Mitsubishi MELSEC Q Series Owner's manual

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SAFETY PRECAUTIONS 
(Read these precautions before using this product.)
Before using MELSEC-Q, -L, or -QnA series programmable controllers, please read the manuals included
with each product and the relevant manuals introduced in those manuals carefully, and pay full attention
to safety to handle the product correctly.
Make sure that the end users read the manuals included with each product, and keep the manuals in a
safe place for future reference.

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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;
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.

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REVISIONS
* The manual number is given on the bottom left of the back cover.
Print Date * Manual Number Revision
Dec., 1999 SH (NA) 080041-A First edition
May, 2001 SH (NA) 080041-B Partial correction
Chapter 1, Section 3.1, Appendix 2
Apr., 2002 SH (NA) 080041-C Partial correction
Chapter 1, 2, Section 3.1, 3.3, 5.1, 5.1.1, 5.1.2, Appendix 2
Mar., 2003 SH (NA) 080041-D Descriptions on use of MELSAP-3 with the Basic model QCPU whose
serial number (first five digits) is "04122" or later have been added.
Overall reexamination
Jun., 2004 SH (NA) 080041-E Descriptions on the Redundant CPU have been added.
May, 2005 SH (NA) 080041-F Partial correction
ABOUT MANUALS, Section 4.4.2, 4.4.9, 6.6, Appendix 1.1
Addition
Section 3.3.2, 4.8, 4.8.1, 4.8.2
Section number change
Section 3.3 Section 3.3.1
Mar., 2006 SH (NA) 080041-G Partial correction
Section 3.1.1, 3.1.2, 3.1.3, Appendix 1.1, 1.2
Apr., 2007 SH (NA) 080041-G New models of the Universal model QCPU have been added.
Model addition
Q02UCPU, Q03UDCPU, Q04UDHCPU, Q06UDHCPU
Partial correction
ABOUT MANUALS, GENERIC TERMS, Chapter 1, 2, Section 3.1.2,
3.2.2, 3.3.1, 4.2, 4.4.1 to 4.4.11, 4.5 to 4.7, 5.2, 5.2.1, 5.2.2, 5.3.1, 6.6,
Appendix 1.1, 1.2, 2, 3
Dec., 2007 SH (NA) 080041-H Partial correction
Section 6.3.2
Feb., 2008 SH (NA) 080041-I New models of the Universal model QCPU have been added.
Model addition
Q13UDHCPU, Q26UDHCPU
Partial correction
GENERIC TERMS, Chapter 2, Section 3.1.2, 3.2.2, 3.3.1, 4.2, 4.2.1,
4.2,8, 4.3.3, 4.4.5, 5.2.2, Appendix 2
May, 2008 SH (NA) 080041-J New models of the Universal model QCPU and Process CPU have
been added.
Model addition
Q03UDECPU, Q04UDEHCPU, Q06UDEHCPU, Q13UDEHCPU,
Q26UDEHCPU
Q02PHCPU, Q06PHCPU
Partial correction
GENERIC TERMS, Chapter 2, Section 3.1.2, 3.3.1, 4.2, 4.2.8, 4.3.3,
4.7.1, 5.2.2, Appendix 2

