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MELSEC iQ-R Series

PLCopen(R) Motion Control FB Mode

Features of PLCopen(R) Motion Control FB Mode
  • Supports ST language for programming while a PLC CPU supports ladder, FBD/LD, and ST language.
  • Utilizes the library of PLCopen® Motion Control FBs, which are compliant with international standards, for programming.
  • Enables users to analyze the operation status with logging data on GX LogViewer, improving debug efficiency.

[An example of programming by PLC CPU
(Programming by PLC CPU only) ]

[An example of programming by PLC CPU
(Programming by PLC CPU only) ]

[An example of programming by each module
(Programming by PLC CPU and Motion modules) ]

[An example of programming by each module
(Programming by PLC CPU and Motion modules) ]



MELSEC iQ-R series

  • Maximum number of control axes:
    128 axes/module (RD78GHV)
    256 axes/module (RD78GHW)
  • Minimum operation cycle *1:
    31.25 [μs]
  • ST language program capacity:
    Built-in ROM max. 64 MB + SD memory card
  • Compatible servo amplifiers

*1. The operation cycle varies by the number of
control axes and the models.


RD78G4/ RD78G8 RD78G16/ RD78G32 RD78G64

MELSEC iQ-R series

  • Maximum number of control axes:
    64 axes/module (RD78G64)
  • Minimum operation cycle *1:
    62.5 [μs]
  • ST language program capacity:
    Built-in ROM max. 16 MB
    + SD memory card
  • Compatible servo amplifiers

*1. The operation cycle varies by the number of
control axes and the models.


Improved Performance

The minimum operation cycle of RD78GH in PLCopen® motion control FB mode is approximately 4.1 to 6.2 times faster than that of the previous models, and the number of maximum control axes is 4 to 8 times more. The data from the servo amplifiers and input/output signals can be received at high speeds, which reduces the cycle time.

Improved Performance

Minimum operation cycle 31.25μs Max number of control axes 256axesIndustry leading level

*1. The values are applicable when RD78GH is used.

Improved Performance

Inter-Module SynchronizationPLCopen(R)

The inter-module synchronization function can synchronize the control timings among multiple Motion modules on the same base unit.

  • A CPU and each I/O module are synchronized, and thus the I/O signals from different machines can be synchronized.
  • The control load can be distributed among the PLC CPU and the Motion modules, and therefore the number of axes can be increased without sacrificing performance.

Inter-Module Synchronization

Acceleration/Deceleration MethodsPLCopen(R)

Three types of acceleration/deceleration methods are available: trapezoidal acceleration/deceleration, jerk acceleration/deceleration, and acceleration/deceleration time fixed.

Trapezoidal acceleration/deceleration

After starting, maximum acceleration is maintained until the target
speed is reached.
For example, when a vehicle loaded with a workpiece accelerates
suddenly, the workpiece will swing back and forth due to the
impact of the sudden acceleration.
To reduce impacts and vibrations in a case such as this, the
vehicle must accelerate at a slower rate.
The speed creates a trapezoidal shape.

Trapezoidal acceleration/deceleration
Jerk acceleration/deceleration

The acceleration changes gradually.
For example, when a vehicle loaded with a workpiece accelerates
gradually, the load will not swing back and forth after acceleration.
The jerk is maintained during acceleration. When the vehicle has
almost reached the target speed, the jerk is decelerated. Adjusting
jerk in this way achieves smooth acceleration/deceleration while
also shortening the time it takes to reach the target speed.
The speed creates a S-curve shape.

Jerk acceleration/deceleration
Acceleration/deceleration time fixed method

This method executes acceleration/deceleration based on the
time specified, regardless of the commanded speed.

Acceleration/deceleration time fixed method

*1. Input acceleration.
*2. Specify acceleration time.

Synchronous ControlPLCopen(R)

Flexibly Combining Synchronous Control FBs

Synchronous control is performed using function blocks that operate as software-based mechanical modules such as gear, shaft, speed change gear, and cam.

  • The number and the combination of the synchronous modules are flexibly selected, achieving optimized operation.
  • The following two types of cam data are available: cam data and cam data for a rotary knife
  • Complex cam control is possible by flexibly switching cams.
  • Positioning and synchronous control can be performed together in the same program.
  • Cam for a rotary knife can be easily created in MELSOFT GX Works3 or by using function blocks.
  • Synchronous control using a synchronous encoder is possible. *1

*1. Supported by MELSERVO-J5 series.

