Vega VEGAPULS 63 - 11 Supplement: Modbus RTU Commands; 11.4 Modbus RTU Commands (FC3, FC4)

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11 Supplement
VEGAPULS 63 • Modbus and Levelmaster protocol
41364-EN-170711
Unit Code Measurement Unit
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.