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* The manual number is given on the bottom left of the back cover.
Print Date * Manual Number Revision
Dec., 2008 SH (NA) 080041-K New models of the Universal model QCPU have been added.
Model addition
Q00UJCPU, Q00UCPU, Q01UCPU, Q10UDHCPU, Q10UDEHCPU,
Q20UDHCPU, Q20UDEHCPU
Partial correction
ABOUT MANUALS, GENERIC TERMS, Section 1.1, 1.2, Chapter 2,
Section 3.1.2, 4.3.1, 4.3.3, 5.2.2, Appendix 1, 2
Jul., 2009 SH (NA) 080041-L The serial number (first five digits) of the Universal model QCPU has
been upgraded to "11043".
Partial correction
Section 4.1, 4.7.1, 6.1.1
Jan., 2010 SH (NA) 080041-M Descriptions on MELSEC-L series modules have been added.
Partial correction
ABOUT MANUALS, GENERIC TERMS, Chapter 1, Section 1.2,
Chapter 2, Section 3.1.2, 3.1.3, 3.2.1, 3.2.2, 3.2.3, 3.2.5, 3.3.1, 4.2,
4.2.2, 4.2.7, 4.2.8, 4.2.9, 4.2.10, 4.2.11, 4.3.1, 4.3.3, 4.3.5, 4.4, 4.4.1,
4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.4.6, 4.4.7, 4.4.8, 4.4.9, 4.4.10, 4.4.11, 4.5,
4.5.3, 4.6, 4.7, 4.7.1, 4.7.3, 4.7.4, 4.7.5, 4.7.6, 4.8.1, 4.8.2, 5.2, 5.2.1,
5.2.2, 5.2.3, 5.3.1, 6.1, 6.1.1, 6.3.1, 6.3.2, 6.4.3, 6.6, Appendix 1.1,
1.2, 3
Addition
CONDITIONS OF USE FOR THE PRODUCT, Section 3.2.4
Apr., 2010 SH (NA) 080041-N New models of the Universal model QCPU have been added.
Model addition
Q50UDEHCPU, Q100UDEHCPU
Partial correction
GENERIC TERMS, Chapter 2, Section 3.1.2, 3.3.1, 4.2, 4.2.8, 4.3.3,
5.2.2, Appendix 2
Aug., 2010 SH (NA) 080041-O The serial number (first five digits) of the Universal model QCPU has
been upgraded to "12052".
Partial correction
Section 3.1.2, 3.2.3, 3.3.2, 4.2, 4.2.8, 4.2.9, 4.4, 4.4.6, 4.4.8, 4.4.9,
4.5, 4.7, 4.7.5, 4.8, 4.8.1, 6.6, Appendix 1.1, 1.2
Addition
Section 6.6.1, 6.6.2, 6.6.3
Dec., 2010 SH (NA) 080041-P Partial correction
Section 4.3.4
Jul., 2011 SH (NA) 080041-Q New models of the LCPU have been added.
Model addition
L02CPU-P, L26CPU-PBT
Partial correction
GENERIC TERMS, Section 1.2, Chapter 2, Section 3.1.2,
3.2.4, 3.3.1, 4.2, 4.2.8, 4.2.9, 4.3.1, 4.3.3, 5.2.2, Appendix 2

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* The manual number is given on the bottom left of the back cover.
Print Date * Manual Number Revision
Nov., 2011 SH (NA) 080041-R The serial number (first five digits) of the Universal model QCPU has
been upgraded to "13102".
Partial correction
SAFETY PRECAUTIONS, ABOUT MANUALS, Chapter 4, Section 4.4,
4.4.1, 4.4.8, 4.4.10, 6.1, 6.6.3, Appendix 1, 2, 3
Feb., 2013 SH (NA) 080041-S New models of the Universal model QCPU and LCPU have been
added.
Model addition
Q03UDVCPU, Q04UDVCPU, Q06UDVCPU, Q13UDVCPU,
Q26UDVCPU, L02SCPU, L06CPU, L26CPU
Partial correction
GENERIC TERMS, Section 1.2, Chapter 2, Section 3.1.2, 3.2.4, 3.3.1,
4.2, 4.2.8, 4.2.9, 4.3.1, 4.3.3, 5.2.2, 6.6, Appendix 2
Jun., 2013 SH (NA) 080041-T New models of the LCPU have been added.
Model addition
L02SCPU-P, L06CPU-P, L26CPU-P
Partial correction
GENERIC TERMS, Section 1.2, Chapter 2, Section 3.1.2, 3.2.4, 3.3.1,
4.2, 4.2.8, 4.2.9, 4.3.1, 4.3.3, 5.2.2, 6.6, Appendix 2
Jan., 2014 SH(NA) 080041-U The serial number of the LCPU has been upgraded to "15102".
Partial correction
Section 3.1.2, 3.2.4, 3.3.2, 4.2, 4.2.8, 4.2.9, 4.7, 4.7.5, 4.8.1, 4.8.2,
6.6, Appendix 1, 2, 3
Japanese Manual Version SH-080023-AB
This manual confers no industrial property rights or any rights of any other kind, nor does it confer any patent
licenses. Mitsubishi Electric Corporation cannot be held responsible for any problems involving industrial property
rights which may occur as a result of using the contents noted in this manual.
1999 MITSUBISHI ELECTRIC CORPORATION

