Omron SYSMAC C200H-NC111 User manual

Cat. No. W137-E1-04
Position Control Unit
SYSMAC
C200H-NC111

SYSMAC C200H-NC111
Position Control Unit
Operation Manual
Revised September 2003

iv

!
!
!
v
Notice:
OMRON products are manufactured for use according to proper procedures by a qualified operator
and only for the purposes described in this manual.
The following conventions are used to indicate and classify precautions in this manual. Always heed
the information provided with them. Failure to heed precautions can result in injury to people or dam-
age to property.
DANGER Indicates an imminently hazardous situation which, if not avoided, will result in death or
serious injury.
WARNING Indicates a potentially hazardous situation which, if not avoided, could result in death or
serious injury.
Caution Indicates a potentially hazardous situation which, if not avoided, may result in minor or
moderate injury, or property damage.
OMRON Product References
All OMRON products are capitalized in this manual. The word “Unit” is also capitalized when it refers
to an OMRON product, regardless of whether or not it appears in the proper name of the product.
The abbreviation “Ch,” which appears in some displays and on some OMRON products, often means
“word” and is abbreviated “Wd” in documentation in this sense.
The abbreviation “PC” means Programmable Controller and is not used as an abbreviation for any-
thing else.
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.
1, 2, 3... 1. Indicates lists of one sort or another, such as procedures, checklists, etc.
OMRON, 1990
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 permis-
sion 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 informa-
tion contained in this publication.

vi

vii
TABLE OF CONTENTS
PRECAUTIONS xi. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1 Intended Audience xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 General Precautions xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Safety Precautions xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Operating Environment Precautions xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Application Precautions xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SECTION 1
Introduction 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–1 Features 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–2 Components 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–3 System Configuration 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–4 Control System Principles 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SECTION 2
Before Operation 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–1 Switch Settings 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2–2 Wiring 13.................................................................
2–3 Dimensions 24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SECTION 3
Operation 25. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–1 Operational Flow 26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–2 Output Pulses 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–3 Writing Data 28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–4 Data Configuration and Allocation 29. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–5 IR Area Data Format 32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–6 Flags and Other Input Data 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3–7 DM Area Allocation 33. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SECTION 4
Commands 43. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–1 Start 44. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–2 Origin Search 55. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–3 Origin Return 63. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–4 Release Prohibit 65. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–5 Read Error 68. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–6 Reset Origin 69. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–7 Teach 69.................................................................
4–8 Transfer Data 71. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–9 Manual Operations 78. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4–10 External Interrupt Commands 81. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

