Goodrive18 series two-in-one VFD Communication
-117-
crc_value=crc_value>>1;
}
}
return(crc_value);
}
In the ladder logic, CKSM uses the table look-up method to calculate the CRC value according
to the content in the frame. The program of this method is simple, and the calculation is fast,
but the ROM space occupied is large. Use this program with caution in scenarios where there
are space occupation requirements on programs.
7.2.3 ASCII mode
A communication protocol uses the hexadecimal system. The mapping
between a hexadecimal number and ASCII number is as follows:
Start bit, 7 or 8 data bits, check bit, and stop bit. The data formats are as
follows:
11-bit character frame:
In ASCII mode, the frame header is ":" ("0*3A"), frame end is "CRLF" ("0*0D" "0*0A") by
default. In ASCII mode, all the data bytes, except for the frame header and frame end, are
transmitted in ASCII code mode, in which four MSB groups will be sent out first and then, four
LSB groups will be sent out. In ASCII mode, the data length is 8 bit. As for "A"–"F", its capital
letters is adopted for ASCII code. The data now adopts LRC checkout which covers slave
address to data information. The checksum equals the complement of the character sum of all
the participated checkout data.
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