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INTRODUCTION
Thank you for purchasing the Mitsubishi MELSEC-Q/L/QnA series programmable controllers.
Before using the product, please read this manual carefully and develop familiarity with the functions and
performance of the MELSEC-Q/L/QnA series programmable controllers to handle the product correctly.
Please make sure that the end users read this manual.
CONTENTS
SAFETY PRECAUTIONS............................................................................................................................ A- 1
CONDITIONS OF USE FOR THE PRODUCT ........................................................................................... A- 2
REVISIONS.................................................................................................................................................. A- 3
INTRODUCTION.......................................................................................................................................... A- 6
CONTENTS.................................................................................................................................................. A- 6
ABOUT MANUALS ...................................................................................................................................... A- 9
GENERIC TERMS .........................................................................................................................................A-10
1. GENERAL DESCRIPTION 1- 1 to 1-11
1.1 Description of SFC Program.................................................................................................................. 1- 2
1.2 SFC (MELSAP3) Features .................................................................................................................... 1- 4
2. SYSTEM CONFIGURATION 2- 1 to 2- 4
3. SPECIFICATIONS 3- 1 to 3-30
3.1 Performance Specifications Related to SFC Programs ....................................................................... 3- 1
3.1.1 When the Basic model QCPU is used............................................................................................ 3- 1
3.1.2 When the High Performance model QCPU, Process CPU, Redundant CPU,
Universal model CPU, or LCPU is used ........................................................................................ 3- 3
3.1.3 Performance specifications of QnACPU ........................................................................................ 3- 7
3.2 Device List.............................................................................................................................................. 3- 9
3.2.1 Device list of Basic model QCPU ................................................................................................... 3- 9
3.2.2 Device list of High Performance model QCPU, Process CPU, and Redundant CPU.................... 3-11
3.2.3 Device list of Universal model QCPU............................................................................................... 3-13
3.2.4 Device list of LCPU ........................................................................................................................... 3-16
3.2.5 Device list of QnACPU...................................................................................................................... 3-17
3.3 Processing Time ...................................................................................................................................... 3-19
3.3.1 Processing time for SFC program .................................................................................................... 3-19
3.3.2 Processing time for S(P).SFCSCOMR instruction and S(P).SFCTCOMR instruction ................... 3-25
3.4 Calculating the SFC Program Capacity .................................................................................................. 3-28
4. SFC PROGRAM CONFIGURATION 4- 1 to 4-113
4.1 List of SFC Diagram Symbols ............................................................................................................... 4- 2
4.2 Steps....................................................................................................................................................... 4- 5
4.2.1 Step (without step attribute)...................................................................................................... 4- 6
4.2.2 Initial step ................................................................................................................................... 4- 8
4.2.3 Dummy step ............................................................................................................................... 4- 9