An example of packing machine program (FBD)

Advanced Synchronous Control FB Settings with Graphic-Based Interface NEW

In addition to PLCopen® Motion Control FB, the advanced synchronous control data can be used in the program. The advanced synchronous control can be easily executed by setting the auxiliary shaft, gear, clutch, and speed change gear with the advanced synchronous control data (parameters) and starting the synchronous control.

  • Set the auxiliary shaft, gear, clutch, and speed change gear with a parameter
  • The enabled synchronous module images are highlighted, allowing easy confirmation of set data through visualization
  • Cam control can be easily executed by creating cam data and setting parameters
Advanced synchronous control data
Advanced synchronous control data
  • Input axis data
  • Synchronous parameter (output axis)
  • Auxiliary shaft data
  • Clutch data
  • Gear data
  • Speed change gear data
  • Cam data (operation profile)
  • Cam waveform type

Clutch NEWS

The clutch is used to transmit/disengage command pulses from the main/auxiliary shaft input side through turning the clutch ON/OFF, which controls the operation/stop of the output axis.
The clutch can be set to the main shaft clutch and the auxiliary shaft clutch.

Clutch ON control mode Clutch OFF control mode
(Direct coupled operation)
(OFF control invalid)
Clutch command Clutch command
(One-shot operation)
Clutch command leading edge Clutch command leading edge
Clutch command trailing edge Clutch command trailing edge
Address mode Address mode
I/O data specification I/O data specification

Advanced synchronous control data

Acceleration/Deceleration Methods
Acceleration/Deceleration Methods

Restarting synchronous control NEW

In case that the synchronous positions become misaligned after an emergency stop, etc., new synchronous positions are calculated from each axis position, and then the synchronous control can be restarted at the specified positions.

  1. In synchronous control analysis mode, the cam commanded current positions of each output axis (axis1, 2, and 3) are updated based on the current position per cycle of the input axis.
  2. The output axes perform positioning to the updated cam commanded current positions.
  3. Turn OFF the synchronous control analysis mode, and turn ON the axes to start synchronous control.

Synchronous Encoder *1

The Motion module easily performs synchronous control by setting a synchronous encoder to "Real encoder axis" and creating a program with function blocks.
The number of command pulses can be adjusted using the function block (MC_Gearin) or a parameter.

Synchronous Encoder

*1. Supported by MELSERVO-J5 series.
      The system shows an example using an incremental synchronous encoder.
      When configuring an absolute position system, use an encoder of HK series servo motors.

Cam Data

Create operation profile data *1 (cam data) according to your application. The created cam data is used to control output axis.
The following three cam operations are available: linear operation, two-way operation, and feed operation. Choose one according to your application.

*1. "Operation profile data" is a general name for waveform data, which is used for various applications.

Operation Profile Data (Cam Data)
Linear operation

The cam pattern is a linear line.
This pattern is used for a ball screw and a rotary table.

Linear operation
Two-way operation

The beginning and the end of the cam pattern are the same.
Mechanical cams fall into this category.

Two-way operation
Feed operation

The beginning and the end of the cam pattern differ.
This pattern is used for fixed-amount feed operations and intermittent operations.
Set the end point for the feed operation to a position of your choice.

Feed operation

Touch Probe FunctionPLCopen(R)

This function latches data responding to a trigger signal input to a servo amplifier.
The compensation amount is calculated based on the latched data, and the error is compensated using a compensation axis.
A high-accuracy touch probe at 1 μs is available.

Touch Probe Function

Servo System RecorderPLCopen(R)

The Motion module automatically collects data of all real drive axes when an error occurs. The collected data, such as the command and the feedback values, greatly helps you analyze the error cause.

  • Automatic collection of data, such as the command and feedback values, without programming
  • Data collection of all axes, which helps you locate the error cause even when the error is caused by the other axes without an error

Data collection

GX LogViewer

The collected data of the Motion module is displayed on GX LogViewer.
The operation status before and after an error is displayed in waveform, which allows you to analyze more operation details and helps you locate the error cause.

GX LogViewer

icon zoom


  • Displays the collected data and events graphically.
  • Enables users to adjust a graph easily by automatic adjustment function and drag operation.

CC-Link IE TSN Safety Communication Function *1PLCopen(R)

CC-Link IE TSN enables control of safety and non-safety communications realizing a flexible system whereby safety communications can be easily incorporated into the main control network.
In the following system which integrates safety and non-safety communications, the safety CPU checks the safety signals received via the safety remote I/O module and outputs the safety signals (STO, etc.) to the servo amplifiers. Outputting safety signals via the network eliminates the need for wiring of safety signals to a safety controller and a servo amplifier.

