Fc4 read input register, Fc6 write single register, Fc8 diagnostics – VEGA VEGAPULS SR 68 Modbus and Levelmaster protocol User Manual
Page 75
75
10 Supplement
VEGAPULS SR 68 • Modbus and Levelmaster protocol
41371-EN-130624
Parameter
Length
Code/Data
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.
Request:
Parameter
Length
Code/Data
Function Code
1 Byte
0x06
Start Address
2 Bytes
0x0000 to 0xFFFF
Number of Registers
2 Bytes
Data
Response:
Parameter
Length
Code/Data
Function Code
1 Byte
0x04
Start Address
2 Bytes
2*N
Register Value
2 Bytes
Data
FC8 Diagnostics
With this function code different diagnostic functions can be triggered or diagnostic values read out.