Mitsubishi Electric MELSEC Q Series User manual

MELSEC-Q Current Transformer Input Module
User's Manual
-Q68CT

1
SAFETY PRECAUTIONS
(Read these precautions before using this product.)
Before using this product, please read this manual and the relevant manuals carefully and pay full attention
to safety to handle the product correctly.
The precautions given in this manual are concerned with this product only. For the safety precautions of the
programmable controller system, refer to the user's manual for the CPU module used.
In this manual, the safety precautions are classified into two levels: " WARNING" and " CAUTION".
Under some circumstances, failure to observe the precautions given under " CAUTION" may lead to
serious consequences.
Observe the precautions of both levels because they are important for personal and system safety.
Make sure that the end users read this manual and then keep the manual in a safe place for future
reference.
[Design Precautions]
WARNING
●Do not write any data to the "system area" and "write-protect area" of the buffer memory in the
intelligent function module. Also, do not use any "use prohibited" signal as an output signal from the
CPU module to the intelligent function module. Doing so may cause malfunction of the programmable
controller system.
CAUTION
●Do not install the control lines or communication cables together with the main circuit lines or power
cables. Failure to do so may result in malfunction due to noise.
WARNING
CAUTION
Indicates that incorrect handling may cause hazardous conditions,
resulting in death or severe injury.
Indicates that incorrect handling may cause hazardous conditions,
resulting in minor or moderate injury or property damage.

2
[Installation Precautions]
[Wiring Precautions]
CAUTION
●Use the programmable controller in an environment that meets the general specifications in the user's
manual for the CPU module used. Failure to do so may result in electric shock, fire, malfunction, or
damage to or deterioration of the product.
●To mount the module, while pressing the module mounting lever located in the lower part of the
module, fully insert the module fixing projection(s) into the hole(s) in the base unit and press the
module until it snaps into place. Incorrect interconnection may cause malfunction, failure, or drop of
the module. When using the programmable controller in an environment of frequent vibrations, fix the
module with a screw.
●Tighten the screws within the specified torque range. Undertightening can cause drop of the screw,
short circuit, or malfunction. Overtightening can damage the screw and/or module, resulting in drop,
short circuit, or malfunction.
●Shut off the external power supply (all phases) used in the system before mounting or removing the
module. Failure to do so may result in damage to the product. A module can be replaced online (while
power is on) on any MELSECNET/H remote I/O station or in the system where a CPU module
supporting the online module change function is used. Note that there are restrictions on the modules
that can be replaced online, and each module has its predetermined replacement procedure. For
details, refer to the relevant chapter in this manual.
●Do not directly touch any conductive parts and electronic components of the module. Doing so can
cause malfunction or failure of the module.
WARNING
●After installation and wiring, attach the included terminal cover to the module before turning it on for
operation. Failure to do so may result in electric shock.
CAUTION
●Individually ground the FG terminal of the programmable controller with a ground resistance of 100
or less. Failure to do so may result in electric shock or malfunction.
●Tighten the terminal screws within the specified torque range. Undertightening can cause short circuit,
fire, or malfunction. Overtightening can damage the screw and/or module, resulting in drop, short
circuit, or malfunction.
●Prevent foreign matter such as dust or wire chips from entering the module. Such foreign matter can
cause a fire, failure, or malfunction.
●A protective film is attached to the top of the module to prevent foreign matter, such as wire chips,
from entering the module during wiring. Do not remove the film during wiring. Remove it for heat
dissipation before system operation.

