• ● 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 each module
(Programming by PLC CPU and Motion modules) ]

Lineup

RD78GHV
RD78GHW

• 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
  MR-J5-GMR-J5D-G4MR-JET-G

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

 

RD78G4/RD78G8
RD78G16/RD78G32/RD78G64

• 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
  MR-J5-GMR-J5D-G4MR-JET-G

*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.

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

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Inter-Module Synchronization

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.

Acceleration/Deceleration Methods

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.

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.

Acceleration/deceleration time fixed method

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

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

Synchronous Control

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.

Advanced Synchronous Control FB Settings with Graphic-Based Interface 

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

Clutch 

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
Invalid (Direct coupled operation)	Invalid (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

Restarting synchronous control

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

Cam Data

Linear operation

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

Two-way operation

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

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.

Touch Probe Function

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.

CC-Link IE TSN Safety Communication Function ^*1

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.

*1. Supported by MELSERVO-J5 series.

Engineering Environment

MELSOFT GX Works3

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]

• 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.

• 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.

• 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.

GX Logviewer

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.

Simulation Before an Actual Operation and Monitor Functions that Make Troubleshooting Easy

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.

Security Key Authentication Function

Quick Start Guide

Motion Module Quick Start Guide

Functions List

	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 , 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		1.93
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.