Delta PG-40 Specifications download pdf (Page 97)

VFD-B Series

5-62

Step 3: Examine the LSB of CRC register.

Step 4: If the LSB of CRC register is 0, shift the CRC register one bit to the right with

MSB zerofilling, then repeat step 3. If the LSB of CRC register is 1, shift the

CRC register one bit to the right with MSB zerofilling, Exclusive OR the CRC

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

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  a pointer to the message buffer

Unsigned char length  the quantity of bytes in the message buffer

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:

1 2 ... 92 93 94 95 96 97 98 99 100 101 102 ... 178 179

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Delta PG-40 Specifications Page 97