Industrial Communication Systems

47-6 Industrial Communication Systems

By performing this procedure, the microcontroller is able to check the switching capability of the input

optocoupler

and the functional connectivity of all components.

According

to

the

two-channel

architecture,

the

output

stage

is

split

into

two

switching

elements

as

shown

in

Figure

47.4.

Only

if

both

stages

switch

on,

the

output

is

activated.

It

is

preferable

that

both

switching

elements

use

dierent

technologies

in

order

to

avoid

common

cause

failures.

Hence,

the

deci-

sion

to

switch

on

must

be

done

from

both

channels

together.

Only

then

the

output

is

switched

on.

For

testing

purpose

the

state

of

the

t