Mitsubishi MELSEC Q Series Owner's manual

MELSEC-Q
Programming/Structured Programming Manual
(Process Control Instructions)

1
SAFETY PRECAUTIONS
(Always read these cautions before using the product)
Before using MELSEC-Q 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.

2
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.

3
INTRODUCTION
Thank you for purchasing the Mitsubishi MELSEC-Q series programmable controllers.
Before using this product, please read this manual and the relevant manuals carefully and develop familiarity with the
functions and performance of the 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.
Remark
In this manual, instructions are written in three programming languages:
ladder diagram for Simple projects, structured ladder/FBD and structured text language for Structured projects.
Please use GX Works2 with the version 1.98C or later for Structured projects.

CONTENTS
4
CONTENTS
SAFETY PRECAUTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
CONDITIONS OF USE FOR THE PRODUCT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
CONTENTS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
RELEVANT MANUALS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
TERMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
CHAPTER 1 OVERVIEW 10
1.1 Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
1.2 PID Control Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.3 Forward Operation and Reverse Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
1.4 PID Control Details . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
1.4.1 Proportional operation (P operation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .14
1.4.2 Integral operation (I operation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15
1.4.3 Derivative operation (D operation) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .16
1.4.4 PID operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .17
CHAPTER 2 STRUCTURE AND COMBINATIONS OF PROCESS CONTROL
INSTRUCTIONS 18
2.1 Structure of Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.2 How to Specify Data in Devices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.2.1 In the case of bit data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
2.2.2 In the case of word (16-bit) data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19
2.2.3 In the case of double word (32-bit) data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2.2.4 In the case of real number data (floating-point) data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20
2.2.5 Operation errors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
2.2.6 Execution conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
2.2.7 Number of steps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
2.2.8 Index modification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .21
2.3 Basic Loop Types Available by Combinations of Process Control Instructions . . . . . . . . . . . . . 22
CHAPTER 3 DATA USED FOR PROCESS CONTROL INSTRUCTIONS AND
HOW TO SPECIFY DATA 24
3.1 Process Control Instructions and Data Structure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
3.2 Local Work Memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
3.3 Data Used for Process Control Instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.3.1 Loop memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .27
3.3.2 Input data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .28
3.3.3 Block memory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
3.3.4 Operation constant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29
3.3.5 Loop tag memory allocation contents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .30
CHAPTER 4 HOW TO EXECUTE PROCESS CONTROL INSTRUCTIONS 33
4.1 Execution Cycle and Control Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
4.2 Concept of Program. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

5
CHAPTER 5 EXECUTION CONDITION SWITCHING AND FUNCTIONS 35
5.1 Execution Condition Switching. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
5.1.1 Loop RUN/STOP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
5.2 Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5.2.1 Tracking function . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
5.2.2 Cascade loop tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .36
5.2.3 Loop selector tracking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37
CHAPTER 6 INSTRUCTIONS 38
6.1 How to Read the Instruction List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
6.2 List of Instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
6.2.1 I/O control instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .40
6.2.2 Control operation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
6.2.3 Compensation operation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .46
6.2.4 Arithmetic operation instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .47
6.2.5 Comparison operation instructions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
6.2.6 Auto tuning instructions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .49
CHAPTER 7 HOW TO READ INSTRUCTION DETAILS 50
CHAPTER 8 I/O CONTROL INSTRUCTIONS 54
8.1 S.IN Analog Input Processing . . . . . . . . . . . . . . . . . . . . .54
8.2 S.OUT1 Output Processing-1 with Mode Switching . . . . . . .59
8.3 S.OUT2 Output Processing-2 with Mode Switching . . . . . . .65
8.4 S.MOUT Manual Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70
8.5 S.DUTY Time Proportioning . . . . . . . . . . . . . . . . . . . . . . . . . .74
8.6 S.BC Batch Counter . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81
8.7 S.PSUM Pulse Integration . . . . . . . . . . . . . . . . . . . . . . . . . . .85
CHAPTER 9 CONTROL OPERATION INSTRUCTIONS 90
9.1 S.PID Basic PID . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90
9.2 S.2PID 2-degree-of-freedom PID Control . . . . . . . . . . . . . .98
9.3 S.PIDP Position Type PID Control . . . . . . . . . . . . . . . . . . .106
9.4 S.SPI Sample PI Control . . . . . . . . . . . . . . . . . . . . . . . . .115
9.5 S.IPD I-PD Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .122
9.6 S.BPI Blend PI control . . . . . . . . . . . . . . . . . . . . . . . . . . .130
9.7 S.R Ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .137
9.8 S.PHPL High/Low Limit Alarm . . . . . . . . . . . . . . . . . . . . . . .142
9.9 S.LLAG Lead-Lag . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .148
9.10 S.I Integral . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .150
9.11 S.D Derivative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .152
9.12 S.DED Dead Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .154
9.13 S.HS High Selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . .157

