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APPENDIX
A. A
C
B
UTO
AL
UFFER
°C
pH
0
4.00
5
4.00
10
4.00
15
4.00
20
4.00
25
4.005
30
4.015
35
4.025
40
4.03
45
4.045
50
4.06
55
4.075
60
4.085
65
4.10
70
4.13
75
4.14
80
4.16
85
4.18
90
4.21
B.MODBUS RTU R
EGISTER
03 (0
03) R
H
X
EAD
OLDING
This function code is used to read the contents of a contiguous block of holding registers in a remote device.
The Request Protocol Data Unit specifies the starting register address and the number of registers. In the
Protocol Data Unit Registers are addressed starting at zero. Therefore registers numbered 1-16 are address as
0-15.
The register data in the response message are packed as to bytes per register, with the binary contents right
justified within each byte. For each register, the first byte contains the high order bits and the second contains
the low order bits.
Request
Modbus ID (Slave Address)
Function code
Starting Address
Quantity of Registers
CRC
Response
Modbus ID (Slave Address)
Function code
Byte Count
Register Value(s)
T
ABLES
pH
pH
7.115
10.32
7.085
10.25
7.06
10.18
7.04
10.12
7.015
10.06
7.00
10.01
6.985
9.97
6.98
9.93
6.975
9.89
6.975
9.86
6.97
9.83
6.97
6.97
6.98
6.99
7.01
7.03
7.05
7.08
L
ISTING
R
EGISTERS
1 Byte
1 Byte
2 Bytes
2 Bytes
2 Bytes
1 Byte
1 Byte
1 Byte
*N X 2 Bytes
1 to 247 (0x01 to 0xF7)
0x03
0x0000 to 0xFFFF
1 to 125 (0x01 to 0x7D)
calculated
1 to 247 (0x01 to 0xF7)
0x03
2 X N*
44
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