Delta ASD-A2-0121 Series User Manual page 610

Chapter 9 Communications
CRC (RTU Mode):
The description of CRC is as the followings:
Step 1: Load a 16-bits register of FFFFH, which is called CRC register.
Step 2: (The low byte of CRC register) XOR (The first byte of command), and save
the result in CRC register.
Step 3: Right move one bit. Check the least significant bit (LSB) of CRC register.
If the bit is 1, then (CRC register) XOR (A001H).
Step 4: Return to Step 3 until Step 3 has been executed for 8 times. Go to Step 5.
Step 5: Repeat the procedure from Step 2 to Step 4 until all bytes are processed.
Get the result of CRC value.
Description: After calculating CRC value, fill in the low word of CRC first in command message,
and then fill in the high word of CRC. For example, if the result of CRC algorithm is
3794H, fill in 94H in low word and then 37H in high word, as shown in the following
figure.
ADR
CMD
Starting data address
Number of data
(In Word)
CRC Check Low
CRC Check High
01H
03H
01H (High)
01H (Low)
00H (High)
02H (Low)
94H (Low)
37H (High)
ASDA-A2
9-15