6
9.14 S.LS Low Selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . .159
9.15 S.MID Middle Value Selection . . . . . . . . . . . . . . . . . . . . .161
9.16 S.AVE Average Value . . . . . . . . . . . . . . . . . . . . . . . . . . . .164
9.17 S.LIMT High/Low Limiter . . . . . . . . . . . . . . . . . . . . . . . . . .166
9.18 S.VLMT1 Variation Rate Limiter 1 . . . . . . . . . . . . . . . . . . . . .168
9.19 S.VLMT2 Variation Rate Limiter 2 . . . . . . . . . . . . . . . . . . . . .171
9.20 S.ONF2 2-position ON/OFF . . . . . . . . . . . . . . . . . . . . . . . . .174
9.21 S.ONF3 3-position ON/OFF . . . . . . . . . . . . . . . . . . . . . . . . .180
9.22 S.DBND Dead Band . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .186
9.23 S.PGS Program Setter . . . . . . . . . . . . . . . . . . . . . . . . . . . .188
9.24 S. SEL Loop Selector . . . . . . . . . . . . . . . . . . . . . . . . . . . . .193
9.25 S.BUMP Bumpless Transfer . . . . . . . . . . . . . . . . . . . . . . . . .199
9.26 S.AMR Analog Memory . . . . . . . . . . . . . . . . . . . . . . . . . . .202
CHAPTER 10 COMPENSATION OPERATION INSTRUCTIONS 205
10.1 S.FG Function Generator . . . . . . . . . . . . . . . . . . . . . . . .205
10.2 S.IFG Inverse Function Generator . . . . . . . . . . . . . . . . . .207
10.3 S.FLT Standard Filter . . . . . . . . . . . . . . . . . . . . . . . . . . . .209
10.4 S.SUM Summation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .212
10.5 S.TPC Temperature/Pressure Correction . . . . . . . . . . . . .214
10.6 S.ENG Engineering Value Conversion . . . . . . . . . . . . . . .217
10.7 S.IENG Inverse Engineering Value Conversion . . . . . . . . .219
CHAPTER 11 ARITHMETIC OPERATION INSTRUCTIONS 221
11.1 S.ADD Addition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .221
11.2 S.SUB Subtraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223
11.3 S.MUL Multiplication . . . . . . . . . . . . . . . . . . . . . . . . . . . . .225
11.4 S.DIV Division . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .227
11.5 S.SQR Square Root . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229
11.6 S.ABS Absolute Value . . . . . . . . . . . . . . . . . . . . . . . . . . . .231
CHAPTER 12 COMPARISON OPERATION INSTRUCTIONS 233
12.1 S. > Compare Greater Than . . . . . . . . . . . . . . . . . . . . .233
12.2 S. < Compare Less Than . . . . . . . . . . . . . . . . . . . . . . .235
12.3 S. = Compare Equal Than . . . . . . . . . . . . . . . . . . . . . . .237
12.4 S. >= Compare Greater Or Equal . . . . . . . . . . . . . . . . . .239
12.5 S. <= Compare Less Or Equal . . . . . . . . . . . . . . . . . . . .241
CHAPTER 13 AUTO TUNING 243
13.1 S. AT1 Auto tuning instruction . . . . . . . . . . . . . . . . . . . . . .246