3
[Startup and Maintenance Precautions]
[Disposal Precautions]
WARNING
●Do not touch any terminal while power is on. Doing so will cause electric shock or malfunction.
●Shut off the external power supply (all phases) used in the system before cleaning the module or
retightening the terminal screws or module fixing screws. Failure to do so may result in electric shock
or cause the module to fail or malfunction. Undertightening can cause drop of the screw, short circuit,
or malfunction. Overtightening can damage the screw and/or module, resulting in drop, short circuit,
or malfunction.
CAUTION
●Do not disassemble or modify the modules.
Doing so may cause failure, malfunction, injury, or a fire.
●Shut off the external power supply (all phases) used in the system before mounting or removing the
module. Failure to do so may cause the module to fail or malfunction. A module can be replaced
online (while power is on) on any MELSECNET/H remote I/O station or in the system where a CPU
module supporting the online module change function is used. Note that there are restrictions on the
modules that can be replaced online, and each module has its predetermined replacement procedure.
For details, refer to the relevant chapter in this manual.
●After the first use of the product, do not mount/remove the module to/from the base unit, and the
terminal block to/from the module more than 50 times (IEC 61131-2 compliant) respectively.
Exceeding the limit of 50 times may cause malfunction.
●Before handling the module, touch a grounded metal object to discharge the static electricity from the
human body. Failure to do so may cause the module to fail or malfunction.
CAUTION
●When disposing of this product, treat it as industrial waste.

4
CONDITIONS OF USE FOR THE PRODUCT
(1) Mitsubishi programmable controller ("the PRODUCT") shall be used in conditions;
i) where any problem, fault or failure occurring in the PRODUCT, if any, shall not lead to any major
or serious accident; and
ii) where the backup and fail-safe function are systematically or automatically provided outside of
the PRODUCT for the case of any problem, fault or failure occurring in the PRODUCT.
(2) The PRODUCT has been designed and manufactured for the purpose of being used in general
industries.
MITSUBISHI SHALL HAVE NO RESPONSIBILITY OR LIABILITY (INCLUDING, BUT NOT
LIMITED TO ANY AND ALL RESPONSIBILITY OR LIABILITY BASED ON CONTRACT,
WARRANTY, TORT, PRODUCT LIABILITY) FOR ANY INJURY OR DEATH TO PERSONS OR
LOSS OR DAMAGE TO PROPERTY CAUSED BY the PRODUCT THAT ARE OPERATED OR
USED IN APPLICATION NOT INTENDED OR EXCLUDED BY INSTRUCTIONS, PRECAUTIONS,
OR WARNING CONTAINED IN MITSUBISHI'S USER, INSTRUCTION AND/OR SAFETY
MANUALS, TECHNICAL BULLETINS AND GUIDELINES FOR the PRODUCT.
("Prohibited Application")
Prohibited Applications include, but not limited to, the use of the PRODUCT in;
• Nuclear Power Plants and any other power plants operated by Power companies, and/or any
other cases in which the public could be affected if any problem or fault occurs in the PRODUCT.
• Railway companies or Public service purposes, and/or any other cases in which establishment of
a special quality assurance system is required by the Purchaser or End User.
• Aircraft or Aerospace, Medical applications, Train equipment, transport equipment such as
Elevator and Escalator, Incineration and Fuel devices, Vehicles, Manned transportation,
Equipment for Recreation and Amusement, and Safety devices, handling of Nuclear or
Hazardous Materials or Chemicals, Mining and Drilling, and/or other applications where there is a
significant risk of injury to the public or property.
Notwithstanding the above, restrictions Mitsubishi may in its sole discretion, authorize use of the
PRODUCT in one or more of the Prohibited Applications, provided that the usage of the PRODUCT
is limited only for the specific applications agreed to by Mitsubishi and provided further that no
special quality assurance or fail-safe, redundant or other safety features which exceed the general
specifications of the PRODUCTs are required. For details, please contact the Mitsubishi
representative in your region.

5
INTRODUCTION
Thank you for purchasing the Mitsubishi MELSEC-Q series programmable controllers.
This manual describes the operating procedure, system configuration, parameter settings, functions, programming,
and troubleshooting of the Q68CT current transformer input module (hereafter abbreviated as CT input module).
Before using this product, please read this manual and the relevant manuals carefully and develop familiarity with the
functions and performance of the MELSEC-Q series programmable controller to handle the product correctly.
When applying the program examples introduced in this manual to an actual system, ensure the applicability and
confirm that it will not cause system control problems.
Relevant module: Q68CT
Remark
●Unless otherwise specified, this manual describes the program examples in which the I/O numbers of X/Y00 to X/Y0F are
assigned for a CT input module.
For I/O number assignment, refer to the following manuals.
QnUCPU User's Manual (Function Explanation, Program Fundamentals)
Qn(H)/QnPH/QnPRHCPU User's Manual (Function Explanation, Program Fundamentals)
●Operating procedures are explained using GX Works2. When using GX Developer, refer to the following.
• When using GX Developer ( Page 244, Appendix 2)
COMPLIANCE WITH EMC AND LOW VOLTAGE
DIRECTIVES
(1) Method of ensuring compliance
To ensure that Mitsubishi programmable controllers maintain EMC and Low Voltage Directives when incorporated
into other machinery or equipment, certain measures may be necessary. Please refer to one of the following
manuals.
• QCPU User's Manual (Hardware Design, Maintenance and Inspection)
• Safety Guidelines
(This manual is included with the CPU module or base unit.)
The CE mark on the side of the programmable controller indicates compliance with EMC and Low Voltage
Directives.
(2) Additional measures
No additional measures are necessary for the compliance of this product with EMC and Low Voltage Directives.

