79
Modbus RTU control (RS-485 communication)
z
Query
Field name Data Description
Slave address 01h Slave address 1
Function code 17h Read/write of multiple holding registers
Data
(Read) Register address value (upper) 13h
Register address to start reading from
(Read) Register address value (lower) 0Ch
(Read) Number of registers (upper) 00h
Number of registers to be read from the starting register address
(4 registers=0004h)
(Read) Number of registers (lower) 04h
(Write) Register address value (upper) 04h
Register address to start writing from
(Write) Register address value (lower) 80h
(Write) Number of registers (upper) 00h
Number of registers to be written from the starting register address
(4 registers=0004h)
(Write) Number of registers (lower) 04h
(Write) Number of data bytes 08h Value of twice the number of (Write) registers in the query
Value write to register address (upper) 00h
Value written to register address 0480h
Value write to register address (lower) 00h
Value write to register address +1 (upper) 01h
Value written to register address 0481h
Value write to register address +1 (lower) F4h
Value write to register address +2 (upper) 00h
Value written to register address 0482h
Value write to register address +2 (lower) 00h
Value write to register address +3 (upper) 09h
Value written to register address 0483h
Value write to register address +3 (lower) C4h
Error check (lower) CCh
Calculation result of CRC-16
Error check (upper) B4h
z
Response
Field name Data Description
Slave address 01h Same as query
Function code 17h Same as query
Data
(Read) Number of data bytes 08h Value of twice the number of (Read) registers in the query
(Read) Value read from register address (upper) 00h
Value read from register address 130Ch
(Read) Value read from register address (lower) 00h
(Read) Value read from register address +1 (upper) 01h
Value read from register address 130Dh
(Read) Value read from register address +1 (lower) F4h
(Read) Value read from register address +2 (upper) 00h
Value read from register address 130Eh
(Read) Value read from register address +2 (lower) 00h
(Read) Value read from register address +3 (upper) 00h
Value read from register address 130Fh
(Read) Value read from register address +3 (lower) 32h
Error check (lower) E4h
Calculation result of CRC-16
Error check (upper) 46h
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