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Communication operation and setting
(5) Message format types
The message formats corresponding to the function codes in Table 1 on page 225 will be explained.
Read holding register data (H03 or 03)
Can read the description of 1) system environment variables, 2) real-time monitor, 3) faults history, and 4) drive unit
parameters assigned to the holding register area (refer to the register list (page 231))
8 bitsNormal response (Response message)
Query message setting
Description of normal response
1) Slave Address 2) Function
3) Starting
Address
4) No. of Points CRC Check
(8 bits)
H03
(8 bits)
H
(8 bits)
L
(8 bits)
H
(8 bits)
L
(8 bits)
L
(8 bits)
H
(8 bits)
1) Slave Address 2) Function 5) Byte Count 6) Data CRC Check
(8 bits)
H03
(8 bits)
(8 bits)
H
(8 bits)
L
(8 bits)
...
(n16 bits)
L
(8 bits)
H
(8 bits)
Message Setting Description
1) Slave Address
Address to which the message will be sent
Broadcast communication cannot be made (0 is invalid).
2) Function Set H03
3) Starting Address
Set the address at which holding register data read will be started.
Starting Address = Starting register address (decimal)-40001
For example, setting of the Starting Address 0001 reads the data of the holding
register 40002.
4) No. of Points
Number of holding registers from which data will be read
The number of registers from which data can be read is a maximum of 125.
Message Setting Description
5) Byte Count
The setting range is H02 to HFA (2 to 250).
Twice greater than the No. of Point specified at 4) is set.
6) Data: Read data
The number of data specified at 4) is set. Data are read in order of Hi byte and Lo
byte, and set in order of Starting Address data, Starting Address + 1 data,
Starting Address + 2 data,
Example: To read the register values of 41004 (Pr.4) to 41006 (Pr.6) from the slave address 17 (H11)
Query message
Normal response (Response message)
Read value (for frequency setting)
Register 41004(Pr.4): H1770 (60.00Hz)
Register 41005(Pr.5): H0BB8 (30.00Hz)
Slave
Address
Function Starting Address No. of Points CRC Check
H11
(8 bits)
H03
(8 bits)
H03
(8 bits)
HEB
(8 bits)
H00
(8 bits)
H03
(8 bits)
H77
(8 bits)
H2B
(8 bits)
Slave
Address
Function Byte Count Data CRC Check
H11
(8 bits)
H03
(8 bits)
H06
(8 bits)
H17
(8 bits)
H70
(8 bits)
H0B
(8 bits)
HB8
(8 bits)
H03
(8 bits)
HE8
(8 bits)
H2C
(8 bits)
HE6
(8 bits)