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4.2.4 Coil HOLD step SC ........................................................................................................................ 4- 9
4.2.5 Operation HOLD step (without transition check) SE ...................................................................... 4-12
4.2.6 Operation HOLD step (with transition check) ST ........................................................................... 4-14
4.2.7 Reset step R.................................................................................................................................... 4-16
4.2.8 Block START step (with END check) .......................................................................................... 4-17
4.2.9 Block START step (without END check) .................................................................................... 4-19
4.2.10 End step........................................................................................................................................... 4-21
4.2.11 Instructions that cannot be used with operation outputs ............................................................... 4-23
4.3 Transition.................................................................................................................................................. 4-24
4.3.1 Serial transition.................................................................................................................................. 4-25
4.3.2 Selection transition ............................................................................................................................ 4-27
4.3.3 Parallel transition............................................................................................................................... 4-30
4.3.4 Jump transition .................................................................................................................................. 4-34
4.3.5 Precautions when creating sequence programs for operation outputs (steps) and transition
conditions .......................................................................................................................................... 4-35
4.4 Controlling SFC Programs by Instructions (SFC Control Instructions) .................................................. 4-38
4.4.1 Step operation status check instructions (LD, LDI, AND, ANI, OR, ORI) ....................................... 4-43
4.4.2 Forced transition check instruction (LD, LDI, AND, ANI, OR, ORI)................................................. 4-46
4.4.3 Block operation status check instruction (LD, LDI, AND, ANI, OR, ORI)........................................ 4-48
4.4.4 Active step batch readout instructions (MOV, DMOV) .................................................................... 4-50
4.4.5 Active step batch readout (BMOV)................................................................................................... 4-53
4.4.6 Block START & END instructions (SET, RST)................................................................................. 4-57
4.4.7 Block STOP and RESTART instructions (PAUSE, RSTART)......................................................... 4-59
4.4.8 Step START and END instructions (SET, RST) .............................................................................. 4-62
4.4.9 Forced transition EXECUTE & CANCEL instructions (SET, RST) ................................................. 4-67
4.4.10 Active step change instruction (SCHG).......................................................................................... 4-69
4.4.11 Block switching instruction (BRSET) .............................................................................................. 4-70
4.5 SFC Information Devices......................................................................................................................... 4-72
4.5.1 Block START/END bit ....................................................................................................................... 4-73
4.5.2 Step transition bit............................................................................................................................... 4-75
4.5.3 Block STOP/RESTART bit................................................................................................................ 4-77
4.5.4 Block STOP mode bit........................................................................................................................ 4-79
4.5.5 Continuous transition bit.................................................................................................................... 4-81
4.5.6 "Number of active steps" register ..................................................................................................... 4-83
4.6 Step Transition Watchdog Timer............................................................................................................. 4-84
4.7 SFC Operation Mode Setting .................................................................................................................. 4-86
4.7.1 SFC program start mode .................................................................................................................. 4-87
4.7.2 Block 0 START condition .................................................................................................................. 4-89
4.7.3 Output mode at block STOP............................................................................................................. 4-90
4.7.4 Periodic execution block setting ....................................................................................................... 4-92
4.7.5 Operation mode at double block START ......................................................................................... 4-93
4.7.6 Operation mode at transition to active step (double step START).................................................. 4-94
4.8 SFC Comment Readout Instruction ........................................................................................................ 4-97
4.8.1 SFC comment readout instruction (S(P). SFCSCOMR).................................................................. 4-98
4.8.2 SFC transition comment readout instruction (S(P). SFCTCOMR) ................................................ 4-106

