Denso BHT-7500S, BHT-7500W user manual BCC for Horizontal Parity Checking

[ 3 ] BCC for Horizontal Parity Checking

To check whether data has been transmitted accurately, the BHT supports horizontal parity checking for every transmission block.

In horizontal parity checking, a horizontal parity byte so called BCC (Block Check Character) is suffixed to an ETX of every transmission block.

In the BHT-protocol, every parity bit of BCC is set so that all set bits at the same bit level (including a parity bit) in the characters contained in the transmission block have an even number by binary addition, excluding SOH, STX, and functions SOH$ and STX$.

(For details about SOH$ and STX$ which are protocol functions unique to BHT-BASIC, refer to the "BHT-BASIC Programmer's Manual.")

(Vertical parity)

b7

b0

Character		Horizontal parity byte
	[ For 8-bit data ]	(BCC)

Shown below is a data text block indicating the bits to be added for horizontal parity checking.

S￿	Serial			E￿	B￿
T￿			Data text	T￿	C￿
	number
X				X	C
		To be added for
		horizontal parity
		checking

184