7
CHAPTER 14 ERROR CODES 253
14.1 List of Error Codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253
APPENDICES 255
Appendix 1Program Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255
Appendix 2Loop Tag Memory List . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 259
Appendix 2.1PID control (SPID), 2-degree-of-freedom PID control (S2PID), sample PI control (SSPI)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .259
Appendix 2.2I-PD control (SIPD), blend PI control (SBPI) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .261
Appendix 2.3Manual output (SMOUT), monitor (SMON) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .263
Appendix 2.4Manual output with monitor (SMWM), PIDP control (SPIDP). . . . . . . . . . . . . . . . . . . . .264
Appendix 2.52 position ON/OFF control (SONF2), 3 position ON/OFF control (SONF3) . . . . . . . . . .266
Appendix 2.6Batch counter (SBC). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .267
Appendix 2.7Ratio control (SR) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .268
Appendix 3Operation Processing Time . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 270
Appendix 3.1Operation processing time of each instruction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .270
Appendix 3.2Operation processing time of 2-degree-of-freedom PID control loop . . . . . . . . . . . . . . .273
INDEX 275
INSTRUCTION INDEX 277
REVISIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 278
WARRANTY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 279

8
RELEVANT MANUALS
Manual name Manual number
(model code)
QCPU User's Manual (Hardware Design, Maintenance and Inspection)
Specifications of the CPU modules, power supply modules, base units, extension cables, memory cards, SD memory
cards, extended SRAM cassettes, and batteries, information on how to establish a system, maintenance and
inspection, and troubleshooting
(Sold separately)
SH-080483ENG
(13JR73)
Qn(H)/QnPH/QnPRHCPU User's Manual (Function Explanation, Program Fundamentals)
Functions, methods, and devices for programming
(Sold separately)
SH-080808ENG
(13JZ28)
MELSEC-Q/L Programming Manual (Common Instruction)
How to use sequence instructions, basic instructions, and application instructions
(Sold separately)
SH-080809ENG
(13JW10)
MELSEC-Q/L/QnA Programming Manual (SFC)
System configuration, performance specifications, functions, programming, debugging, and error codes for SFC
(MELSAP3) programs
(Sold separately)
SH-080041
(13JF60)
MELSEC-Q/L Programming Manual (MELSAP-L)
Programming methods, specifications, and functions for SFC (MELSAP-L) programs
(Sold separately)
SH-080076
(13JF61)
MELSEC-Q/L/F Structured Programming Manual (Fundamentals)
Methods and languages for structured programming
(Sold separately)
SH-080782ENG
(13JW06)
MELSEC-Q/L Structured Programming Manual (Common Instructions)
Specifications and functions of common instructions, such as sequence instructions, basic instructions, and
application instructions, that can be used in structured programs
(Sold separately)
SH-080783ENG
(13JW07)

9
TERMS
Unless otherwise specified, this manual uses the following terms.
Instructions are written in three programming languages:
ladder diagram for Simple projects, structured ladder/FBD and structured text language for Structured projects. To write
instructions other than comparison operation instructions in the structured ladder/FBD or structured text language, use "_"
instead of ".".
For the comparison operation instructions, use the following instruction symbols.
Term Description
QnPHCPU A generic term for the Q02PHCPU, Q06PHCPU, Q12PHCPU, and Q25PHCPU
QnPRHCPU A generic term for the Q12PRHCPU and Q25PRHCPU
QnUDPVCPU A generic term for the Q04UDPVCPU, Q06UDPVCPU, Q13UDPVCPU, and Q26UDPVCPU
Instruction Ladder diagram Structured ladder/FBD and
structured text language
Comparison operation instruction
S.> S_GT
S.< S_LT
S.= S_EQ
S.>= S_GE
S.<= S_LE

