User`s manual

Watlow Controls Communications Guide 8
Start and Stop Bits
A start bit informs the receiving device
that a character is coming, and a stop bit
tells it that a character is complete. The
start bit is always a 0. The stop bit is
always a 1.
The human speech equivalent of these bits
could be a clearing of the throat to get
someone’s attention (start bit); and a
pause at the end of a phrase (stop bit).
Both help the listener understand the
message.
Baud Rate
The baud rate refers to the data
transmission. When a change in signal
represents one data bit, baud rate is equal
to bits per second (bps). Standard baud
rates for computers are 300, 600, 1200,
2400, 4800, 9600 and 19200 baud.
Computer Languages
Computer languages are simply sets of
symbols and rules for their use. There are
many computer languages and a wide
variety of applications for them.
Programmers use languages to enable
computers to do real work.
Syntax
Syntax for a natural language dictates how
we put words together to make phrases and
sentences. In data communications,
syntax also dictates how we order the parts
of a message.