Mitsubishi Electric MR-JE-_A Instruction Manual page 28

3. MODBUS PROTOCOL
(2) Usage example
The following shows a setting example of when Modbus registers 2B05h (Command pulse frequency) to
2B07h (Analog torque limit voltage) in the slave address "02" are read.
Index Name
2B05h Command pulse frequency
Analog speed command voltage
2B06h
Analog speed limit voltage
Analog torque limit voltage
2B07h
Analog torque command voltage
Query Message
Slave Address Function
02h 03h
Set the following values to each Query Message.
Message
Slave Address
Function
Starting Address
No. of Points
CRC Check
Response Message
Slave Address Function
02h 03h
The following shows the information in each Response Message.
Message
Slave Address
Function
Byte Count
Data
CRC Check
Data type Read/write
4 bytes Read
2 bytes Read
2 bytes Read
Starting Address
H L
2Bh 05h
Set the station number "02h".
Set "03h".
Set "2B05h", the start address to read.
Set "04h", because the total number of read points from Modbus registers 2B05h to 2B07h is 4.
Data for CRC error check
This data is calculated automatically by a controller.
Byte Count
H L
08h 56h 78h
The station number "02h" is returned.
The value "03h" is returned. This means that the message was received without errors.
The value "08h" is returned. This means that data of 8 frames is returned.
Data starting from the start address is returned.
Lower-bit value of the register 2B05h: "5678h"
Higher-bit value of the register 2B05h: "1234h"
Value of the register 2B06h: "1000h"
Value of the register 2B07h: "2000h"
The endian setting of 4-byte data can be configured using [Pr. PC72]. This example shows the
case when the standard endian (initial value) is set.
Data for CRC error check
This data is calculated automatically by a servo amplifier, and the result of the calculation is
returned.
3 - 5
No. of Points
(Number of read points)
2
1
1
No. of Points
H L
00h 04h
Description
Data
H L H L
12h 34h 10h 00h
Description
Continuous Register value
read/write (Read data)
12345678h
1000h
2000h
CRC Check
L H
(8 bits) (8 bits)
CRC Check
H L L
20h 00h (8 bits) (8 bits)
H