ZyXEL Communications PLA-470 V2 - V3.0.5 Installationsanleitung PDF herunterladen (Seite 141)

The industrial applications that currently use PLC networks are the following:

•

sensor networks;

•

connection of programmable controllers;

•

PC located in confined spaces where wiring is difficult (on top of a crane, in

spaces with metal piping making it impossible to use Wi-Fi, and so forth).

PLC in Public Spaces

Like in the industrial world, more and more public spaces now have communicating

devices or devices fitted with Ethernet interfaces ready to be connected to a local

area network.

Many applications already use PLCs to connect these devices, particularly the

following:

•

content distribution toward interactive terminals;

•

information feedback from beverage dispensers;

•

authentication traffic for time clocks.

PLC over Coaxial Cable

As we’ll see in Chapter 7, dedicated to devices, the PLC can use not only 110-220V

50-60 Hz electrical wiring but also other wiring types to convey the signal in the 1 to

30 MHz band. One of the wirings that is the most used by PLC devices is the coaxial

cable conventionally used by cable operators to broadcast the TV signal originating

from cable television channels.

This cable has very interesting propagation and interference immunity (since the

cable is protected and even shielded) characteristics used for transporting the PLC

signal. Therefore, the coaxial cable can advantageously complete an electrical net-

work when building a PLC network in order to compensate for certain types of

topology problems related to the use of the electrical network only (network too old,

electrical network too complex with respect to the application requirements, and so

forth).

PLC Without Electrical Current

The propagation of the PLC signal over the electrical wiring does not require the 110 to

220V/50 to 60 Hz power signal. A PLC network can be imagined without electrical opera-

tion in the building as long as the PLC devices can be powered in one way or another from

a battery. From then on, they can use the electrical network to communicate between

themselves but without drawing off their power from it. This original PLC application can

prove useful in the case where the mains are cut off and in the case where certain types of

battery operated computing equipment still want to communicate during the cut-off time.

PLC in Motor Vehicles

Automobiles increasingly need to transport internal data between the various con-

trols and the instrument panel. These information exchanges require wiring of up to

3 km in length and 50 kg in weight.

122 Applications

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