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5. SFC PROGRAM PROCESSING SEQUENCE 5- 1 to 5-14
5.1 Whole Program Processing of Basic Model QCPU.............................................................................. 5- 1
5.1.1 Whole program processing sequence............................................................................................ 5- 1
5.2 Whole Program Processing of High Performance Model QCPU, Process CPU, Redundant CPU,
Universal model QCPU, LCPU, and QnACPU..................................................................................... 5- 2
5.2.1 Whole program processing sequence............................................................................................ 5- 2
5.2.2 Execution type designation by instructions .................................................................................... 5- 4
5.2.3 SFC program for program execution management ....................................................................... 5- 6
5.3 SFC Program Processing Sequence .................................................................................................... 5- 8
5.3.1 SFC program execution .................................................................................................................. 5- 8
5.3.2 Block execution sequence ................................................................................................................ 5-10
5.3.3 Step execution sequence.................................................................................................................. 5-11
5.3.4 Continuous transition ON/OFF operation......................................................................................... 5-12
6. SFC PROGRAM EXECUTION 6- 1 to 6-24
6.1 SFC Program START and STOP.......................................................................................................... 6- 1
6.1.1 SFC program resumptive START procedure................................................................................. 6- 2
6.2 Block START and END.......................................................................................................................... 6- 4
6.2.1 Block START methods.................................................................................................................... 6- 4
6.2.2 Block END methods ........................................................................................................................ 6- 5
6.3 Block Temporary Stop and Restart Methods........................................................................................ 6- 6
6.3.1 Block STOP methods...................................................................................................................... 6- 6
6.3.2 Restarting a stopped block ............................................................................................................. 6- 9
6.4 Step START (Activate) and END (Deactivate) Methods ........................................................................ 6-11
6.4.1 Step START (activate) methods....................................................................................................... 6-11
6.4.2 Step END (deactivate) methods ....................................................................................................... 6-12
6.4.3 Changing an active step status (Not available for Basic model QCPU,
Universal model QCPU, and LCPU) ................................................................................................ 6-13
6.5 Operation Methods for Continuous Transition ........................................................................................ 6-14
6.6 Operation at Program Change ................................................................................................................ 6-15
6.6.1 Operation at program change made by write to PLC ...................................................................... 6-16
6.6.2 Program change by online change................................................................................................... 6-17
6.6.3 Online change (inactive block).......................................................................................................... 6-18
APPENDICES APP- 1 to APP-24
APPENDIX 1 Special Relay and Special Register List ....................................................................... APP- 1
APPENDIX 1.1 Special Relay (SM) List............................................................................................. APP- 2
APPENDIX 1.2 Special Register (SD) List ......................................................................................... APP- 6
APPENDIX 2 MELSAP-II and MELSAP3 Comparison....................................................................... APP- 7
APPENDIX 3 Restrictions on Basic Model QCPU, Universal Model QCPU,
and LCPU and Alternative Methods...................................................................................................APP-18
APPENDIX 3.1 Step Transition Watchdog Timer Replacement Method............................................APP-20
APPENDIX 3.2 Periodic Execution Block Replacement Method ........................................................APP-21
APPENDIX 3.3 Forced Transition Bit (TRn) Replacement Method ....................................................APP-22
APPENDIX 3.4 Active Step Change Instruction (SCHG) Replacement Method ................................APP-23

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ABOUT MANUALS
The manuals related to this product are listed below.
Order each manual as needed, referring to the following lists.
Relevant manuals
Manual name Manual number
(model code)
GX Developer Version 8 Operating Manual (SFC)
Describes how to create SFC programs using the software package for creating SFC
programs. (Sold separately)
SH-080374E
(13JU42)
GX Works2 Version1 Operating Manual (Common)
Describes system configurations, parameter settings, online operations (common to Simple
project and Structured project) of GX Works2. (Sold separately)
SH-080779ENG
(13JU63)
TYPE SW2IVD/NX-GPPQ GPP Software package Operating Manual (SFC)
Describes how to create SFC programs using the software package for creating SFC
programs. (Supplied with the product)
only for QnACPU
IB-66776
(13J923)
QnUCPU User's Manual (Function Explanation, Programming Fundamentals)
Describes the functions, programming procedures, devices, etc. necessary to create
programs using the QCPU. (Sold separately)
SH-080807ENG
(13JZ27)
Qn(H)/QnPH/QnPRHCPU User's Manual (Function Explanation, Programming
Fundamentals)
Describes the functions, programming procedures, devices, etc. necessary to create
programs using the QCPU. (Sold separately)
SH-080808ENG
(13JZ28)
MELSEC-L CPU Module User's Manual (Function Explanation, Program Fundamentals)
Describes the functions required for programming, programming methods, and devices.
(Sold separately)
SH-080889ENG
(13JZ35)
MELSEC-Q/L Programming Manual (Common instruction)
Describes how to use sequence instructions, basic instructions, and application instructions.
(Sold separately)
SH-080809ENG
(13JW10)
QnACPU Programming Manual (Common instruction)
Describes how to use sequence instructions, basic instructions, and application instructions.
(Sold separately)
SH-080810ENG
(13JW11)
QnACPU Programming Manual (Fundamentals)
Describes the programming procedures, device names, parameters, program types, etc.
necessary to create programs. (Sold separately)
IB-66614
(13JF46)

