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Fc4 read input register, Fc6 write single register, Fc8 diagnostics – VEGA VEGAPULS SR 68 Modbus and Levelmaster protocol User Manual

Page 75

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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.