Industrial Communication Systems

2-6 Industrial Communication Systems

Principally at the receiver, the series of bits has to be recovered by means of a clock signal. is timing

signal

is

needed

to

identify

the

boundaries

between

the

bits;

respectively,

the

centre

of

the

bit

has

to

be

detected

indicating

the

bit

value

with

maximum

signal

power.

Two

methods

are

used

providing

timing:

•

Asynchronous

communications

with

independent

transmit

and

receive

clock:

A

simple

method

where

transmit

and

receive

clock

are

independently

set

to

the

same

clock

rate.

Bit

synchroniza-

tion

within

a

single

byte

is

attained

by

a

start

bit

providing

the

timing

for

detecting

the

data

bits

(Figure