6
RELEVANT MANUALS
(1) CPU module user's manual
(2) Programming manual
(3) Operating manual
Manual name
<manual number (model code)> Description
QCPU User's Manual (Hardware Design, Maintenance and
Inspection)
<SH-080483ENG, 13JR73>
Specifications of the hardware (CPU modules, power supply modules,
base units, extension cables, and memory cards), system maintenance
and inspection, troubleshooting, and error codes
QnUCPU Users Manual (Function Explanation, Program
Fundamentals)
<SH-080807ENG, 13JZ27> Functions, methods, and devices for programming
Qn(H)/QnPH/QnPRHCPU User's Manual (Function
Explanation, Program Fundamentals)
<SH-080808ENG, 13JZ28>
Manual name
<manual number (model code)> Description
MELSEC-Q/L Programming Manual (Common Instruction)
<SH-080809ENG, 13JW10> Detailed description and usage of instructions used in programs
Manual name
<manual number (model code)> Description
GX Works2 Version1 Operating Manual (Common)
<SH-080779ENG, 13JU63>
System configuration, parameter settings, and online operations (common
to Simple project and Structured project) of GX Works2
GX Developer Version 8 Operating Manual
<SH-080373E, 13JU41>
Operating methods of GX Developer, such as programming, printing,
monitoring, and debugging

7
Memo

CONTENTS
8
CONTENTS
SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
CONDITIONS OF USE FOR THE PRODUCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
COMPLIANCE WITH EMC AND LOW VOLTAGE DIRECTIVES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
RELEVANT MANUALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
MANUAL PAGE ORGANIZATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
TERM. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
PACKING LIST . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
CHAPTER 1 OVERVIEW 15
1.1 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
CHAPTER 2 SYSTEM CONFIGURATION 18
2.1 Applicable Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .18
2.2 How to Check the Function Version and Serial Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .22
CHAPTER 3 SPECIFICATIONS 24
3.1 General Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .24
3.2 Performance Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.1 Performance specifications list. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.2 I/O conversion characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.2.3 Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3.2.4 Number of parameter settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
3.3 Function list. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .31
CHAPTER 4 FUNCTIONS 33
4.1 Processing Each Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
4.2 Input Range Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .34
4.3 Conversion Enable/Disable Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
4.4 Sampling Cycle Switching Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4.5 Digital Conversion Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.5.1 Operations of digital conversion methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4.5.2 Setting procedures for digital conversion methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
4.6 Input Signal Error Detection Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4.7 Peak Current Detection Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .44
4.8 Dropout Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
4.9 Scaling Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
4.10 Warning Output Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
4.11 Maximum Value/Minimum Value Hold Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
4.12 Logging Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4.13 Set Value Backup Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
4.14 Default Setting Registration Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
4.15 Error History Function. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
4.16 Module Error Collection Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.17 Error Clear Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

