Mitsubishi MELSEC System Q User Manual

6.4 Math Instructions
All the controllers of the MELSEC System Q can perform all four basic arithmetical operations
and can add, subtract, multiply and divide. MELSEC instructions are available for math opera
-
tions with binary values, binary block data, BCD values and character strings.
When you edit your program with GX IEC Developer in Ladder Diagram or IEC instruction list
additional IEC instructions can be used. In this chapter only these IEC instructions are
described. MELSEC instructions are covered in detail in the Programming Manual for the A/Q
series and the MELSEC System Q, art. no. 87431.
The IEC instructions for addition, subtraction, multiplication und division can be applied for the
data types INT (16-bit integer), DINT (32-bit integer) or REAL (floating decimal point values).
Please note that DINT and REAL devices can not assigned directly to these instructions and
must be defined as variables before (see chapter 4.6.2).
6.4.1 Addition
The ADD instruction calculates the sum of two values and writes the result to another device.
쐃
First source device or constant
쐇
Second source device or constant
쐋
Device in which the result of the addition is stored
The example above adds the contents of D0 and D1 and writes the result to D2.
Examples
Add 1,000 to the contents of data register D100:
If you want you can also write the result to one of the source devices. However, if you do this
remember that the result will then change in every
program cycle if the ADD instruction is exe
-
cuted cyclically!
The signs of the values are taken into account by the ADD instruction (e. g. 10 + (-5) = 5).
The data types of the input and output variable of the ADD instruction must be identical. This
can cause problems when the result of the addition exceeds the value range of the variables.
For example, when you add the two integer values (16 bit) "32700" and "100" the result stored
is not "32800" as expected but "-32736" since the maximum value of a 16 bit variable is
"32767". An overflow is interpreted as negative value and will lead to a wrong result.
MELSEC System Q Beginners Manual 6 – 25
More Advanced Programming Math Instructions
Ladder Diagram
IEC Instruction List
LD D0
ADD D1
ST D2






1000
53+
D 100
D 102
1053
18
25
D 0
+
D 0
43

Mitsubishi MELSEC System Q Specifications

General

Category	Programmable Logic Controller (PLC)
Type	Modular
Series	MELSEC
I/O Capacity	Up to 4096 points
Programming Languages	Ladder Logic, Structured Text, Function Block Diagram, Instruction List, Sequential Function Chart
Communication Protocols	Ethernet, CC-Link
Redundancy	Available in certain models
Power Supply	24 V DC, 100-240 V AC (depending on the power supply module)
Operating Temperature	0°C to 55°C
Storage Temperature	-25°C to 75°C
Humidity	5% to 95% (non-condensing)
Shock Resistance	147 m/s2 acceleration, 3 times in each of the X, Y, and Z directions
CPU Type	Various CPUs available (e.g., Q00, Q01, Q02, Q06, Q12, Q13, Q26, Q100, Q172, Q173)

Summary

2 Programmable Logic Controllers

2.2 How PLCs Process Programs

3 The MELSEC System Q

3.1 System Configuration

Details the modular structure and components of the MELSEC System Q.

3.2 Base Units

Describes available base units for mounting MELSEC System Q modules.

3.3 Power Supply Modules

Explains the function and types of power supply modules for MELSEC System Q.

3.4 The CPU Modules

Introduces different types of CPU modules available for the MELSEC System Q.

3.4.2 Memory Organisation

3.5 Digital Input and Output Modules

Describes the types and functions of digital input and output modules.

3.5.1 Digital Input Modules

Explains the specifications and considerations for digital input modules.

3.5.2 Digital Output Modules

Details the types, advantages, and specifications of digital output modules.

3.6 Special Function Modules

Introduces various special function modules for MELSEC System Q automation.

3.6.1 Analog Modules

Explains analog input and output modules and selection criteria.

3.6.2 Temperature Control Modules with PID Algorithm

3.6.3 High-Speed Counter Modules

3.6.4 Positioning Modules

3.6.5 Serial Communication Modules

3.7 Networks and Network Modules

Covers networking concepts and modules for MELSEC System Q communication.

3.7.1 Networking on all Levels

3.7.2 Open Networks

3.7.3 MELSEC Networks

3.7.4 Network Modules

Explains ETHERNET and MELSECNET modules for system communication.

4 An Introduction to Programming

4.1 Structure of a Program Instruction

4.5 Programming Languages

4.6.2 Variables

4.7 The Basic Instruction Set

Provides a reference to basic instructions used in MELSEC PLC programming.

4.7.3 Using switches and sensors

4.7.7 Pulse-triggered execution of operations

4.7.8 Setting and resetting devices

4.8 Safety First!

Emphasizes crucial safety precautions when working with PLCs and systems.

4.9 Programming PLC Applications

Demonstrates PLC application development with a practical example.

4.9.1 A rolling shutter gate

Presents a detailed example of programming a rolling shutter gate control system.

4.9.2 Programming

Guides through the process of creating a new PLC project and assigning variables.

4.9.3 The Hardware

5 Devices in Detail

5.1 Inputs and Outputs

Explains how PLC inputs and outputs connect to the controlled process.

5.1.1 External I/O Signals and I/O Numbers

5.1.2 Inputs and Outputs of the MELSEC System Q

5.2 Relays

Details the function and types of relays (normal and latched) in PLC programs.

5.3 Timers

Describes programmable internal timers, their function, and types (low/high speed, retentive).

5.4 Counters

Explains internal counters for programming counting operations and their features.

5.5 Registers

Covers registers for storing measurements and calculation results (16-bit and 32-bit).

5.5.1 Data registers

Details data registers used for memory storage in PLC programs.

5.5.3 File registers

5.7 Programming Tips for Timers and Counters

5.7.1 Specifying timer and counter setpoints indirectly

5.7.2 Switch-off delay

5.7.3 Delayed make and break

6 More Advanced Programming

6.1 Applied Instructions Reference

Provides a reference for advanced PLC instructions beyond basic logic.

6.1.1 Additional Instructions for Process CPUs

6.2 Instructions for Moving Data

Explains instructions for moving data between registers and devices.

6.2.1 Moving individual values with the MOV instruction

6.2.2 Moving groups of bit devices

6.2.3 Moving blocks of data with the BMOV instruction

6.2.4 Copying source devices to multiple destinations (FMOV)

6.2.5 Exchanging data with special function modules

Details using FROM/TO instructions for data exchange with special function modules.

6.3 Compare Instructions

Explains instructions for comparing values (numerical, string) in PLC programs.

6.4 Math Instructions

Covers basic arithmetic operations like addition, subtraction, multiplication, and division.

6.4.1 Addition

6.4.2 Subtraction

6.4.3 Multiplication

6.4.4 Division

6.4.5 Combining math instructions