master command message (from the master)
H from
he command means that the master write data and one
to the master for the response of reading
Communication Protocol
133
START
T1-T2-T3-T4 (transmission time of 3.5 bytes)
ADDR
01H
CMD
03H
Byte number
04H
Data high bit of address 0004H
13H
Data low bit of address 0004H
88H
Data high bit of address 0005H
00H
Data low bit of address 0005H
00H
CRC CHK low bit
7EH
CRC CHK high bit
9DH
END
T1-T2-T3-T4 (transmission time of 3.5 bytes)
The meaning of the response is that:
ADDR
= 01H means the command message
with the
address of 01H and ADDR
the
address of 01H and ADDR
occupies one byte
CMD
=03H means the message
to the master for the response of reading
from
command and CMD occupies one byte
"Byte number"
means all byte number from the byte(excluding the byte) to CRC byte(excluding
the byte). 04 means there are 4 byte of data from the "byte number" to "CRC CHK low bit", which
are "digital address 0004H high bit", "digital address 0004H low bit", "digital address 0005H high
bit" and "digital address 0005H low bit".
There are 2 bytes stored in one data with the fact that the high bit is in the front and the low bit is in
the behind of the message, the data of data address 0004H is 1388H, and the data of data address
0005H is 0000H.
CRC occupies 2 bytes with the fact that the high bit is in the front and the low bit is in the behind.
9.4.1.2 Command code: 06H
06H (correspond to binary 0000 0110), write one word (Word)
command can write one data
other than multiple dates.
For example, write 5000 (1388H) to 0004
with the
address of 02H,
the frame
structure is as below:
RTU
START
T1-T2-T3-T4(transmission time of 3.5 bytes)
ADDR
02H
CMD
06H
High bit of write data address
00H
Low bit of write data address
04H
High bit of data content
13H
Low bit of data content
88H
