NO.6 Detailed Function Description
68
selection
0: Standard Modbus protocol
1: Dema communication protocol
Dema communication protocol is default; in case of applying standard Modbus protocol,
please contact the manufacturer.
Format of Dema communication protocol
(I) Two modes of communication protocol
RTU mode: Each 8bit data is composed of two hexadecimal characters of 4bit, for example:
64H (hex).
ASCII mode: Each 8bit data is composed of two ASCII characters, for example: 64H (hex) is
expressed in ASCII including 6 (36H) and 4 (34H).
Communication
mode
Start
bit
Data format
Check
End
bit
RTU mode
Mute
ADDR
CMD
LEN
D(n-1)-D(0)
CRC
Mute
ASCII mode
STX
ADDR
CMD
LEN
D(n-1)-D(0)
LRC
END
1. Start bit
Mute: Indicate no Serial port interrupt over 50ms
STX: Start bit ":" (3AH)
2. Data format
ADDR: Communication address (8 bit)
00: MODBUS broadcast mode
01-250: Inverter address
[Note] In case of ADDR=00, no returned data; in case that
ADDR≠00 and is identical to
inverter address, there us response.
CMD: Command code (8bit)
01: Read function code data
02: Alter function code
03: Write command to control inverter state
04: Read current inverter state
05: Set frequency of serial port
LEN: Data length, referring to the length of D (n-1) - D (0), length setting: each 8bit
serves as unit length.
DATA: Data content, D (n-1) - D (0).
3. Check bit