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CMD 0
'3'
'2'
'1'
'0'
'0'
'8'
Starting data
address
'0'
'1'
'0'
'0'
'0'
'0'
'0'
'0'
Number of data
(word/Bit)
'0'
'0'
'2'
'9'
LRC 1
'E'
'D'
LRC 0
'A'
'C'
END 1
CR
CR
END 0
LF
LF
LRC checksum:
LRC check is the added sum from "Address" to "Data content". For example, 01H + 03H + 10+ 00H + 00H + 02H = 16H, then take the
complementary of 2, EAH.
RTU Mode
Read Command
ADR
01H
01H
CMD
03H
02H
10H
08H
Starting data
address
00H
10H
00H
00H
Number of data
02H
09H
(word/Bit)
CRC 1
C0H
BBH
CRC 0
CBH
A9H
CRC (Cyclical Redundancy Check) is obtained by the following steps.
1. Load in a 16-bit register FFFFH as the CRC register.
2. Do an exclusive OR operation of the first byte of the data and low byte of CRC register, and place the operation result back to
the CRC register.
3. Right shift the bits in the CRC register and fill the high bits with "0". Check the removed lowest bit.
4. If the removed lowest bit is "0", repeat step 3. Otherwise, do an exclusive OR operation of the CRC register and the value
A001H and place the operation result back to the CRC register.
5. Repeat step 3 and 4 until the 8 bits (1 byte) are all right shifted.
6. Repeat step 2 and 5 and calcualte all the bits to obtain CRC check.
Please be aware of the high/low byte transmission order in the CRC register.
CMD 0
'3'
'2'
'0'
'0'
Number of data
'4'
'2'
(count by byte)
Start address
'0'
'1'
data
'1'
'7'
1000H/081xH
'F'
'0'
'4'
'1'
'0'
'0'
Address data
1001H
'0'
'0'
LRC 1
'0'
'E'
LRC 0
'3'
'3'
END 1
CR
CR
END 0
LF
LF
Read Command Response
ADR
01H
01H
CMD
03H
02H
Number of data
04H
02H
(count by byte)
Start address
01H
17H
data
F4H
01H
1000H/081xH
03H
Address
data1001H
20H
CRC 1
BBH
77H
CRC 0
15H
88H
CMD 0
'6'
'5'
'1'
'0'
'0'
'8'
Starting data
address
'0'
'1'
'1'
'0'
'0'
'F'
'3'
'F'
Data content
'E'
'0'
'8'
'0'
LRC1
'F'
'E'
LRC 0
'D'
'3'
END 1
CR
CR
END 0
LF
LF
Write Command
ADR
01H
01H
CMD
06H
05H
10H
08H
Starting data
address
01H
10H
03H
FFH
Data content
20H
00H
CRC 1
DDH
8FH
CRC 0
E2H
9FH
CMD 0
'6'
'5'
'1'
'0'
'0'
'8'
Starting data
address
'0'
'1'
'1'
'0'
'0'
'F'
'3'
'F'
Data content
'E'
'0'
'8'
'0'
LRC1
'F'
'E'
LRC 0
'D'
'3'
END 1
CR
CR
END 0
LF
LF
Write Command Response
ADR
01H
01H
CMD
06H
05H
10H
08H
Starting data
address
01H
10H
03H
FFH
Data content
20H
00H
CRC 1
DDH
8FH
CRC 0
E2H
9FH
22
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