Appendix MD280/MD280N User Manual
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Data F003H low order 01H
CRC CHK low order
CRC CHK high order
CRC CHK values are to be calculated
Command code: Command Code˖06Hˈwrite a word.
For example:Write 5000˄1388H˅into F00AH which slave address is 02H.
Master command information
ADDR 02H
CMD 06H
Data addr. high order F0H
Data addr. high order 04H
Data content high order 13H
Data content low order 88H
CRC CHK low order
CRC CHK high order
CRC CHK values are to be calculated
Slave responding information
ADDR 02H
CMD 06H
Data address high order F0H
Data address low order 04H
Data Content high order 13H
Data Content low order 88H
CRC CHK low order
CRC CHK high order
CRC CHK values are to be calculated
3
Cyclical Redundancy Check
In RTU mode, messages include an error-checking field that is based on a
CRC method. The CRC field checks the contents of the entire message.
The CRC field is two bytes, containing a 16-bit binary value. The CRC
value is calculated by the transmitting device, which appends the CRC to
the message. The receiving device recalculates a CRC during receipt of
the message, and compares the calculated value to the actual value it
received in the CRC field. If the two values are not equal, an error results.
The CRC is started by 0xFFFF.Then a process begins of applying
successive eight-bit bytes of the message to the current contents of the
register. Only the eight bits of data in each character are used for
generating the CRC. Start and stop bits, and the parity bit, do not apply to
the CRC.
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