Denso GT20Q-SB User Manual page 83

Note: If the DLE (10h) is included in data other than the header or terminator, the DLE is applied to the front of the
header before the data is transferred. When performing data packing (data packetizing) using a device other than
the communications adapter, the applied DLE must be deleted by CRC calculation and retrieving the transferred
data.
Received packet analysis example
Received data (hexadecimal notation)
10h 02h 00h 11h 00h 00h 31h 32h 33h 34h 35h 36h 37h 38h 0Dh A3h C6h 10h 03h
Data length
Header
(1) Confirm data length.
Data length stored in received data = 0011h = 17 bytes
Data length of received data = 17 bytes
(2) Confirm CRC.
1) Set CRC value to 0.
2) Retrieve the first data byte (00h).
3) Shift CRC value 1 bit to the left.
When there are too many digits due to the shift, XOR the 1021h at the CRC value.
4) Shift the retrieved data 1 bit to the left.
When there are too many digits due to the shift, XOR the 0001h at the CRC value.
5) Repeat the calculations in 3) and 4) 8 times.
6) Retrieve the second data byte (13h).
7) Repeat the calculations in 3) and 4) 8 times.
8) Repeat this calculation up to the final byte.
9) Finally, perform the same calculation on 2 byte CRC storage area (A3h C6h).
Data
-
00h
11h
00h
00h
31h
32h
33h
34h
35h
36h
37h
38h
0Dh
A3h
C6h
(3) If the result of the calculation is 0000h, data has been received successfully.
If the result of the calculation is a value other than 0000h, data has not been received successfully.
Container number
Reserve
CRC
0000h
0000h
1100h
0011h
0108Ah
BD49h
ED78h
CC22h
36DCh
29D7h
941Bh
99C6h
9BA3h
9A0Ah
0CC0h
0000h
Transmission data
CRC
70
Terminator