Powtran PI9000-S Series User Manual page 93

will be the address field of a new message. Similarly, if a new message begins
earlier than the interval of 3.5 characters following a previous message, the
receiving device will consider it as a continuation of the previous message. This will
result in an error, because the value in the final CRC field is not right.
RTUframe format :
Frame header START
Slave address ADR
Command code CMD
Data content DATA(N-1)
Data content DATA(N-2)
...........................
Data content DATA0
CRC CHK high-order
CRC CHK low-order
END
CMD (Command) and DATA (data word description)
Command code: 03H, reads N words (max.12 words), for example: for the inverter with slave
address 01, its start address F0.02 continuously reads two values.
Master command information
ADR
CMD
Start address high-order
Start address low-order
Number of registers high-
order
Number of registers low-
order
CRC CHK low-order
CRC CHK high-order
Slave responding information
When F9.05 is set to 0:
ADR
CMD
Byte number high-order
Byte number low-order
Data F002H high-order
Data F002H low-order
Data F003H high-order
Data F003H low-order
CRC CHK low-order
Time interval of 3.5characters
Communication address: 1 to 247
03: read slave parameters；06: write slave parameters
Data content: address of function code parameter, numbers of
function code parameter, value of function code parameter, etc.
value.
Detection Value: CRC
Time interval of 3.5characters
01H
03H
F0H
02H
00H
02H
CRC CHK values are to be calculated
01H
03H
00H
04H
00H
00H
00H
01H
CRC CHK values are to be calculated
89
Appendix II