KE300A Inverter MODBUS Communication Protocol
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9.5 Communication Data Structure
MODBUS protocol communication data format of KE300A series inverter is shown as following:
In RTU mode, the Modbus minimum idle time between frames should be no less than 3.5 bytes. The
checksum adopts CRC-16 method. All data except checksum itself sent will be counted into the calculation.
Please refer to section: CRC Check for more information. Note that at least 3.5 bytes of Modbus idle time
should be kept and the start and end idle time need not be summed up to it.
The entire message frame must be transmitted as a continuous data stream. If a idle time is more than 1.5
bytes before completion of the frame, the receiving device flushes the incomplete message and assumes
that the next byte will be the address field of a new message. Similarly, if a new message begins earlier
than 3.5 bytes interval following a previous message, the receiving device will consider it as a continuation
of the previous message. Because of the frame’s confusion, at last the CRC value is incorrect and
communication fault will occur.
RTU frame format:
START
Transmission time of 3.5 bytes
Slave Address
Communication addr. : 0 to 247
Command Code
03H: Read slave parameters
06H: Write slave parameters
DATA (N-1)
Data:
Function code parameter address, the number of
function code parameter, Function code parameter, etc.
DATA (N-2)
……
DATA0
CRC Low byte
Detection Value: CRC value
CRC High byte
END
Transmission time of 3.5 bytes
9.6 Command Code and Communication Data Description
9.6.1 Command code
: 03H, reads N words. (There are 12 characters can be read at the most.)
For example: The inverter start address F002 of the slave 01 continuously reads two consecutive values.
Master command information
Address
01H
Command Code
03H
Start Address High byte
F0H
Start Address Low byte
02H
Register Number High byte
00H
Register Number Low byte
02H
CRC Low byte
56H
CRC High byte
CBH