viii
SECTION 5
Programming Examples 91. . . . . . . . . . . . . . . . . . . . . . . . . .
5–1 Operation with Minimum Data: Displaying JOG Positions 92. . . . . . . . . . . . . . . . . . . . . . .
5–2 Positioning at Intervals: Using RESET ORIGIN 94. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–3 Feeding Selectively with START 96. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–4 Transfer Data from Other PC Areas 96. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–5 Transfer Data from External Switches 99. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–6 Using START to Carry Out Positioning Actions 101. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–7 Using Origin and Origin Proximity Signals 105. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–8 Using Zones to Control Jogging 106. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–9 Controlling an R88D-EP06 Servodriver 107. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5–10 Controlling a V-series Servodriver 110. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SECTION 6
Error Processing 111. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6–1 Alarms and Errors 112. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6–2 Outputs to the IR Area 112. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6–3 Alarm/Error Indicators 112. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6–4 Troubleshooting from the PC 112. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6–5 Basic Troubleshooting Chart 115. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6–6 Detection of Abnormal Pulse Outputs 116. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Appendices
A Alarm Code List 119. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
B Error Code List 123. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
C DM Area Allocations 127. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
D IR Area Allocations 133. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
E Specifications 137. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
F Standard Models 139. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Glossary 141. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Index 147. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Revision History 151. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ix
About this Manual:
The C200H–NC111 Position Control Unit is a Special I/O Unit for C200H PCs. It is designed to control
equipment positioning through pulse train outputs to a motor driver. The degree of movement is
based on the program installed into the PC and the external control inputs.
This manual covers the specifications and procedures necessary for installation and efficient opera-
tion. Before attempting to operate the C200H Position Control Unit, be sure to thoroughly familiarize
yourself with the information contained within this and any other relevant manuals.
Section 1 describes the basic features and components of the Position Control Unit. It also gives de-
tails on configurations for positioning control systems and their principles of operation.
Section 2 describes how to incorporate the Positioning Control Unit into a system. It provides infor-
mation on how to set switches so that the Unit provides the desired operating functions. It also gives
mounting and wiring information.
Section 3 gives details on the procedures for setting up and operating a positioning control system. It
includes information on PC operations (such as flags, zone settings, the range of output pulses, back-
lash compensation, etc.), data areas and data formats.
Section 4 outlines the thirteen commands available on the Positioning Control Unit. It describes each
command, how it works, the data required,and the data areas used. Examples are given (in timing
chart form) which show the status of the relevant inputs, outputs, bits, and flags during the execution
of the commands.
Section 5 provides programming examples which give practical illustrations of how the Positioning
Control Unit commands can be used to implement effective positioning control.
Section 6 explains various error and alarm conditions and the steps that can be taken to avoid and/or
prevent them.
Appendix A provides more detailed information on alarm codes, including the type of operations in
which the alarm may arise, the type of error, the alarm code, and the most probable cause.
Appendix B lists the error codes in numeric sequence and provides information on the cause of, and
remedy for, the existing problem.
Appendix C describes the functions that each of the different parts of the DM Area performs.
Appendix D describes the functions for which each of the different parts of the IR Area can be used.
Appendix E provides the performance and electrical specifications for the Positioning Control Unit.
Appendix F lists the models which are used with the Positioning Control Unit.
A comprehensive Glossary is provided which explains many of the terms and abbreviations com-
monly used when referring to Positioning Control Units and PC Systems.
WARNING Failure to read and understand the information provided in this manual may result in
personal injury or death, damage to the product, or product failure. Please read each
section in its entirety and be sure you understand the information provided in the section
and related sections before attempting any of the procedures or operations given.
!

xi
PRECAUTIONS
This section provides general precautions for using the Programmable Controller (PC), Position Control Unit (PCU), and
related devices.
The information contained in this section is important for the safe and reliable application of the Programmable Con-
troller and the Position Control Unit. You must read this section and understand the information contained before
attempting to set up or operate a PC system.
1 Intended Audience xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 General Precautions xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Safety Precautions xii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Operating Environment Precautions xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
5 Application Precautions xiii. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

!
!
!
5Safety Precautions
xii
1 Intended Audience
This manual is intended for the following personnel, who must also have knowl-
edge 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 programming and operating Position Con-
trol Unit. Be sure to read this manual before attempting to use the PCU and keep
this manual close at hand for reference during operation.
3 Safety Precautions
WARNING Never attempt to disassemble any Units while power is being supplied. Doing so
may result in serious electrical shock or electrocution.
WARNING Never touch any of the terminals while power is being supplied. Doing so may
result in serious electrical shock or electrocution.
WARNING Provide safety measures in external circuits (i.e., not in the Programmable
Controller), including the following items, to ensure safety in the system if an
abnormality occurs due to malfunction of the PC or another external factor
affecting the PC operation. Not doing so may result in serious accidents.
•Emergency stop circuits, interlock circuits, limit circuits, and similar safety
measures must be provided in external control circuits.
•The PC 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 coun-
termeasure for such errors, external safety measures must be provided to
ensure safety in the system.
•The PC 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 PC) is overloaded or
short-circuited, 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.

