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16.1.3 Transmission speed
The transmission speed is measured in number of bits
transferred per second (bps). At asynchronous communication,
10 or 11 bits per character. 7 or 8 represent the symbol itself,
and in addition a startbit and one or two stop bits are
transmitted. The real transmission speed at 2400 bps is then
app. 240 characters per second.
Data can be transmitted in either asynchronous or synchronous
format. The difference is explained below.
16.1.4
Asynchronous format
When asynchronous format is used, each character carries a
start bit and at least one stop bit for synchronising purpose.
Each character is then independent of the others.
FS
FS
16.1.5
Synchronous format
When synchronous format is used, are all bits sent after each
other, with no extra start/stop bits. Each bit is accompanied by a
clock signa! to synchronise the receiver. In order to obtain
character alignment, it is necessary to transmit synchronising
characters prior to the information part.
Since start/stop bits are not needed for each character,
synchronous transmission gives a higher throughput.
LZTR104006 R1.00
16-3
Zat 14.4/14.4-7 and 19,2/19.2-7
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