Appendix
82VFD700 AC Drive Getting Started Guide
Communication mode
VFD700 uses Modbus RTU, which supports to read/write with normal registers. The
frame has the following basic format:
Start (
With a minimum silent
period of 3.5 character times)
Slave
address
Code
Data
Check code
MODBUS data frame
End (
With a minimum silent
period of 3.5 character times)
A-figure 1-3 ModbusRTU message format
ModbusRTU uses byte type of "big-endian" to state address and data (except the CRC,
which is "little-endian"), and it sends high byte firstly, then low byte.
The frame is terminated with a minimum silent period of 3.5 character times at start and
end. Use CRC-16 to check the message information.
Function codes
The function code determines the different requests.
A-table 1-1 Function code
Code (Hex)
Description
03H
Read multiple registers
06H
Write single register, value changes cannot be saved when drive is
powered off
10H
Write multiple registers, value changes cannot be saved when drive
is powered off
17H
Read and write multiple registers, value changes cannot be saved
when drive is powered off
Parameter mapping
The Modbus register address of every parameter is listed in the last column of Parameter
list in this manul for user’s reference.
The mapping rules between parameter number and register address is as below:
Register address (hexadecimal): MNH
M= decimal convert to hexadecimal from "m"
N= decimal convert to hexadecimal from "n"
"m" and "n" calculation is as below, take parameter Px.y for example,
x.y*100=m*256+n+1
For example:
Modbus register address of parameter P04.01