A-10 A-10
GENERIC TERMS
Unless otherwise specified, this manual uses the following generic terms and
abbreviations.
Generic term Description
QCPU A generic term for the Basic model QCPU, High Performance model QCPU,
Process CPU, Redundant CPU, and Universal model QCPU
QnCPU A generic term for the Q02CPU
QnHCPU A generic term for the Q02HCPU, Q06HCPU, Q12HCPU, and Q25HCPU
QnPHCPU A generic term for the Q02PHCPU, Q06PHCPU, Q12PHCPU, and Q25PHCPU
QnPRHCPU A generic term for the Q12PRHCPU and Q25PRHCPU
QnUDVCPU A generic term for the Q03UDVCPU, Q04UDVCPU, Q06UDVCPU, Q13UDVCPU,
and Q26UDVCPU
QnUD(E)(H)CPU
A generic term for the Q03UDCPU, Q03UDECPU, Q04UDHCPU, Q04UDEHCPU,
Q06UDHCPU, Q06UDEHCPU, Q10UDHCPU, Q10UDEHCPU, Q13UDHCPU,
Q13UDEHCPU, Q20UDHCPU, Q20UDEHCPU, Q26UDHCPU, Q26UDEHCPU,
Q50UDEHCPU, and Q100UDEHCPU
LCPU A generic term for the L02SCPU, L02SCPU-P, L02CPU, L02CPU-P, L06CPU,
L06CPU-P, L26CPU, L26CPU-P, L26CPU-BT, and L26CPU-PBT
QnACPU A generic term for the Q2ASCPU, Q2ASCPU-S1, Q2ASHCPU, Q2ASHCPU-S1,
Q2ACPU, Q2ACPU-S1, Q3ACPU, Q4ACPU, and Q4ARCPU
Basic model QCPU A generic term for the Q00JCPU, Q00CPU, and Q01CPU
Basic
High Performance model QCPU A generic term for the Q02CPU, Q02HCPU, Q06HCPU, Q12HCPU, and Q25HCPU
High Performance
Process CPU A generic term for the Q02PHCPU, Q06PHCPU, Q12PHCPU, and Q25PHCPU
Redundant CPU A generic term for the Q12PRHCPU and Q25PRHCPU
Universal model QCPU A generic term for the Q00UJCPU, Q00UCPU, Q01UCPU, Q02UCPU, Q03UDCPU,
Q03UDVCPU, Q03UDECPU, Q04UDHCPU, Q04UDVCPU, Q04UDEHCPU,
Q06UDHCPU, Q06UDVCPU, Q06UDEHCPU, Q10UDHCPU, Q10UDEHCPU,
Q13UDHCPU, Q13UDVCPU, Q13UDEHCPU, Q20UDHCPU, Q20UDEHCPU,
Q26UDHCPU, Q26UDVCPU, Q26UDEHCPU, Q50UDEHCPU, and
Q100UDEHCPU
Universal
High-speed Universal model
QCPU
A generic term for the Q03UDVCPU, Q04UDVCPU, Q06UDVCPU, Q13UDVCPU,
and Q26UDVCPU

A-11 A-11
MEMO

1-1 1-1
1 GENERAL DESCRIPTION
1. GENERAL DESCRIPTION
SFC, an abbreviation for "Sequential Function Chart", is a control specification description format
in which a sequence of control operations is split into a series of steps to enable a clear
expression of the program execution sequence and execution conditions.
This manual describes the specifications, functions, instructions, programming procedures, etc.
used to perform programming with an SFC program using MELSAP3.
MELSAP3 can be used with the following CPU modules.
• Basic model QCPU whose serial number (first five digits) is 04122 or later
• High Performance model QCPU
• Process CPU
• Redundant CPU
• Universal model QCPU
• LCPU
• QnACPU
MELSAP3 conforms to the IEC Standard for SFC.
In this manual, MELSAP3 is referred to as SFC (program, diagram).
POINT
(1) The following functions cannot be executed if a parameter that sets the "high
speed interrupt cyclic interval" is loaded into a High Performance model QCPU
of which the first 5 digits of the serial number are "04012" or later.
• Step transition watch dog timer (see Section 4.6)
• Periodic execution block setting (see Section 4.7.4)
(2) The Qn(H)CPU-A (A mode) cannot use MELSAP3 explained in this manual.
The SFC function that can be used by the Qn(H)CPU-A (A mode) is "MELSAP-II".
For MELSAP-II, refer to the "MELSAP-II (SFC) Programming Manual".
1

