Basic Format Of Transmission Messages - Denso BHT-4000 User Manual

3.3.3 Basic Format of Transmission Messages

Basically, the BHT-4000 transmits data as a unit of a file. First, it transmits a heading
text which includes the attribute information of a file (e.g. file name and the number of
data texts) to be transmitted. Following the heading text, it transmits the data text in
the file. A heading text and data text comprise a text.
In actual text transmission, the text is divided into several blocks, and a header and
terminator are added to each block. If the serial number management or error
checking by BCC (Block Check Character) are required, the serial number and BCC are
also added to each block. This procedure forms a transmission block. A set of
transmission blocks comprises a transmission message.
Shown below is an example of a transmission message formed with the BHT-protocol.
Text Heading text
S
O
H
S
Transmission
T
Message
X
S
T
X
In the above figure, SOH, STX, and ETX are text control characters as described in
Subsection 3.3.2. The serial number is added to every data text in order to identify
those texts. For BCC, refer to Subsection 3.3.6.
Data text 1
Heading text
Serial
Data text 1
number
Serial
Data text n
number
84
Data text 2
E B
T C
X C
E B
T C
X C
E B
T C
X C
Data text n
Transmission block
Transmission block
Transmission block