Chapter VII Modbus Communication Agreement High Performance Universal FrequConverter User Manual
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The Modbus message includes the start sign, the RTU message, and the end sign.
The RTU message includes the address code, PDU, and CRC check. The PDU includes the command code and
the data section.
The Data Frame field description:
Frame Start START
Idle with more than a 3.5-character transfer time.
From the station
address, AD D R
Communication address range: 1~247 slave address, 0 is the broadcast
address.
command code CMD
command
code
description
0x03
Read multiple registers.
0x06
Write a single register to the frequency converter.
0x10
Write multiple registers to the frequency converter.
data
It mainly includes register address, register number and register content,
etc. For the specific format, see A.4 Chapters.
CRC L
CRC16 check value. When transmitting, low bytes in front and high bytes
after.
CRC H
Frame-end END
Idle with more than a 3.5-character transfer time.
A.4. Command code interpretation
A.4.1 Command code 0x03 reads multiple registers (supports 16 consecutive addresses)
ask PDU
device address
1 Bytes
0x01
command code
1 Bytes
0x03
start address
Two bytes
0x0000~0X FFFF (high 8-bit address at first)
Number of registers
Two bytes
0x0001~0x0010 (1~16, high 8 bits in front)
CRC check code
Two bytes
respond PDU
