4 modbus rtu commands, Fc3 read holding register, Fc4 read input register – VEGA VEGAFLEX 81 Modbus and Levelmaster protocol Coax probe User Manual
Page 77: Fc6 write single register
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11 Supplement
VEGAFLEX 81 • Modbus and Levelmaster protocol
42283-EN-130314
Unit Code
Measurement Unit
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
which the readout should start, and the number of registers are transmitted.
Request:
Parameter
Length
Code/Data
Function Code
1 Byte
0x04
Start Address
2 Bytes
0x0000 to 0xFFFF
Number of Registers
N*2 Bytes
1 to 127 (0x7D)
Response:
Parameter
Length
Code/Data
Function Code
1 Byte
0x04
Start Address
2 Bytes
2*N
Register Value
N*2 Bytes
Data
FC6 Write Single Register
With this function code an individual holding register can be written.