Powtran PI500-S 022G3 - Page 77

Appendix II
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Appendix II
Byte number high-order
00H
Byte number low-order
04H
Data F002H high-order
00H
Data F002H low-order
01H
Data F003H high-order
00H
Data F003H low-order
01H
CRC CHK low-order
CRC CHK values are to be calculated
CRC CHK high-order
When F9.05is set to 1:
ADR
01H
CMD
03H
Byte number
04H
Data F002H high-order
00H
Data F002H low-order
01H
Data F003H high-order
00H
Data F003H low-order
01H
CRC CHK low-order
CRC CHK values are to be calculated
CRC CHK high-order
Command Code: 06H, write a word. For example: Write 5000(1388H)into the address
F013H of the inverter with slave address 02H.
Master command information
ADR
02H
CMD
06H
Data address high-order
F0H
Data address low-order
13H
Data content high-order
13H
Data content low-order
88H
CRC CHK low-order
CRC CHK values are to be calculated
CRC CHK high-order
Slave responding information
ADR
02H
CMD
06H
Data address high-order
F0H
Data address low-order
13H
Data content high-order
13H
Data content low-order
88H
CRC CHK low-order
CRC CHK values are to be calculated
CRC CHK high-order
II -2 Check mode
Check mode - CRC mode: CRC (Cyclical Redundancy Check) adopts RTU frame format,
the message includes an error-checking field that is based on CRC method. The CRC field
checks the whole content of message. The CRC field has two bytes containing a 16-bit binary
value. The CRC value calculated by the transmitting device will be added into to the message.
The receiving device recalculates the value of the received CRC, and compares the calculated
value to the Actual value of the received CRC field, if the two values are not equal, then there is
an error in the transmission.
The CRC firstly stores 0xFFFF and then calls for a process to deal with the successive eight-
bit bytes in message and the value of the current register. Only the 8-bit data in each character is
valid to the CRC, the start bit and stop bit, and parity bit are invalid.
During generation of the CRC, each eight-bit character is exclusive OR(XOR) with the
register contents separately, the result moves to the direction of least significant bit(LSB), and