Sample ProgramsFP2 Serial Data Unit
8 − 3
8.1 Sample Programs
8.1 Sample Programs
8.1.1 Adding a BCC (block check code)
8.1.1.1 An Overview of the BCC
With serial communication, erroneous data can sometimes occur because of noise or
another factor. With the normal parity check, the data is checked to see if the total number
of “1” bytes in one data element is an even or an odd number, but the BCC (block check
code) can be used for a more sophisticated check.
FP2
Data sending
Received data
BCC
FP1
Sent data
BCC
Sending side
Receiving side
Received data and
BCC are compared,
and contents
checked
BCC is added based on
contents of sent data
SDU
SD RD ERR SD RD ERR AL
COM.1COM.2
COM.1(RS232C)
COM.2(RS232C)
On the sending side, this code is inserted just before the end code and the data is sent.
On the receiving side, the received data is compared with this code, and the data is
checked for reliability.
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