2 or 4 ms. The processes that take
place within the cycle time depend on the setting of the SERVO_PERIOD
parameter. The SERVO_PERIOD parameter is a Trajexia parameter that must
be set according to the system configuration.
The factory setting is 1ms (SERVO_PERIOD=1000). A change is set only
after a restart of the CJ1W-MCH72.
17
Cycle time Section 1-6
Note Only the Sigma-III Servo Driver and the Sigma-V Servo Driver support the 0.5 ms trans-
mission cycle.
1-6-1-1 Servo period 0.5 ms
The SERVO_PERIOD has a value of 0.5ms and the motion sequence is
executed every 0.5ms.
1-6-1-2 Servo period 1 ms
CPU task 1
CPU task 2
CPU task 3
CPU task 4
CPU task 1
CPU task 2
CPU task 3
Motion sequence
Low priority task (0,1,2,3...)
High priority task (13,14)
Motion sequence
LED refresh
High priority task (13,14)
Communication
Motion sequence
Low priority task (0,1,2,3...)
High priority task (13,14)
LED refresh
High priority task (13,14)
1ms
1ms
The SERVO_PERIOD has a value of 1ms and the motion sequence is
executed every 1ms. As the motion sequence is not executed during CPU task
3, there is more time for the program execution. High priority programs run
faster.
1-6-1-3 Servo period 2 ms
The SERVO_PERIOD has a value of 2ms and the motion sequence is
executed every 2.0ms.
CPU task 4
CPU task 1
CPU task 2
CPU task 3
CPU task 4
Communication
Motion sequence
Low priority task (0,1,2,3...)
High priority task (13,14)
LED refresh
High priority task (13,14)
Communication
2ms
18
Cycle time Section 1-6
1-6-1-4 Servo period 4 ms
The SERVO_PERIOD has a value of 4ms and the motion sequence is
executed every 4.0ms.
1-6-1-5 Servo period rules
The number of axes and MECHATROLINK-II slaves in the Trajexia system
determines the value of the SERVO_PERIOD system parameter.
There are 2 types of MECHATROLINK-II slaves that are supported by the
CJ1W-MCH72 units:
• Servo Drivers
• Inverters
You should comply with the most restrictive rules when you set the
SERVO_PERIOD parameter. An incorrect value of the SERVO_PERIOD
parameter results in an incorrect detection of the MECHATROLINK-II slaves.
The most restrictive rules are given in the tables below. For each unit the table
lists the maximum number of slaves the unit can control at the given
SERVO_PERIOD setting.
/i
CPU task 1
CPU task 2
CPU task 3
CPU task 4
Motion sequence
Low priority task (0,1,2,3...)
High priority task (13,14)
LED refresh
High priority task (13,14)
Communication
The CJ1W-MCH72 considers Servo Drivers as axes.
The CJ1W-MCH72 does not consider Inverters as axes.
SERVO_PERIOD Total number
of axes
Number of
MECHATROLINK-II
stations
axes inverters
4ms
Total number of
MECHATROLINK-II
stations
0.5 ms 8 4 4 4
1.0 ms 16 8 8 8
2.0 ms 16 16 8 16
4.0 ms 32 30 8 30
19
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