gefran VDI100 Series Instruction Manual page 295

Node Address
00H: Broadcast to all the drivers
01H: to the No. 01 inverter
0FH: to the No.15 inverter
10H: to the No.16 inverter and so on...., max to No. 31 (1FH)
Function Code
03H: Read the register contents
06H: Write a WORD to register
08H: Loop test
10H: Write several data to register (complex number register write)
Checksum Calculation
LRC
ex. NODE ADDRESS
FUNCTION
COMMAND
+ DATA LENGTH
------------------------------------------
Checksum
CS (H)
CS (L) =
CRC
CRC Check: CRC code covers the content from node address to DATA. Please calculate it according to the
following methods.
(1) Load a 16-bit register with FFFF hex (all1's). Call this CRC register.
(2) Exclusive OR the first 8-bit byte of the message, the low-order byte of the 16-bit CRC register, putting the
result in the CRC register.
(3) Shift the CRC register one bit to the right (toward the LSB), Zero-filling the MSB, Extract and examines the
LSB.
(4) (If the LSB was 0): Repeat Steps (3) (another shift)
(If the LSB was 1): Exclusive OR the CRC register with the polynomial value A001 hex (1010 0000 0000
0001), putting the result in CRC register.
(5) Repeat Steps (3) and (4) until 8 shifts been performed. When this is done, a complete 8-bit byte will be
processed.
(6) Repeat Steps (2) through (5) for next 8-bit byte of the message, Continue doing this until all bytes have
been processed. The final content in the CRC register is the CRC value. When sending the CRC value,
the Low-order byte should be sent firstly, then the High-order byte. For example, CRC value: 1241 Hex, the
high-order byte should be set to 41hex and low-order byte 12hex.
CRC calculate program (C language):
UWORD ch_sum (UBYTE long, UBYTE *rxdbuff )
{
BYTE i = 0;
UWORD wkg = 0xFFFF;
while ( long-- ) {
wkg ^= rxdbuff++;
for ( i = 0 ; i < 8; i++ ) {
if ( wkg & 0x0001 ) {
wkg = ( wkg >> 1 ) ^ 0xa001;
VDI100 • Instruction manual
01H
03H
01H
00H
0AH
0FH ------------ 2's complement
F1H
46H (ASCII)
31H (ASCII)
}
295