1-2 1-2
1 GENERAL DESCRIPTION
1.1 Description of SFC Program
The SFC program consists of steps that represent units of operations in a series of machine
operations.
In each step, the actual detailed control is programmed by using a ladder circuit.
1

1-3 1-3
1 GENERAL DESCRIPTION
The SFC program performs a series of operations, beginning from the initial step, proceeding to
execute each subsequent step as the transition conditions are satisfied, and ending with the END
step.
(1) When the SFC program is started, the “initial” step is executed first.
(2) Execution of the initial step continues until transition condition 1 is satisfied. When this
transition condition is satisfied, execution of the initial step is stopped, and processing
proceeds to the step which follows the initial step.
Processing of the SFC program continues from step to step in this manner until the END step has
been executed.

1-4 1-4
1 GENERAL DESCRIPTION
1.2 SFC (MELSAP3) Features
(1) Easy to design and maintain systems
It is possible to correspond the controls of the entire facility, mechanical devices of each
station, and all machines to the blocks and steps of the SFC program on a one-to-one basis.
Because of this capability, systems can be designed and maintained with ease even by those
with relatively little knowledge of sequence programs. Moreover, programs designed by other
programmers using this format are much easier to decode than sequence programs.
Step transition
control unit for
overall process
Station 1
control unit
Station 2
control unit
Station 3
control unit
Transfer machine
Overall system
(SFC program)
Step transition control
unit for overall process
(block 0)
Station 3
control unit
(block 3)
Station 1
control unit
(block 1)
Station 2
control unit
(block 2)
Transfer machine START
(initial step)
END
(END step)
Station 3 START
(block 3 START)
Station 2 START
(block 2 START)
Station 1 START
(block 1 START)
START
(initial step)
Pallet clamp
(step 1)
Drilling
(step 2)
Pallet unclamp
(step 3)
(END step)
START
(initial step)
START
(initial step)
Pallet clamp
(step 1)
Tapping
(step 2)
Pallet unclamp
(step 3)
(END step)
Pallet clamp
(step 1)
Workpiece unloading
(step 2)
Pallet unclamp
(step 3)
(END step)
Repeated
(2) Requires no complex interlock circuitry
Interlock circuits are used only in the operation output program for each step. Because no
interlocks are required between steps in the SFC program, it is not necessary to consider
interlocks with regard to the entire system.
SOL1 SOL2
Clamp
LS-U
Clamp UP endpoint
Clamp DOWN endpoint
MTO-F
MTO-B
MT1-F
MT1-B
Headstock
rotation
MT2-R
LS10
LS-D
Carriage
(Headstock RETRACT
endpoint)
LS0
(Machining
START)
LS1
(Machining
END)
LS2
(Carriage ADVANCE
endpoint)
LS-F
(Carriage RETRACT endpoint)
LS-R

