Appendix Communication Protocol GK600 User Manual
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sends commands using broadcast address, the slave does not respond;
2
）
Native address, baud rate and data format of inverter are set through slave operating
panel or serial communication;
3
）
Slave reports the current fault information in the latest response frame for master polling;
4
）
Drive employs RS-485 interface or extended RS-232 interface.
4. Protocol Format
Modbus protocol supports both RTU and ASCII mode.
RTU data frame format is shown as the figure below:
RTU:
In RTU mode, idle time between frames can be set through function code or comply with
Modbus internal convention, for which the minimum interframe idle is as follows:
1
）
Frame header and end define the frame by making bus idle time equal to or longer
than 3.5-byte time;
2
）
After the start of frame, the clearance between characters must be less than
1.5-character communication time, or the newly received characters will be treated
as the header of the new frame;
3
）
Data check employs CRC-16 and the whole information participates in the check;
the high and low bytes of check sum shall be sent after exchange. Please refer to
examples at the end of protocol for details of CRC check;
4
）
The bus idle time of at least 3.5 characters (or set minimum bus idle time) shall be
maintained between frames and needs not to accumulate the starting and ending
idle time.
The data frame of which the request frame is "reading parameter value of b0-02 from slave
0x01" is as below:
Appendix Table 1
Address
Function code
Register
address
Read words
Check sum
01
03
02 02
00 01
24 72
Response frame of slave 0x01 is as below:
数据
校验
功能码
从机地址
起始
:
至少
3.5
个
字符空闲
结束
:
至少
3.5
个
字符空闲
Modbus
报文
RTU
数据帧格式
RTU data frame format
Modbus message
Start: at
least 3.5 idle
characters
Slave
address
Parameter
Data
Check
End: at least
3.5 idle
characters
