Vicruns VD300 Series, User Manual

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VD300 Series Inverter User Manual Communication Protocol
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times marks the end of the message. A new message can begin after this interval) the entire message
frame must be transmitted as a continuous stream. If a silent interval of more than 1.5 character times
occurs 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-character times following a previous message, the receiving device will
consider it a continuation of the previous message. This will set an error, as the value in the final CRC
field will not be enabled for the combined messages. A typical message frame is shown below.
Frame header START T1-T2-T3-T4(3.5 bits transmission time)
Slave address field ADDR
Communication address: 0~247(decimal) (0 as
broadcast address)
Function field CMD
03H: read slave parameter
06H: write slave parameter
Data field
DATA(N-1)…DATA(0)
2*N bit data: this part is the main content of
communication, also as the core of data exchange
in communication
CRC CHK low bit Detect value: CRC verify bit (16bit)
CRC CHK high bit T1-T2-T3-T4(3.5 bits transmission time)
Frame footer END
END Lo
9.6 Command Code and Communication Data Description
9.6.1 Command code: 03H (0000 0011), reads N words. (There are 16characters can be read at
the most.)
For example: the inverter slave address is 01H, memory start address is 3200H (output frequency
address), read 5bits continuously ( output frequency, set frequency, motor run speed, bus voltage,
output current total 5 data of run parameter), the frame of structure as below:
RTU master command message
START T1-T2-T3-T4
ADDR 01H
CMD 03H
Start address high bit 32H
Start address low bit 00H
Data bit high bit 00H
Data bit low bit 05H
CRC CHK low bit 8BH
CRC CHK high bit 71H
END T1-T2-T3-T4
RTU Master command information
START T1-T2-T3-T4
ADDR 01H