ENC EN600PV Series, Руководство пользователя

Страница: 80 / 91

Modbus communication protocol
77
CRC check value high byte
Closing Flag
3.5 characters time pause
Regarding generation method of CRC check value, please refer to check mode Section.
ASCII frame format as the table below:
Frame Header ‘:’ （ 0x3A ）
Slave address Hi Slave address: Combined by 2 ASCII code
Slave address Lo 8 bit slave address 0~247
Command code Hi
Command code: 8 bit command code
combined by 2 ASCII code
Command code Lo
03H:read slave parameter
06H:write slave parameter
Data content DATA The contents of data packet
Data content DATA
N pieces of 8bit data content combined by
2*N pieces of ASCII code
……
……
LRC CHK Hi LRC check value includes 2 pieces of ASCII
code
LRC CHK Lo
Closing Flag Hi
Closing Flag Hi = CR
（
0x0D
）
Closing Flag Lo Closing Flag Lo = LF
（
0x0A
）
A.5.2 Host read slave parameter
Command code 03H. Host can read one or more parameter (up to ten) by initiating a
communication transaction. E.g., read 2 contiguous inverter parameter values from the address
0000H of inverter whose address is 01, the contents of host command:
ADR 01H
CMD 03H
Parameters initial address high byte 00H
Parameters initial address low byte 00H
Number of parameter high byte 00H
Number of parameter low byte 02H
CRC check value low byte C4
CRC check value high byte 0B
The contents of slave reply:
ADR 01H
CMD 03H
Parameter value bytes 04H
Address 0000H content high byte 00H
Address 0000H content low byte 00H
Address 0001H content high byte 00H
Address 0001H content low byte 03H
CRC check value low byte BA
CRC check value high byte F2
ENC