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Goodrive300-LIFT series inverter
Communication protocol
-119-
{
if(crc_value&0x0001)
crc_value=(crc_value>>1)^0xa001;
else
crc_value=crc_value>>1;
}
}
return(crc_value);
}
In ladder logic, CKSM calculated the CRC value according to the frame with the table inquiry. The
method is advanced with easy program and quick calculation speed. But the ROM space the program
occupied is huge. So use it with caution according to the program required space.
10.4
RTU command code and communication data illustration
10.4.1 Command code
:
03H
03H(correspond to binary 0000 0011),read N words(Word)(the Max. continuous reading is 16
words)
Command code 03H means that if the master read data form the inverter, the reading number
depends on the "data number" in the command code. The maximum continuous reading number is 16
and the parameter address should be continuous. The byte length of every data is 2 (one word). The
following command format is illustrated by hex (a number with "H" means hex) and one hex occupies
one byte.
The command code is used to read the working stage of the inverter.
For example, read continuous 2 data content from 0004H from the inverter with the address of 01H
(read the content of data address of 0004H and 0005H), the frame structure is as below:
RTU master command message (from the master to the inverter)
START
T1-T2-T3-T4 (transmission time of 3.5 bytes)
ADDR
01H
CMD
03H
High bit of the start bit
00H
Low bit of the start bit
04H
High bit of data number
00H
Low bit of data number
02H
Low bit of CRC
85H
High bit of CRC
CAH
END
T1-T2-T3-T4 (transmission time of 3.5 bytes)
T1-T2-T3-T4 between START and END is to provide at least the time of 3.5 bytes as the leisure time