Denso BHT-6000 User Manual page 100

Transmission Code and Bit Order
All characters should be coded to 7- or 8-bit code for data transmission. The
standard data exchange code of the BHT-6000 is JIS 7- or 8-bit code. The transmis-
sion bit order is LSB (Least significant bit) first.
What follows is an example for transmitting character A (41h, 01000001b) coded to
JIS 8-level code with an even parity and a single bit each for start and stop bits.
LSB
1
Start bit
Response Method
When two devices initiate communications, they exchange signals for correct data
transmission. This procedure is called "handshaking." The sender sends a control
code ENQ (05h) to the receiver meaning "Are you ready to receive data?," and the
receiver replies to it with a control code ACK (06h) or NAK (15h) meaning "Positive"
or "Negative" for starting data transmission, respectively. This sequence is also
called "data link establishment phase."
Vertical Parity
A vertical parity bit is a redundancy bit which is added to every character to be
transmitted in order to check that data has been transmitted accurately. The parity
bit should be set to "1" or "0" depending upon the parity parameter setting, to make
the number of set bits in the character even or odd. The receiver counts the
number of set bits in the transmitted character code to make sure that it has the
selected number (even or odd) of set bits.
The vertical parity bit is positioned immediately following the MSB (Most signifi-
cant bit) as shown below.
LSB
b0 b1
(For 7-bit data)
LSB
b0 b1
(For 8-bit data)
Chapter 3. Communications Operations of BHT-6000
0 0 0 0
MSB
b2 b3 b4 b5
b2 b3 b4 b5
85
MSB
0 1 0 0
Parity bit
b6
Vertical parity bit
MSB
b6 b7
Vertical parity bit
Stop bit