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Appendices
[ 3 ] CRC
To check whether data has been transmitted accurately, the BHT-Ir protocol supports
CRC (Cyclic Redundancy Check) which employs the CRC-16 generating system. In
CRC, a CRC character is suffixed to a sequence of DLE ETX of every transmission block.
Operands for CRC-16
The CRC generates CRC-16 from all bytes of a transmission block excluding DLE SOH
or DLE STX characters (which are at the head of a transmission block), DLE character
of DLE ETX and DLE character of DLE DLE in the text.
CRC operation
The CRC system generates CRC-16 as follows: It multiplies the polynomial formed by
aligning all of the bits starting from the LSB of the first byte to the MSB of the last byte
in a transmission block in descending order, by X16. Next, divide the polynomial by
the generative polynomial X16 + X15 + X2 + 1. The remainder is the value of CRC-16.
Shown below is a data text transmission block and operands for CRC-16 generation.
Serial
number Data text
Operands
Operand
[ 4 ] ID
ID is a 2-digit hexadecimal and designated in 0000h through FFFFh in (2 bytes). 0000h
is assigned to the host computer. Any of 0001h through FFFFh is assigned to the BHT
as follows.
•The system sets an ID when the BHT is initialized.
•You may set an arbitrary ID in System Mode or by using the OUT statement in
BHT-BASIC.
S
T
X
E
T
X
C
R
C
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