Mitsubishi MELSEC-L Series User manual

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•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 instructions given in this manual are concerned with this product. For the safety instructions of the
programmable controller system, please read the user's manual of the CPU module to use.
In this manual, the safety precautions are classified into two levels: " !WARNING" and " !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.
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
•For the operation status of each station at communication error in each station, refer to the
respective manual for each station.
The communication error may result in an accident due to incorrect output or malfunction.
•When changing data of a running programmable controller from a peripheral connected to the
CPU module or from an external device such as a personal computer connected to an intelligent
function module, configure an interlock circuit in the program to ensure that the entire system
will always operate safely.
For other controls to a running programmable controller (such as program modification or
operating status change), read relevant manuals carefully and ensure the safety before the
operation.
Especially, in the case of a control from an external device to a remote programmable controller,
immediate action cannot be taken for a problem on the programmable controller due to a
communication failure. To prevent this, configure an interlock circuit in the program, and
determine corrective actions to be taken between the external device and CPU module in case
of a communication failure.
!WARNING
!CAUTION

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[Design Precautions]
!WARNING
•Do not write data into the "system area" of the buffer memory of intelligent function modules.
Also, do not use any "use prohibited" signals as an output signal to an intelligent function
module from the CPU module.
Writing data into the "system area" or outputting a signal for " use prohibited" may cause a
programmable controller system malfunction.
[Design Precautions]
!CAUTION
•Do not install the control lines or communication cables together with the main circuit lines or
power cables.
Keep a distance of 100mm between them.
Failure to do so may result in malfunction due to noise.
[Installation Precautions]
!WARNING
•Shut off the external power supply for the system in all phases before mounting or removing the
module. Failure to do so may result in electric shock or cause the module to fail or malfunction.
[Installation Precautions]
!CAUTION
•Use the programmable controller in an environment that meets the general specifications
described in "Safety Guidelines", the manual supplied with the CPU module or head module.
Failure to do so may result in electric shock, fire, malfunction, or damage to or deterioration of
the product.
•To interconnect modules, engage the respective connectors and securely lock the module joint
lever. Incorrect interconnection may cause malfunction, failure, and drop.
•Do not directly touch any conductive parts and electronic components of the module. Doing so
can cause malfunction or failure of the module.

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[Wiring Precautions]
!WARNING
•Shut off the external power supply for the system in all phases before wiring.
Failure to do so may result in electric shock or cause the module to fail or malfunction.
•After installation and wiring, attach the included terminal cover to the product before turning it on
for operation. Failure to do so may result in electric shock.
[Wiring Precautions]
!CAUTION
•Use applicable solderless terminals and tighten them within the specified torque range. If any
spade solderless terminal is used, it may be disconnected when a screw on the terminal block
comes loose, resulting in failure.
•Connectors for external device connection must be crimped or pressed with the tool specified by
the manufacturer, or must be correctly soldered.
Incomplete connections could result in short circuit, fire, or malfunction.
•Securely connect the connector to the module.
•Place the cables in a duct or clamp them.
If not, dangling cable may swing or inadvertently be pulled, resulting in damage to the module or
cables or malfunction due to poor contact.
•Check the interface type and correctly connect the cable.
Incorrect wiring (connecting the cable to an incorrect interface) may cause failure of the module
and external device.
•Tighten the terminal block screw 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, fire, or malfunction.
•When disconnecting the cable from the module, do not pull the cable by the cable part.
For the cable with connector, hold the connector by hand and pull it out. For the cable
connected to the terminal block, loosen the terminal block screws.
Failure to do so may result in malfunction and damage to the module or cable.
•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.

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[Startup/Maintenance 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 for the system in all phases before cleaning the module or
retightening the terminal block screw. Failure to do so may result in electric shock.
[Startup/Maintenance Precautions]
!CAUTION
•Do not disassemble or modify the modules. Doing so may cause failure, malfunction, injury, or a
fire.
•Shut off the external power supply for the system in all phases before connecting or
disconnecting the module. Failure to do so may cause the module to fail or malfunction.
•Tighten the terminal block screw within the specified torque range.
Undertightening can cause drop of the component or wire, short circuit, or malfunction.
Overtightening can damage the screw and/or module, resulting in drop, short circuit, or
malfunction.
•After the first use of the module (including a display unit), the number of module
connections/disconnections is limited to 50 times. Exceeding the limit (IEC 61131-2 compliant)
may cause malfunction.
•Before handling the module, touch a conducting object such as a grounded metal to discharge
the static electricity from the human body.
Failure to do so may cause the module to fail or malfunction.

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[Operation Precautions]
!CAUTION
•When controlling a running programmable controller (especially, changing data, program
modification, and operation status change) from an external device such as a personal
computer connected to an intelligent function module, read the relevant user's manual carefully
and ensure the safety before the operation. Incorrect data change, program modification, and
status control may cause malfunction of the system, mechanical damage, or accidents.
•While set values in the buffer memory are being registered to the flash ROM in the module, do
not turn off the power to the module and do not reset the CPU module. Doing so will affect the
flash ROM data, and setting to the buffer memory and registration to the flash ROM need to be
performed again. Also, it may cause failure or malfunction of the module.
[Disposal Precautions]
!CAUTION
•When disposing of this product, treat it as industrial waste.

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•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;
yNuclear 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.
yRailway 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.
yAircraft 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.

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INTRODUCTION
Thank you for purchasing the Mitsubishi MELSEC-L series programmable controller.
This manual describes the functions of the LJ71C24 and LJ71C24-R2 serial communication modules
(hereinafter referred to as the C24) and programming.
Before using the equipment, please read this manual and the related manuals carefully to develop full
familiarity with the functions and performance of the MELSEC-L series programmable controller you have
purchased, so as to ensure correct use.
When applying the following program examples to the actual system, make sure to examine the applicability
and confirm that it will not cause system control problems.
Please make sure that the end user read this manual.
REMARKS
• Unless otherwise specified, in the program examples introduced in this manual,
I/O numbers X/Y00 to X/Y1F are assigned to the C24.
When using the program samples, I/O number must be assigned.
For I/O number assignment, refer to the following manual.
MELSEC-L CPU Module User's Manual (Function Explanation, Program
Fundamentals)
• Operating procedures are explained using GX Works2.
When using GX Developer or GX Configurator-SC, refer to Appendix 4.

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COMPLIANCE WITH THE 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
the manual 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.