9
CHAPTER 5 I/O SIGNALS ASSIGNED TO THE CPU MODULE 77
5.1 I/O Signal List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77
5.2 Details of I/O Signals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.2.1 Input signal. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 78
5.2.2 Output signal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
CHAPTER 6 BUFFER MEMORY 89
6.1 List of Buffer Memory Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
6.2 Details of Buffer Memory Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .104
CHAPTER 7 SETTINGS AND THE PROCEDURE BEFORE OPERATION 136
7.1 Handling Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136
7.2 Settings and the Procedure Before Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
7.3 Part Names. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .138
7.4 Wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .140
7.4.1 Wiring precautions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140
7.4.2 External wiring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
CHAPTER 8 VARIOUS SETTINGS 142
8.1 Adding a Module. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .142
8.2 Switch Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .143
8.3 Parameter Setting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .144
8.4 Auto Refresh. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .147
8.5 Offset/gain Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148
8.5.1 Setting from "Offset/Gain Setting" of GX Works2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148
8.5.2 Setting from a program . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
CHAPTER 9 PROGRAMMING 155
9.1 Programming Procedure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .155
9.2 When Using the Module in a Standard System Configuration . . . . . . . . . . . . . . . . . . . . . . . .156
9.2.1 Program example when using parameters of the intelligent function module . . . . . . . . . . . 158
9.2.2 Program example when not using parameters of the intelligent function module . . . . . . . . 162
9.3 When Using the Module on the Remote I/O Network. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .165
9.3.1 Program example when using parameters of the intelligent function module . . . . . . . . . . . 173
9.3.2 Program example when not using parameters of the intelligent function module . . . . . . . . 175
CHAPTER 10 ONLINE MODULE CHANGE 180
10.1 Precautions on Online Module Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .180
10.2 Conditions for Online Module Change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181
10.3 Online Module Change Operations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182
10.4 Online Module Change Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .183

10
10.5 When a Factory Default Range Is Used and Parameters Are Set Using the Configuration
Function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 185
10.6 When a Factory Default Range Is Used and Parameters Are Set Using a Sequence Program
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190
10.7 When a User Range Is Used and Parameters Are Set Using the Configuration Function
(with Another System) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196
10.8 When a User Range Is Used and Parameters Are Set Using a Sequence Program
(with Another System) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
10.9 When a User Range Is Used and Parameters Are Set Using the Configuration Function
(without Another System) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 207
10.10 When a User Range Is Used and Parameters Are Set Using a Sequence Program
(without Another System) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 213
10.11 Range Reference Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .220
CHAPTER 11 TROUBLESHOOTING 221
11.1 Error Code List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
11.2 Alarm Code List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .228
11.3 Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
11.3.1 When the RUN LED flashes or turns off . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
11.3.2 When the ERR. LED turns on or flashes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 229
11.3.3 When the ALM LED turns on or flashes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
11.3.4 When a digital output value cannot be read. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230
11.3.5 When Conversion completed flag does not turn on in the normal mode . . . . . . . . . . . . . . . 231
11.4 Checking the CT Input Module Status on GX Works2 System Monitor . . . . . . . . . . . . . . . . .232
APPENDICES 233
Appendix 1 Dedicated Instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .233
Appendix 1.1 G(P).OFFGAN. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234
Appendix 1.2 G(P).OGLOAD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 236
Appendix 1.3 G(P).OGSTOR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240
Appendix 2 When Using GX Developer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .244
Appendix 2.1 Operation of GX Developer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 244
Appendix 3 External Dimensions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .246
INDEX 248
REVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 250
WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251

11
MANUAL PAGE ORGANIZATION
In this manual, pages are organized and the symbols are used as shown below.
The following illustration is for explanation purpose only, and should not be referred to as an actual documentation.
*1 The mouse operation example is provided below.
The section of
the current page is shown.
The chapter of
the current page is shown.
"" is used for window
names and items.
[ ] is used for items in
the menu bar and the
project window.
shows operating
procedures.
shows reference
manuals.
shows notes that
require attention.
shows mouse
operations.*1
shows reference
pages.
shows setting or
operating examples.
Ex.
shows useful
information.
A window selected in the view selection area is displayed.
View selection area
[Online] [Write to PLC...]
Select [Online] on the menu bar,
and then select [Write to PLC...].
Project window [Parameter]
[PLC Parameter]
Select [Project] from the view selection
area to open the Project window.
Menu bar
Ex.
Ex.
In the Project window, expand [Parameter] and
select [PLC Parameter].