1-5 1-5
1 GENERAL DESCRIPTION
Y20
Carriage ADVANCE endpoint
Carriage ADVANCE
X3
Tran
Y21
Clamp DOWN
Step 6
Clamp DOWN endpoint
X4
Tran
Y22
Headstock ADVANCE
Step 7
Step 5
SFC program
As shown in the SFC program at left, the steps require
no “operation completed” interlock contact with the
previous step. With a conventional sequence program,
carriage FORWARD (Y20) and clamp DOWN (Y21)
interlock contacts would be required at the ladder
used for the headstock ADVANCE.
Y20
Interlock contacts
Y22
Headstock ADVANCE
Y21 X3 X4
(3) Block and step configurations can easily be changed for new control applications
• A total of 320 blocks 1 can be created in an SFC program.
• Up to 512 steps 1 can be created per block.
• Up to 2k sequence steps can be created for all blocks for operation outputs.
• Each transition condition can be created in only one ladder block.
Reduced tact times, as well as easier debugging and trial run operations are possible by
dividing blocks and steps as follows:
• Divide blocks properly according to the operation units of machines.
• Divide steps in each block properly.
320 blocks 1
Initial
step
Step 1
Block 0 Block 1 Block 319
Transition condition in only one
ladder block
512 steps
Operation output program
X0 Y20
T0
T0 Y21
X1
K20
Step 2
1
Operation output: 2k sequence steps for all blocks
Initial
step
Step 1
Step 2
Initial
step
Step 1
Step 2
REMARKS
1: For the following CPU modules, 128 blocks and 128 steps can be created.
• Basic model QCPU
• Universal model QCPU (Q00UJCPU, Q00UCPU, Q01UCPU, Q02UCPU)
• LCPU (L02SCPU, L02SCPU-P, L02CPU, L02CPU-P)

1-6 1-6
1 GENERAL DESCRIPTION
(4) Creation of multiple initial steps is possible
Multiple processes can easily be executed and combined. Initial steps are linked using a
“selection coupling” format.
When multiple initial steps (S0 to S3) are active, the step where the transition condition (t4 to
t7) immediately prior to the selected coupling is satisfied becomes inactive, and a transition to
the next step occurs. Moreover, when the transition condition immediately prior to an active
step is satisfied, the next step is executed in accordance with the parameter settings.
: Basic model QCPU, Universal model QCPU, and LCPU cannot be selected in the
parameter setting.
It operates in the default "Transfer" mode.
• Wait ............. Transition to the next step occurs after waiting for the next step to become
inactive.
• Transfer....... Transition to the next step occurs even if the next step is active. (Default)
• Pause.......... An error occurs if the next step is active.
S8
S4
t4
S0
t0
S7
t7
S3
t3
S6
t6
S2
t2
S5
t5
S1
t1
REMARKS
Linked steps can also be changed at each initial step.
S6
S3
t3
S0
t0
S5
t5
S2
t2
S4
t4
S1
t1
S7
t6

1-7 1-7
1 GENERAL DESCRIPTION
(5) Program design is easy due to a wealth of step attributes
A variety of step attributes can be assigned to each step. Used singly for a given control
operation, or in combination, these attributes greatly simplify program design procedures.
• Types of HOLD steps, and their operations
1) Coil HOLD step ( SC )
X0
Y10
X0
Y10
Step which is active due to
transition condition being
satisfied
(Transition condition satisfied)
• After a transition, operation output
processing continues (is maintained),
and the coil output status at the time
when the transition condition is
satisfied is maintained regardless of
the ON/OFF status of the interlock
condition (X0).
• Transition will not occur even if the
transition condition is satisfied again.
• Convenient for maintaining an output
until the block in question is completed
(hydraulic motor output, pass
confirmation signal, etc.).
2) Operation HOLD step (no transition check) ( SE )
X0 Y10
X0
Y10
Step which is active due to
transition condition being
satisfied
• Even after a transition, operation
output processing continues (is
maintained), and when the interlock
condition (X0) turns ON/OFF, the coil
output (Y10) also turns ON/OFF.
• Transition will not occur if the transition
condition is satisfied again.
• Convenient for repeating the same
operation (cylinder advance/retract,
etc.) while the relevant block is active.
3) Operation HOLD step (with transition check) ( ST )
MO
X0
Y10
X1
Tran
PLS M0
(Transition executed)
Step which is active due
the previous transition
condition being satisfied
• Even after a transition, operation output
processing continues (is maintained),
and when the interlock condition (X0)
turns ON/OFF, the coil output (Y10) also
turns ON/OFF.
• When the transition condition is again
satisfied, the transition is executed, and
the next step is activated.
• Operation output processing is executed
at the reactivated next step. When the
transition condition is satisfied, transition
occurs, and the step is deactivated.
• Convenient for outputs where there is an
interlock with the next operation, for
example where machining is started on
completion of a repeated operation
(workpiece transport, etc.).