CC-Link IE TSN Safety Communication Function

*1. Supported by MELSERVO-J5 series.

Engineering EnvironmentPLCopen(R)


MELSOFT GX Works3 has a variety of features which help users create programs and conduct maintenance more flexibly and easily.
This software includes motion control setting to support all Motion module development stages - from setting parameters to programming, debugging, and maintenance.


Network Configuration Settings

[Network configuration settings]

  • Intuitive network settings with drag-and-drop operations and a graphical screen view

[Automatic detection]

  • By clicking the [Connected/Disconnected Module Detection] button, the connection status of device stations is automatically detected and the CC-Link IE TSN configuration screen is generated.

Automatic detection

Easy Programming Through Structured Text Language
  • Structured text programs are composed of function blocks, increasing program readability.
  • Modularization of the programs increases their reusability.
  • The consistent, common operability on a single engineering tool improves usability further.
  • A wide selection of programming elements in the MELSOFT Library contributes to reducing programming time.
  • The program is created by dragging & dropping programming elements, which simplifies the programming process.
  • A startup time is reduced using the simulator of MELSOFT GX Works3 that can debug a program without an actual machine.

Easy Programming Through Structured Text Language

Programming Using Labels
  • The control axes of the Motion modules and I/O signals are defined as label variables, which enables easy reuse of programs and helps to improve programming efficiency.
  • The global labels created in the Motion module project can be used in PLC CPUs.

Programming Using Labels

GX LogviewerPLCopen(R)

The graph data of both PLC CPU modules and Motion modules can be viewed on a single tool, GX LogViewer. This tool helps you efficiently analyze data from two different modules. The following two functions are provided for logging: data logging function (offline) and real-time monitor.

Data Logging Function (Offline)

Data Logging Function (Offline)

The function performs data logging by a specified time interval based on the logging setting (trigger condition, data collection) written to the motion system from the engineering tool. The results are saved as a data logging file.
Up to 10 data settings can be simultaneously logged for the motion system.

Real-time monitor

Up to 32 collected motion system data can be displayed in real time.

Real-time monitor

Simulation Before an Actual Operation and Monitor Functions that Make Troubleshooting EasyPLCopen(R)

The system simulator enables the Motion module and PLC CPU programs to be simulated interactively.
A program operation can be checked without an actual machine during debugging process, which shortens the startup time.

GX Simulator3

Security Key Authentication Function NEW PLCopen🄬PLCopen(R)

Security Key Authentication Function

The security key authentication prevents programs from being opened on personal computers where the security key has not been registered. Furthermore, because programs can be executed only by Motion modules with the security key registered, the integrity of customer technologies and other intellectual property is not compromised.

Quick Start GuidePLCopen(R)

Functions ListPLCopen(R)

  Motion Module
RD78GHW RD78GHV RD78G64 RD78G32 RD78G16 RD78G8 RD78G4
Maximum number of control axes 256 128 64 32 16 8 4
Minimum operation cycle [μs] *1 31.25 62.5
Servo amplifier connection method CC-Link IE TSN (Communications speed: 1 Gbps/100 Mbps)
Connectable servo amplifier MR-J5-G, MR-J5W-G, MR-J5D-G4     More details
MR-JET-G     More details
Maximum distance between stations [m(ft.)] 100(328.08)
Control modes Position control, Speed control, Torque control, Synchronous control, Cam control
Positioning control Position control, Linear interpolation (Up to 4 axes), Circular interpolation (2 axes)
Acceleration/deceleration process Trapezoidal acceleration/deceleration, Jerk acceleration/deceleration,
Acceleration/deceleration time fixed method
Programming language PLC CPU: Sequence program, FBD/LD, ST
Motion module: ST
Home position return Driver home position return *2
Manual control JOG operation
Auxiliary functions Forced stop, Hardware stroke limit, Software stroke limit, Absolute position system,
Data logging, Acceleration/deceleration time change,
Inter-module synchronization, Security Key Authentication Function NEW,
Target position change, Torque limit value change, Speed change, Override,
CC-Link IE TSN safety communication function *3
Common functions Touch probe, Axis emulate, Event history, Monitoring of servo data,
Servo system recorder, Inter-module synchronization
Engineering environment MELSOFT GX Works3
Number of I/O occupying points 32 points + 16 points (empty slot) 32
5VDC internal current consumption [A] 2.33
Mass [kg] 0.44 0.26
  • *1. The minimum operation cycle varies depending on the number of control axes and the model.
  • *2. The home position return method set in a driver (a servo amplifier) is used.
  • *3. Supported by MELSERVO-J5 series.