Chapter 9 MODBUS Communication Protocol
Shenzhen Hpmont Technology Co., Ltd.
-62-
HD09 Series User Manual V1.1
9.1.3
MODBUS Protocol Format
MODBUS protocol only supports RTU mode, the corresponding frame format is as follows:
MODBUS uses "Big Endian" encoding, first send high byte, and then low byte.
•
Head and end Frames are defined by the bus idle time of not less than 3.5 bytes.
•
When the slave address is set to 0, it indicates the broadcast address.
•
Data check using CRC-16, the entire information involved in the verification.
9.2
Calibration Relationship of Transfer Value Corresponding
Please refer to the "minimum unit" of the parameter list to determine the calibration relationship of the
function parameters. See the list of the last function parameters of this manual.
Note:
1. F16.05, F16.22 communication data 0 - 2000 corresponds to data -1000- + 1000.
2. In status parameter groups, progress PID feedback (0x332D), process PID error (0x332E), the process PID
integral (0x332F), and the process PID output (0x3330) the communication data 0 - 2000 corresponds to -
1000- + 1000.
9.3
Protocol Functions
9.3.1
Support Functions
MODBUS protocol supports the following functions:
Supported function
Code
Instructions
Read the drive function parameters or status parameters
0x03
Rewrite the inverter with a single function parameter or
control parameter
0x06
Power-down is saved by F17.09
Read the drive function parameters or status parameters
0x10
Power-down is saved by F17.09
Modbus data frame
RTU model
Slave
address
Frame head (at least
3.5 character spacing)
Frame head (at least
3.5 character spacing)
Function
code
Data
Checking