10
CHAPTER 1 OVERVIEW
This manual describes the process control instructions equipped for the CPU module.
1.1 Features
The process control instructions have the following features.
(1) Use of floating-point data
Capable of handling floating-point type real number data, the instructions can perform wide-range and accurate
operations.
(2) Increased efficiency of system adjustment
Micro-blocked process control instructions are combined to perform PID control.
This enables actions to be confirmed on a process control instruction basis, ensuring efficient system adjustment.
Example) Process control instructions used to carry out 2-degree-of-freedom PID control
Microblock
S.PHPL instruction
Process control instruction 1
(Input instruction)
Microblock
S.IN instruction
Process control instruction 4
(Output instruction)
Microblock
S.OUT1 instruction
Process control instruction 3
(2-degree-of-freedom PID
control instruction)
Microblock
S.2PID instruction
Set value (SV)
Process value (PV)
Use each instruction common table.
T0
M0PLS
R0D0
FLT
R1000R200R100
R0 S.IN
R20R100EMOV
R1000R220R120
R20
S.PHPL
R40R120
EMOV
R300R1000R240
R140
S.2PID R40
R60R140EMOV
P1
K1
Execution command
P1CALL
T0RST
FEND
T0
M0
Always executed
R1000R260R160R60S.OUT1
D1R160
INT
Loop tag memory setting
Operation constant setting
Process control instruction 2
(Upper lower limit alarm instruction)
RET

11
1
2
3
4
3
6
7
8
1.1 Features
(3) Free combination of process control instructions for application to a wide range of control
As an option, a process control instruction can be inserted in a loop that links process control instructions.
Add the square root operation instruction (S.SQR) to perform the square root operation of an input signal to provide an
output signal as shown below.
[Example of adding square root operation instruction (S.SQR) to process control instructions]
(4) Automatic detection of various alarms
A system can be configured safely since various alarms are detected automatically in the system.
Regulator
FE flow meter
Liquid
Diaphragm valve
FIC
Operation constant setting
Loop tag memory setting
R300R1000R240R140S.2PID R40
S.2PID instruction
Normal ON
SD1506R200R100R0S.SQR
R100EM0V
Process control instruction
(Square root operation
instruction) S.SQR
instruction
Process control instruction
(2-degree-of-freedom PID
control instruction)
Normal ON
Added as
option
R40

12
(5) PID algorithm using a velocity type incomplete differential format
Partial differential has the following advantages over the complete differential format.
(a) The differential gain is 1/ and the limit value can be set.
(b) The output contains time amplitude, so the system actually responds to the operation edge so the derivative
operation makes the movement valid.
Manipulated
variable
Time(t)
PID
Deviation
DV

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1
2
3
4
3
6
7
8
1.2 PID Control Overview
1.2 PID Control Overview
PID control is applied to the process control of flow rate, speed, air volume, temperature, tension, compounding or like.
In the following application, a value of a control target system can be kept at a set value with PID control.
PID control compares the value measured in the detection section (process value: PV) with the preset value (set value: SV)
and adjust the output value (manipulated value: MV) to eliminate the difference between the process value and set value.
In PID control, proportional operation (P), integral operation (I) and derivative operation (D) are combined to calculate the
manipulated value that will make the process value equal to the set value fast and precisely.
• If the difference between the process value and set value is large, the manipulated value is increased to make it close to
the set value fast.
• When the difference between the process value and set value has reduced, the manipulated value is decreased to make it
equal to the set value slowly and precisely.
1.3 Forward Operation and Reverse Operation
(1) Forward operation is the action that increases the manipulated value when the process value increases more than the
set value.
(2) Reverse operation is the action that increases the manipulated value when the process value is decreasing more than
the set value.
(3) Forward operation and reverse operation make the manipulated value larger as the difference between the set value and
the process value becomes larger.
(4) The following figure shows an example of process control in forward operation and reverse operation.
Process control instructions
are used
SV
PV
PID
operation
Automatic
MV
D/A
converter
module
Controlled
system
Sensor
Set value
Manual
MV
MV
A/D
converter
module
Subdivided (micro-blocked) processings
of PID control
Temperature
Temperature
Time Time
Process value
Process value
Set value
Set value
Forward operation (for air conditioning) Reverse operation (for heating)

