4 modbus rtu commands, Fc3 read holding register, Fc4 read input register – VEGA VEGAFLEX 81 Modbus and Levelmaster protocol User Manual
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84
11 Supplement
VEGAFLEX 81 • Modbus and Levelmaster protocol
41828-EN-130314
Register Name
Register Number
Type
Note
TV
2206
DWord
Third Variable in Byte Order BACD (Middle Endian)
QV
2208
DWord
Quarternary Variable in Byte Order BACD (Middle En-
dian)
Unit Codes for Register 104, 108, 112, 116
Unit Code
Measurement Unit
32
Degree Celsius
33
Degree Fahrenheit
40
US Gallon
41
Liters
42
Imperial Gallons
43
Cubic Meters
44
Feet
45
Meters
46
Barrels
47
Inches
48
Centimeters
49
Millimeters
111
Cubic Yards
112
Cubic Feet
113
Cubic Inches
11.4 Modbus RTU commands
FC3 Read Holding Register
With this command, any number (1-127) of holding registers can be read out. The start register,
from which the readout should start, and the number of registers are transmitted.
Request:
Parameter
Length
Code/Data
Function Code
1 Byte
0x03
Start Address
2 Bytes
0x0000 to 0xFFFF
Number of Registers
2 Bytes
1 to 127 (0x7D)
Response:
Parameter
Length
Code/Data
Function Code
1 Byte
0x03
Start Address
2 Bytes
2*N
Register Value
N*2 Bytes
Data
FC4 Read Input Register
With this command, any number (1-127) of input registers can be read out. The start register, from