12
Pages describing instructions are organized as shown below.
The following illustration is for explanation purpose only, and should not be referred to as an actual documentation.
Descriptions of
setting data and data type
Instruction name
Structure of the instruction
in the ladder mode
shows the devices
applicable to the instruction
Descriptions of
control data (if any)
Execution condition of the instruction
Setting side
User : Device value is set by the user.
System: Device value is set by
the CPU module.
C
onditions for the error and
error codes
For the errors not described in
this manual, refer to the following.
QCPU User's Manual
(Hardware Design, Maintenance
and Inspection)
Simple program example(s)
and descriptions of the devices used
Detailed descriptions
of the instruction

13
• Instructions can be executed under the following conditions.
• The following devices can be used.
*1 For details on each device, refer to the following.
QnUCPU User's Manual (Function Explanation, Program Fundamentals)
Qn(H)/QnPH/QnPRHCPU User's Manual (Function Explanation, Program Fundamentals)
*2 FX and FY can be used for bit data only, and FD for word data only.
*3 In the "Constant" and "Others" columns, a device(s) that can be set for each instruction is shown.
• The following data types can be used.
Execution condition Any time During on On the rising
edge During off On the falling edge
Symbol No symbol
Setting
data
Internal device
(system, user) File
register
Link direct device
J\
Intelligent
function
module device
U\G
Index
register
Zn
Constant
*3
Others
*3
Bit Word Bit Word
Applicable
device*1
X, Y, M, L,
SM, F, B,
SB, FX,
FY
*2
T, ST, C, D,
W, SD,
SW, FD,
@
R, ZR - U\GZ K, H, E, $
P, I, J, U,
D, X, DY,
N, BL,
TR, BL\S,
V
Data type Description
Bit Bit data or the start number of bit data
BIN 16-bit 16-bit binary data or the start number of word device
BIN 32-bit 32-bit binary data or the start number of double-word device
BCD 4-digit Four-digit binary-coded decimal data
BCD 8-digit Eight-digit binary-coded decimal data
Real number Floating-point data
Character string Character string data
Device name Device name data

14
TERM
Unless otherwise specified, this manual uses the following terms.
PACKING LIST
The product package contains the following.
Term Description
CT input module The abbreviation for the Q68CT current transformer input module
CT Another term for a current transformer
QCPU Another term for the MELSEC-Q series CPU module
Process CPU A generic term for the Q02PHCPU, Q06PHCPU, Q12PHCPU, and Q25PHCPU
Redundant CPU A generic term for the Q12PRHCPU and Q25PRHCPU
GX Works2 Product name of the software package for the MELSEC programmable
controllers
GX Developer
Programming tool Generic term for GX Works2 and GX Developer
CT input value An alternating current value measured using a CT. This manual describes a
primary current value as a CT input value.
Factory default range A generic term for factory-default input ranges (0 to 5AAC, 0 to 50AAC, 0 to
100AAC, 0 to 200AAC, 0 to 400AAC, and 0 to 600AAC)
User range A generic term for user-defined input ranges (0 to 5AAC, 0 to 50AAC, 0 to
100AAC, 0 to 200AAC, 0 to 400AAC, and 0 to 600AAC)
Buffer memory The memory of an intelligent function module used to store data (such as setting
values and monitored values) for communication with a CPU module.
Model Product Quantity
Q68CT Q68CT current transformer input module 1
- Before Using the Product (BCN-P5901) 1

15
CHAPTER 1 OVERVIEW
1
CHAPTER 1 OVERVIEW
(1) CT
A CT means "Current Transformer" and is a current sensor which is necessary to measure an alternating current.
A CT is used for the following purposes widely.
• To control a load or monitor an operation of equipment and devices
• To control or monitor of an electric power system
When a high current is measured in an electric power receiving facility, measurement devices cannot be wired
directly. A CT is used for such a situation.
(a) Mechanism of a CT
A CT utilizes characteristics of an alternating current.
There are two CT types: the contact type and noncontact type. The noncontact type is classified into the
window-type and split-type which is easy to be retrofitted.
(2) Operation of a CT input module
A CT input module measures an alternating current by converting a secondary current input from a CT to a digital
value after carrying out an effective value operation.
The above flows are defined as "digital conversion" in this manual.
( )
K
L
k
I
Primary current (I1)
Primary windings (T1)
Secondary current (I2)
Secondary windings (T2)
Primary current (I1) Windings (T1) = Secondary current (I2) Windings (T2)
=
Current transformation
ratio (CT ratio)
Primary current (I1)
Secondary current (I2)
Secondary windings (T2)
Primary windings (T1)
Primary and secondary coils winded an iron core are isolated
electrically. When a primary current (I1) is applied to the iron
core, a secondary current (I2) can be extracted depending on
the turn ratio (current transformation ratio).
The following shows the relationship of a primary current, a
secondary current, and windings
Primary coil Secondary coil
Iron core

