Modbus/Tcp 3- 1 To; Outline; Communication Specifications - Mitsubishi Electric MR-JE-C Series Instruction Manual

3. Modbus/TCP
3. Modbus/TCP

3.1 Outline

The Modbus protocol, developed for programmable controllers by Modicon Inc., has evolved into the
Modbus/TCP protocol for use over TCP/IP.
The Modbus master acts as a TCP client, and the Modbus slave acts as a TCP server for client-server
communication. Using the functions in the message frames enables to read or write data from/to
parameters, write input commands, and check operation status of servo amplifiers.
For MR-JE-_C servo amplifier, Modbus registers are assigned like the address assignment of CiA 402 drive
profile.
A Modbus-compatible controller, the client, can communicate with the MR-JE-_C servo amplifiers that are
servers by accessing assigned holding registers.

3.2 Communication specifications

Function
Communication protocol
Conformed standard
Port No.
IP address
Subnet mask
Message format
Physical layer
Communication connector
Communication cable
Network topology
Variable communication speed
Transmission speed between stations
Waiting time setting
Maximum number of connections
Number of request messages that are
Server function
receivable simultaneously
POINT
Modbus/TCP is available with servo amplifiers with software version A3 or later.
The following are shown in the "Data Type" in this instruction manual.
I8 or U8: 2 bytes
I16 or U16: 4 bytes
I32 or U32: 8 bytes
VS: VISIBLE STRING
The following are shown in the "Access" in this instruction manual.
"ro": Only reading is available.
"wo": Only writing is available.
"rw": Reading and writing are available.
Modbus/TCP protocol
OPEN Modbus/TCP SPECIFICATION
No. 502
IPv4 range: 0.0.0.0 to 255.255.255.255
Use the same network address for both a client and servers.
Default value: 192.168.3.0
Default value (recommended): 255.255.255.0
Refer to section 3.3 to 3.5.
100BASE-TX
RJ45, 1 port (CN1)
CAT5e, shielded twisted pair (4 pair) straight cable
Star
100 Mbps
Max. 100 m
None
3
1
3 - 1
Description