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1.4 PID Control Details
This section explains "proportional operation", "integral operation" and "derivative operation" performed for PID control using
the process control instructions.
1.4.1 Proportional operation (P operation)
This section explains the control method using proportional operation.
(1) Proportional operation is the action that compares the deviation (DV, difference between the set value and the process
value) to find the manipulated value (MV).
(2) The proportional term is given by:
MV = KP• DV
KPis a proportional gain constant.
(3) The proportional operation in the case of a step response with a constant deviation will be as follows.
(4) The manipulated value fluctuates between -10 and 110%.
As KPincreases, the manipulated value for the constant deviation also increases.
(5) Offset occurs in proportional operation.
DV
Time
K DV
Deviation
Manipulated value
Time
P

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1
2
3
4
3
6
7
8
1.4 PID Control Details 1.4.2 Integral operation (I operation)
1.4.2 Integral operation (I operation)
This section explains the control method using integral operation.
(1) Integral operation is the operation that continuously changes the manipulated value to eliminate deviation when there is
deviation.
This operation can eliminate the offset that occurs during control performed by a proportional operation.
(2) The time required for adjusting the manipulated value of the integral operation to the manipulated value of the
proportional operation after the deviation is detected is called integral time (TI).
(a) Increasing the integral time decreases the effect of integration.
(It will take time to stabilize.)
(b) Decreasing the integral time increases the effect of integration.
However, since the integral operation will be stronger, hunting may become greater.
(3) The integral operation in the case of a step response with a constant deviation will be as follows.
(4) The integral operation is used as the PI operation that is combined with the proportional operation or as the PID
operation that is combined with the proportional operation and the derivative operation.
Control cannot be carried out by merely performing the integral operation.
K DV
DV
TI
Time
Manipulated value Deviation
Time
Proportional operation integral operation manipulated value
Integral operation manipulated value
Manipulated value in the proportional operation
P

16
1.4.3 Derivative operation (D operation)
This section explains the control method using the derivative operation.
(1) The derivative operation is an operation that adds the proportional manipulated value to the change speed to eliminate
deviation when a deviation has occurred.
The derivative operation can prevent large changes in the object control from disturbances.
(2) The time required for adjusting the manipulated value of the derivative operation to the manipulated value of the
proportional operation after the deviation is detected is called derivative time (TD).
Increasing the derivative time makes the derivative operation stronger.
(3) The derivative operation in the case of a step response with a constant deviation will be as follows.
(4) The derivative operation can be used as PD operation in combination with a proportional operation or as a PID operation
in combination with the proportional operation and integral operation.
Control cannot be carried out by merely performing the derivative operation.
DV
Time
K DV
TD
Time
Manipulated value for proportional operation
Manipulated value Deviation
P

17
1
2
3
4
3
6
7
8
1.4 PID Control Details 1.4.4 PID operation
1.4.4 PID operation
This section explains the control operation using combinations of proportional operation (P operation), integral operation (I
operation), and derivative operation (D operation).
(1) The PID operation controls the calculated manipulated value using (P + I + D) operation.
(2) The PID operation in the case of a step response with a constant deviation will be as follows.
Deviation
Time
Manipulated value
Time
PID operation
I operation
P operation
D operation
PI
operation

18
CHAPTER 2 STRUCTURE AND COMBINATIONS OF
PROCESS CONTROL INSTRUCTIONS
2.1 Structure of Instructions
The instructions that can be used by the process control instructions can be divided into the "instruction part" and "device
part".
The instruction part and device part are as follows.
• Instruction part.......This shows the functions for these instructions.
• Device part.............This shows the data required for operations and the storage destination of the stored operation results.
The device part is classified as the source device and destination device.
(1) Source (S)
The source stores the data used for operation.
(a) In the process control instruction, specify the head device that stores the source data.
(b) Data must have been stored in the specified device until the process control instruction is executed.
(c) Changing the source data allows you to change the data used in that instruction.
(2) Destination (D)
Destination is where the data is stored after operation.
(a) Sets the device for which the data will be stored in the destination.
(b) Depending on the instruction used, data used for operation must also be stored in the destination before start of the
operation.
For the structure of instructions used in structured programs, refer to the MELSEC-Q/L Structured Programming Manual
(Common Instructions).