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LRC Check is the value added from Address to Data Content. For example, the
LRC Check of the above 3.3.1 enquiry message is as: 01H + 03H + 21H + 02H +
00H + 02H = 29H, then the complement of2(D7H) is taken.
CRC Check of RTU mode
CRC Check is from Address to Data content, and its running rule is as follows:
Step 1: Make 16-bit temporary storage (CRC temporary storage)= FFFFH.
Step 2: Exclusive OR first 8-bit byte message instruction and low 16-bit CRC
temporary storage: Perform Exclusive OR, and store the result into CRC
temporary storage.
Step3: Move CRC temporary storage one more bit, and fill 0 into high bit
position.
Step 4: Check right shift value, if being 0, store the new value for step 3 into
CRC temporary storage, otherwise in case of Exclusive OR A001H and CRC
temporary storage, store the result into CRC temporary.
Step 5: Repeat Step 3 ~ Step 4, and operate completely for 8-bit. Step
6: Repeat Step 2 ~ Step 5, and take the message instruction for next 8-bit, till all
message instructions are operated completely.
Finally, the value gotten of CRC temporary storage is CRC Check. It is
noteworthy that, CRC Check must be placed into the check mode of message
instruction interchangeably.
The following is the example of CRC Check running written in C language:
Unsigned char * data —//Message instruction pointer Unsigned char length
<—//Length of message instruction unsigned int crc_chk (unsigned char*data,
unsigned char length)
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Chapter 6 Description of parameter setting
FC100 Series User Manaul
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