Delta Electronics AC Motor Drive VFD007S23A User Manual page 125

Chapter 5 Parameters|VFD-S Series
Step 5: Repeat step 3 and 4 until eight shifts have been performed. When this is done, a
complete 8-bit byte will have been processed.
Step 6: Repeat step 2 to 5 for the next 8-bit byte of the command message. Continue doing this
until all bytes have been processed. The final contents of the CRC register are the
CRC value. When transmitting the CRC value in the message, the upper and lower
bytes of the CRC value must be swapped, i.e. the lower order byte will be transmitted
first.
The following is an example of CRC generation using C language. The function takes two
arguments:
Unsigned char* data
Unsigned char length
The function returns the CRC value as a type of unsigned integer.
Unsigned int crc_chk(unsigned char* data, unsigned char length){
int j;
unsigned int reg_crc=0xFFFF;
while(length--){
reg_crc ^= *data++;
for(j=0;j<8;j++){
if(reg_crc & 0x01){ /* LSB(b0)=1 */
reg_crc=(reg_crc>>1) ^ 0xA001;
}else{
reg_crc=reg_crc >>1;
}
}
}
return reg_crc;
}
3.5 Address list
The contents of available addresses are shown as below:
Content
AC drive
Parameters
5-70
a pointer to the message buffer
the quantity of bytes in the message buffer
Address
ggnnH gg means parameter group, nn means parameter number, for
example, the address of Pr 4-01 is 0401H. Referencing to
chapter 5 for the function of each parameter. When reading
parameter by command code 03H, only one parameter can be
read at one time.
Functions
Revision August 2006, SE08, SW V2.61