TOHO ELECTRONICS TTM000 - Manual (Page 21)

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6.3 Composition of an RTU request message (transmitted from a high-level computer
to this product)
For codes a) through i), see "6.5 Description of RTU codes."
6.3.1 Composition of a read request message
a) Slave address 1BH
b) Function code 03H
c) Register address
High level 00H
First register address
Low level 00H
d) Number of registers
High level 00H
Fixed at 2
Low level 02H
e) CRC-16
Low level 31H
High level C6H
6.3.2 Composition of a write request message
a) Slave address 03H
b) Function code 10H
c) Register address
High level 00H
First register address
Low level C0H
d) Number of registers
High level 00H
Fixed at 2
Low level 02H
f) Number of data items 04H Number of registers 2
g)
Data for the first register
(a low-level word)
High level 00H ③ When writing ①, ②, ③, and ④
H in the data, write them in the
order described on the left-hand
side. (① represents 1 byte.)
Low level 6FH ④
Data for the first register + 1
(a high-level word)
High level 00H ①
Low level 00H ②
e) CRC-16
Low level 5AH
High level C4H
6.3.3 Composition of a store request message
a) Slave address 03H
b) Function code 10H
c) Register address
High level 02H
First register address
Low level 0EH
d) Number of registers
High level 00H
Fixed at 2
Low level 02H
f) Number of data items 04H Number of registers 2
g)
Data for the first register
(a low-level word)
High level 00H
The data about the storage of settings is
arbitrary.
Low level 00H
Data for the first register + 1
(a high-level word)
High level 00H
Low level 00H
e) CRC-16
Low level FBH
High level 60H