Mitsubishi Electric MR-JE-C Series Instruction Manual page 52

4. Modbus RTU
Response Message
Slave Address Function
(8 bits) (8 bits)
Message
Slave Address
Function
Byte Count
Data (Note)
CRC Check
Note. Higher 8 bits of 1-byte data are set to "00h" when this data is returned. To use the signed 1-byte data as 2-byte data, perform sign
extension on the master (controller) side.
(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
2B06h Analog speed command 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
Byte Count
H
(8 bits) (8 bits)
Size
8 bits The station number of a slave (servo amplifier) is returned.
8 bits When the message was received without errors, "03h" is returned.
The Data frame size (in units of bytes) is returned.
8 bits
A value obtained by multiplying the value set for No. of Points in the Query
Message by 2 is returned.
Data starting from the start address specified in the Query Message is returned.
16 bits × n Data is read in order of H (higher bits) and L (lower bits).
Data is read in order starting from the start address.
Data for CRC error check
16 bits
This data is calculated automatically by a servo amplifier, and the result of the
calculation is returned.
Data type Access
I32 ro
I16 ro
I16 ro
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
Data
L to
(8 bits) to (8 bits)
Description
No. of Points
2
1
1
No. of Points
H
00h 04h
Description
Data
H L H L
12h 34h 10h 00h
4 - 7
CRC Check
H L L
(8 bits) (8 bits)
Continuous Register value
read/write (Read data)
12345678h
CRC Check
L L
(8 bits)
CRC Check
H L L
20h 00h (8 bits)
H
(8 bits)
1000h
2000h
H
(8 bits)
H
(8 bits)