Shihlin electric SDP Series, Manual

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Note: after calculating the CRC error check value, fill in the low byte of the CRC value in the
command message first, and then fill in CRC high byte. Please refer to below example:
Example: read 2 words from the start address 0101H of the servo drive with device number
01H. The last content of the CRC register calculated from ADR to the last byte of the data is
3794H, then the command message is as follows. It should be noted that 94H is sent before
37H.
ADR 01H
CMD 03H
Start data address
01H(high byte)
01H(low byte)
Data quantity
00H(high byte)
02H(low byte)
CRC Check (low byte) 94H(low byte)
CRC Check (high byte) 37H(high byte)
End1 , End0(communication is completed)
Keeping an idle for more than 6mS means communication is completed.
CRC program example:
This function calculates the CRC value in the C language. It needs two parameters:
unsigned char* data;
unsigned char length;
This function will return the CRC value of unsigned integer type.
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++ )