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[ 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 X
16
. Next, divide the polynomial by the generative polynomial X
16
+ X
15
+ X
2
+ 1.
The remainder is the value of CRC-16.
Shown below is a data text transmission block and operands for CRC-16 generation.
[ 4 ] ID
ID is a 2-digit hexadecimal and designated in 0000h through FFFFh in (2 bytes). 0000h is assigned to
the host PC. 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.
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