EM15 User’s Manual
Appendix I
119
Target
station
address
Read the
command
(0x83)
Error type
CRC
correction and
L
……
H
Free
>3.5Byte
1Byte
1Byte
1Byte
2Byte
Calculate CRC
correction
Slave reads and
response error
frame
Free
(Start frame)
Target
station
address
Write the
command
(0x86)
Error type
CRC
correction and
L
……
H
Free
>3.5Byte
1Byte
1Byte
1Byte
2Byte
Calculate CRC
correction
Slave writes and
response error
frame
Free
(Start frame)
Error types
：
01-Command code error
02-Address error
03-Data error
04-Command cannot to process
RTU frame format
Frame start (START)
More than the 3.5- character time
Slave address(ADR)
Communication address:1 to 247(0: broadcast address)
Command code(CMD)
03: Read slave parameters
06: Write slave parameters
Function code address(H)
It indicates the external parameter address of frequency inverter in
hexadecimal format;
There are functional code or non-functional code (such as running state
parameter/ running command parameters) type parameters, for details
see the address definition.
During the transmission, high bit is put in the front, and low bit is at the
back.
Function code address(L)
Number of function code(H)
It indicates the number of function code ready by the frame. If it is “1”,
then it indicates that it reads one function code. During the transmission,
high bit is put in the front, and low bit is at the back.
Only one function code can be modified at one time without the field.
Number of function code(L)
Data(H)
It indicates the replying data or the data waiting to write-in. During the
transmission, high bit is put in the front, and low bit is at the back.
Data(L)
END
3.5- character time
Command codes and communication data
Command Code 03H (0000 0011), read N words (can read a maximum of consecutive 12 words).
For example
:
for an inverter with the slave address of 01H, the start address of memory is 1001H, read 5 words
consecutively (Running frequency, DC bus voltage, output voltage, output current, output power), the structure of
the frame is as follows
:
RTU mode: Command Message of the Master
START
T1-T2-T3-T4
ADDR
01H
CMD
03H