!
!
5Application Precautions
xiii
4 Operating Environment Precautions
Do not operate the control system in the following places.
•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 tempera-
ture.
•Locations subject to corrosive or flammable gases.
•Locations subject to dust (especially iron dust) or salts.
•Locations subject to shock or vibration.
•Locations subject to exposure to water, oil, or chemicals.
•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 electric fields or magnetic fields.
•Locations subject to possible exposure to radioactivity.
•Locations close to power supplies.
5 Application Precautions
Observe the following precautions when using the Position Control Unit (PCU)
and Programmable Controller (PC).
WARNING Failure to abide by the following precautions could lead to serious or possibly
fatal injury. Always heed these precautions.
•Always ground the system to 100 Ωor less when installing the system to pro-
tect against electrical shock.
•Always turn off the power supply to the PC before attempting any of the follow-
ing:
•Mounting or dismounting the Power Supply Unit, I/O Units, CPU Unit,
other Units, or Memory Casettes.
•Assembling the devices.
•Setting DIP switches or rotary switches.
•Wiring or connecting cables.
•Connecting or disconnecting the connectors.
Caution Failure to abide by the following precautions could lead to faulty operation of the
PC or the system or could damage the PC or PC Units. Always heed these pre-
cautions.
•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 must be provided
by the customer as external circuits.
•Install external breakers and take other safety measures against short-circuit-
ing in external wiring.
•Tighten the PC mounting screws, terminal block screws, and cable screws to
the torque specified in this manuals.
•Always use the power supply voltage specified in this manual.

5Application Precautions
xiv
•Take appropriate measures to ensure that the specified power with the rated
voltage and frequency is supplied. Be particularly careful in places where the
power supply is unstable.
•Use crimp terminals for wiring. Do not connect bare stranded wires directly to
terminals.
•Leave the dustproof labels affixed to the top of the Unit when wiring. After wir-
ing, remove the labels for proper heat radiation.
•Do not apply voltages to the Input Units in excess of the rated input voltage.
•Do not apply voltages or connect loads to the Output Units in excess of the
maximum switching capacity.
•Check the user program for proper execution before actually running it in the
Unit.
•Be sure that the terminal blocks, memory units, extension cables, and other
items with locking devices are properly locked.
•Double-check all the wiring before turning on the power supply.
•Disconnect the functional ground terminal when performing withstand voltage
tests.
•Confirm that no adverse effect will occur in the system before performing the
following operations:
•Changing the operating mode of the PC.
•Force-setting/resetting the relay contacts.
•Changing the present values or set values.
•Changing positioning data or parameters.
•Resume operation only after transferring to the new CPU Unit the contents of
the DM and HR Areas required for operation.
•Do not attempt to disassemble, repair, or modify any Units.
•Do not pull on or bend the cables beyond their natural limit. Doing so may break
the cables.
•Do not place heavy objects on top of the cables. Doing so may break the
cables.
•Resume operation only after saving in the Position Control Unit the parameters
and position data required for resuming operation.
•Be sure that the set parameters and data operate properly.
•Be sure to check the pin numbers before wiring the connectors.
•Perform wiring according to specified procedures.
•Before touching a Unit, be sure to first touch a grounded metallic object in order
to discharge any static build-up from your body. Not doing so may result in mal-
function or damage

1
SECTION 1
Introduction
The C200H-NC111 Position Control Unit is a Special I/O Unit that receives positioning commands either externally or
from a Programmable Controller (PC) and uses that data to output control voltages to a stepping motor driver or a ser-
vomotor driver.
This section describes the basic features and components of the Position Control Unit, as well as the basic configuration
and operating principles of positioning control systems. Be sure to read and study these sections carefully; an understand-
ing of the control system is essential for successful operation.
1–1 Features 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–2 Components 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–3 System Configuration 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–4 Control System Principles 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–4–1 Open-loop System 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1–4–2 Semi-closed-loop System 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2
1–1 Features
Applicable Motor DriversThe pulse train output can be easily connected to either of the following de-
vices:
1) Stepping motor driver
2) Servomotor driver designed for pulse train input
Number of Control Axes
and Controlling CapacityThe Position Control Unit is designed exclusively to control a single axis and
is capable of controlling speeds and positions through parameters recorded
in the DM area of the C200H PC.
Manual Operation Three commands enable manual positioning control: HIGH-SPEED JOG,
LOW-SPEED JOG, and INCH.
Data Transfer Positioning actions, speeds, and other data contained in the DM area or
other areas of the PC can be quickly transferred via a TRANSFER DATA
command. Control scale can thus be expanded to exceed the data capacity
of the Position Control Unit.
Establishing Position The TRANSFER DATA command can also be used to change the present
position to any target value, including 0 (origin), anytime the Position Control
Unit is not outputting pulses.
Teaching The present position can be written into the memory of the PC as positioning
data whenever pulses are not being output.
1–2 ComponentsIn addition to the front-panel components described on the following page,
there is a DIP switch located on the back panel. Pin settings for this switch,
which are described under 2–1 Switch Settings, determine certain aspects of
control system operation.
Components Section 1–2

