Function Codes; List Of Function Codes; Read Holding Registers (Reading Data In Holding Registers: 03H) - Mitsubishi Electric MR-JE-C Series Instruction Manual

3. Modbus/TCP

3.6 Function Codes

3.6.1 List of function codes

The MR-JE-_C servo amplifier supports the following function codes.
Code Function name
03h Read Holding Registers
08h Diagnostics
10h Preset Multiple Registers

3.6.2 Read Holding Registers (Reading data in holding registers: 03h)

Data in consecutive registers is read for the specified number of data points starting from the specified
register address.
(1) Message frame
Query Message
Transaction Protocol
Length Field
Identifier Identifier
16 bits 0000h
Message field
Transaction Identifier
Protocol Identifier
Length Field
Unit Identifier
Function
Starting Address (Note)
No. of Points
Note. Registers can be classified into two types: registers that can be continuously accessed and particular registers that cannot be
continuously accessed.
To read particular registers, read only the target registers.
For the details on whether the target registers can be continuously accessed or not, refer to chapter 7.
Reading data in holding registers
The data in the registered holding registers can be read from the client.
Function diagnostics
When this function code is sent from the client to a server, the server returns the
received data to the client without any changes.
Communication checks can be performed.
Writing data in multiple holding registers
Consecutive multiple data sets can be written in the registered holding registers from
the client.
Unit
Function
Identifier
0006h FFh 03h
Size
16 bits Set any value.
16 bits Set "0000h".
16 bits Set "0006h".
8 bits Set "FFh".
8 bits Set "03h".
16 bits Set a start address of the holding registers to read.
16 bits Set the number of points of data to read starting from the start address of the
holding registers from which data is read.
Set the number of read points described in the list of holding registers.
To read the data in continuous registers, set a value obtained by adding the
number of read points of the target registers to this number.
Description
Starting Address
H L H
8 bits 8 bits 8 bits
Description
3 - 4
No. of Points
L
8 bits