16
1.1 Features
(1) Alternating current measurement of eight points (eight channels) by one
module
One module can measure an alternating current with eight points (eight channels).
A CT input range can be selected for each channel.
(2) Reliability by high accuracy
A CT input module can achieve the high accuracy of ±0.5% (when the ambient temperature is 25 ± 5°C) and
±1.0% (when the ambient temperature is 0 to 55°C) at the maximum digital output value.
(3) Operation of a digital output value by the scaling function
The scaling function can represent a digital output value in an easily understandable value depending on a
purpose.
(4) Monitoring of a measured target
By using the input signal error detection function, warning output function, or dropout function, the status of a
measured target can be monitored easily.
(5) Detection of the peak current
• By setting the peak current detection value and peak current detection time, the peak current occurred
excessively at a system start-up or an overload of devices can be detected. Doing so improves
maintainability of devices and the failure diagnosis for a measured target.
• The number of peak current detection is recorded in a non-volatile memory. Therefore the number of peak
current detection is not cleared after turning off the power supply or resetting the CPU module.
CT input module
8 points (8 channels)
Measured
target 1
Measured
target 2
Measured
target 8
CT
CT
CT
Current values from a CT
Peak current
detection value
Alarm ON
Peak current
detection time
Time

17
CHAPTER 1 OVERVIEW
1
1.1 Features
(6) Logging function
5000 data can be collected for each channel. The analysis of the collected data can improves maintainability of
the system used.
(7) Backup of a set value to a non-volatile memory
Initial settings in the buffer memory can be backed up to a non-volatile memory. Initial settings do not need to be
reset when the power supply is turned on or the CPU module is reset.
(8) Changeable slope of I/O conversion characteristics
A slope of I/O conversion characteristics can be changed by configuring the offset/gain settings.
(9) Easy setting with GX Works2
Sequence programming is reduced since initial settings or an auto refresh setting can be configured on the
screen. In addition, setting status and operating status of modules can be checked easily.
(10)Online module change
This module can be replaced without stopping the system.
(11)Reduced man-hours and costs (A signal converter is not needed.)
A CT can be connected to a programmable controller directory using a CT input module; as a result, a signal
converter installed outside is not required. Therefore man-hours and costs are reduced.
Analog input module
DC voltage or
DC electricity
Signal converter
Primary current
CT
Secondary current
Measured target Measured target
<<Existing system>>
CT input module
Primary current
Secondary current
CT
Measured target Measured target
<<System with a CT input module>>
Signal converters
are not required.

18
CHAPTER 2 SYSTEM CONFIGURATION
This chapter describes the system configuration of the CT input module.
2.1 Applicable Systems
This section describes applicable systems.
(1) Applicable CPU modules and base units, and number of mountable modules
(a) When mounted with a CPU module
For the CPU modules, the number of modules, and base units applicable to the Q68CT, refer to the user's
manual for the CPU module used.
Note the following when the Q68CT is mounted with a CPU module.
• Depending on the combination with other modules or the number of mounted modules, power supply
capacity may be insufficient. Pay attention to the power supply capacity before mounting modules, and if
the power supply capacity is insufficient, change the combination of the modules.
• Mount a module within the number of I/O points for the CPU module. If the number of slots is within the
available range, the module can be mounted on any slot.
Remark
To use a C Controller module with the CT input module, refer to the C Controller Module User's Manual.
(b) When mounted on MELSECNET/H remote I/O station
For the MELSECNET/H remote I/O station, the number of modules, and base units applicable to the Q68CT,
refer to the Q Corresponding MELSECNET/H Network System Reference Manual (Remote I/O network).