3
Indicators
RUN: indicates operation
is in progress
CW: indicates controlled system
(motor) is revolving clockwise
CCW: indicates controlled system
(motor) is revolving counterclockwise
BUSY: indicates operation/transfer
is in progress
ALARM: blinks when an abnormality
has occurred
ERROR: lights when an error has oc-
curred
Setting switches
MACHINE No.
MODE
Allocates a unit number (0 to 9) to
the Position Control Unit
Not used
Connector
Used to connect the Position
Control Unit to a stepping mo-
tor driver or servomotor driver.
Attach the enclosed connector
to the proper cable.
When setting the switches, use a
screwdriver if necessary.
Do not apply an excessive force to the
switches.
Do not leave the switches halfway be-
tween two setting points or the Position
Control Unit may malfunction.
Before operating these switches, make
sure that power to the PC is off.
Indicators Position Control Unit indicators (LEDs) are used to quickly determine operat-
ing status. They are particularly valuable in initial system activation and de-
bugging, but can also be used to monitor and check Unit operation.
Indicator Color Function
Lit during normal operation. Goes out for errors.
Lit during output of CW (clockwise) pulses.
Lit during output of CCW (counterclockwise) pulses.
Lit during positioning or data transfer.
Flashing when a BCD error exists in initial data, speed
data, or positioning data updated with TRANSFER DATA.
Lit when an error has occurred causing operation to stop.
Green
Green
Green
Green
Red
Red
RUN
CW
CCW
BUSY
ALARM
(flashing)
ERROR
1–3 System Configuration
The basic system configuration is shown below. Position Control Unit outputs
are connected to a motor driver, either for a stepping motor or for a ser-
vomotor (either AC or DC) capable of receiving pulse train inputs. The Unit is
controlled by inputs from devices and/or a control panel. It, in turn, outputs
pulse trains and direction signals to control the motor driver.
System Configuration Section 1–3

4
The motor driver controls either a stepping motor or a servomotor, depending
on whether an open-loop or semiclosed-loop system is employed. (See 1–4
Control System Principles). The stepping motor (or servomotor) controls
some type of positioning device (such as a feed screw, for example). An in-
dependent power supply must be used. Some configurations also require an
Input Unit on the C200H PC to control the motor driver.
Maximum Number of
Special I/O Units per PC A maximum of 10 Special I/O Units, including Position Control Units,
High-Speed Counters, etc., can be mounted under the same PC, regardless
of whether they are on the CPU Rack, an Expansion I/O Rack, or a rack con-
taining a Remote I/O Slave Unit controlled by the PC. No more than four of
these can be mounted onto any one rack containing a Remote I/O Slave
Unit.
Mounting Location The Position Control Unit can be mounted to any but the 2 rightmost CPU
Rack slots. Mounting the Unit to either of these slots will prevent you from
mounting devices directly to the PC’s CPU. The back-panel DIP switch must
be set before the Unit is mounted. This switch is inaccessible on a mounted
Unit. (See 2–1 Switch Settings.)
Basic Configuration Although Unit operation can be indirectly controlled from a host computer,
Remote I/O Master Unit, or other control system or peripheral device, direct
control comes from the program of the PC or from connections to external
inputs (e.g., control panel switches). (A list of Position Control Unit inputs and
outputs can be found under I/O Circuits in 2–2 Wiring.) The following configu-
ration diagrams show only the positioning system itself. Refer to the operat-
ing manuals for other Omron control devices for details on extended control
system operation.
System Configuration Section 1–3

