Shihlin SDH Series, Руководство пользователя

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155
Chapter 9.
End1
、
End0
（
data packet ended
）
Use ’\r’
『
carriage return
』
of “0Dh” and ’\n’
『
new line
』
of “0Ah” to denote the end of communication data packet.
RTU mode
Coding signification
Data are expressed in hexadecimal characters. For example, 1-byte is expressed as data 62H. Data packet structure
Bit sign Name Description
STX Start To keep an idle more than 6mS
ADR Device number 1 byte
CMD Command code 1 byte
DATA(n-1)
Data code n-word = 2n-byte
，
n<=29 ………
DATA(0)
CRC Command code 1 byte
End End code To keep an idle more than 6mS
STX (Communication start)
To keep an idle more than 6mS.
ADR (Communication address)
The address code is from 1 to 32. For example ， number “18” is expressed as ADR=12H.
CMD and DATA
The DATA are varied according to different Command codes.
Command code used as commonly follows
:
Example 1: Command code: 03h, read data
The biggest N id29. Example ： to read 2 words which start address is 0200h from device number 01H is described
below.
Command(host)
：
Response(slave)
：
Example 2
，
Command code:06H
，
write data (1 word)
Example
：
to write “100”
（
0064H
）
into the drive which device number 01H and start address 0200h.
Command(host) ： Response(slave) ：
ADR 01H
CMD 03H
start address
02H(high byte)
00H(low byte)
word length
00H
02H
CRC debug low byte C5H(low byte)
CRC debug high byte B3H(high byte)
ADR 01H
CMD 03H
byte length 04H
content of address
0100H
00H(high byte)
B1H(low byte)
content of address
0101H
1FH(high byte)
40H(low byte)
CRC debug low byte A3H(low byte)
CRC debug high byte D4H(high byte)
ADR 01H
CMD 06H
start address
02H(high byte)
00H(low byte)
word length
00H(high byte)
64H(low byte)
CRC debug low byte 89H(low byte)
CRC debug high byte 99H(high byte)
ADR 01H
CMD 06H
start address
02H(high byte)
00H(low byte)
word length
00H(high byte)
64H(low byte)
CRC debug low byte 89H(low byte)
CRC debug high byte 99H(high byte)