Goodrive100 inverters
Communication protocol
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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.
7.3 RTU command code and communication data illustration
7.3.1 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 Max. 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 from0004H 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