5
Control signal input switches
C200H PC Position Control Unit C200H-NC111
Input Unit
Stepping motor (or ser-
vomotor) driver control
signal line
Power supply Hand-held Programming
Console C200H-PRO27
Stepping motor driver
(or servomotor driver)
Operation panel
Operation switch
Stepping motor
(or servomotor)
1–4 Control System Principles
Control systems can be quite simple or relatively complex. The most basic is
an open-loop system, in which a particular operation is carried out, according
to programmed instructions, but in which adjustments are not made directly
by the PC. Instead, the open-loop system typically displays or prints out infor-
mation to assist a human operator in making any required adjustments. The
C200H-NC111 Position Control Unit can be used in an open-loop system in
conjunction with a stepping motor.
In a closed-loop system, on the other hand, the PC controls an external proc-
ess without human intervention. The servomotor provides direct feedback so
that actual values (of positions, speeds, and so on) are continuously adjusted
Control System Principles Section 1–4

6
to bring them more closely in line with target values. In some systems, the
digital feedback signals will be transmitted to a digital-to-analog converter to
complete the feedback loop, thereby permitting automated control of the
process.
A semiclosed-loop system is similar to a closed-loop system, except that
feedback is provided by a tachogenerator and a rotary encoder rather than
directly by the servomotor. If the C200H-NC111 Position Control Unit is used
with a servomotor, the servomotor driver must be able to handle digital sig-
nals, and there is no need for a D/A converter. In addition, the servomotor is
connected to a tachogenerator and a rotary encoder. The Unit can thus be
used in either an open-loop or a semiclosed-loop system.
Both open-loop and semiclosed-loop systems are described in more detail on
the following pages.
Control System Principles Section 1–4

7
Data Flow
PC
BUS
I/F
C200H PC
Position Control Unit C200H-NC111
Rotary encoder
Tachogenerator
Servomotor driver
Pulse train
Power
amplifier
Pulse
train
Stepping motor driver
I/O
interface
MPU
Memory
Pulse
gen-
erator
Magnetizing
distribution
circuit
Servomotor
(Positioning output)
PC
BUS
I/F
External
input
Stepping motor
Error counter Power amplifier
I/O connector
1–4–1 Open-loop System
In an open-loop system, the Position Control Unit outputs pulse trains as
specified by the PC program to control the angle of rotation of the motor. Be-
cause the Unit outputs pulse trains, it is generally used with a stepping motor.
The angle of rotation of a stepping motor can be controlled through the num-
ber of pulse signals supplied to the motor driver. The number of rotations of
the stepping motor is proportional to the number of pulses supplied by the
Unit, and the rotational speed of the stepping motor is proportional to the
Control System Principles Section 1–4

8
frequency of the pulse train.
Positioning pulse
1 2 n
Positioning output
Angle of
rotation
Angle of rotation
Simplified Positioning
System Design The following diagram and parameters illustrate a simplified positioning sys-
tem.
P
Stepping motor
Reduction gear Object being
positioned
M: Reduction ratio
P: Feed screw pitch (mm/revolution)
V: Feed velocity of object being positioned (mm/s)
θs: Stepping angle per pulse (degree/pulse)
N
M
V
Feed screw pitch
The positioning accuracy in mm/pulse is computed as follows:
Positioning accuracy = P/(pulses per revolution x M)
= P/((360/S) x M))
= (P x S)/(360 x M)
The required pulse frequency from the Unit in pulses per second is computed
as follows:
Pulse frequency = V/Positioning accuracy
= (360 x M x V)/(P x S)
And the required number of pulses to feed an object by a distance L in mm is
computed as follows:
Number of pulses = L/Positioning accuracy
= (360 x M x L)/(P x S)
1–4–2 Semi-closed-loop System
When the Position Control Unit is used in a semiclosed-loop system, the sys-
tem supplies feedback to compensate for any discrepancy between target
values and actual values in position or speed. This system detects motor ro-
Control System Principles Section 1–4