Chapter 9 Communications ASDA-A2
Revision February, 2017 9-15
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 byte is processing. 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.
ADR 01H
CMD 03H
Starting data address
01H (High)
01H (Low)
Number of data
(In Word)
00H (High)
02H (Low)
CRC Check Low 94H (Low)
CRC Check High 37H (High)
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