ZyXEL Communications PLA-470 V2 - V3.0.5 Guía de instalación descargar pdf (Pagina 147)

Conventionally, this is a star topology. The MV/LV transformer used as the

injection point of the PLC signal is located in the middle of the star and the

PLC devices of the end users are placed at the ends of the various bus-bar elec-

trical connections from the transformer.

•

Ascom. Develops products for public and domestic LV electrical networks

using this mode since 1998. This generation of products provided a 250 Kbit/s

speed. One of the devices was used as the master, whereas the other ones were

slaves. The configuration was carried out in Telnet mode or using configura-

tion files and a TFTP client-server system.

•

DS2 and Spidcom. After having used the peer-to-peer mode to deploy it more

easily, these two manufacturers are now developing products in the mas-

ter-slave mode to benefit from a centralized administration and better QoS

management for allocating TDMA frames for real-time applications like

video.

Case of Ascom APA Devices

Ascom APA devices with a 4.5 Mbit/s speed represent one of the very first generations of

high speed PLC equipment. The master device was accessible by means of a Telnet inter-

face for the device configuration and then could be supervised from a v2/v3 SNMP admin-

istration console. The master could manage 63 slaves maximum.

Figures 7.3 to 7.6 illustrate the Ascom APM 45 master and slave devices.

Some PLC devices are used for remote telephone interfaces over the PLC net-

work. The Phonex company, for example, develops devices with RJ-11 interfaces to

carry voice analog communications over the electrical network.

Peer-to-Peer Mode

In the master-slave mode, a master device is at a higher hierarchical level (it

manages and controls the network) and the slave devices are at a lower hierarchical

level (their function is limited to communications with the master device). In

peer-to-peer mode, all the devices have the same hierarchical level and exchange

data with all the other PLC devices of the network. Therefore, the network consists

of N to N links.

128 Equipment

Table 7.2 Advantages and Disadvantages of the Number of Bus-Bar Electrical Connections

NUMBER OF BUS-BAR

CONNECTIONS

ADVANTAGES DISADVANTAGES

Single bus-bar connection

– Easier design

– Potential repetition with master

– devices

– Easier supervision

– Divided bandwidth

– Possible multipaths for circulating

– frames

– Loop possibility

Several bus-bar connections

– Broader network coverage

– Separation of useful networks

– More complicated supervision

1 2 ... 142 143 144 145 146 147 148 149 150 151 152 ... 348 349

Comentarios a estos manuales

Sin comentarios

ZyXEL Communications PLA-470 V2 - V3.0.5 Guía de instalación Pagina 147

Comentarios a estos manuales