ESA VT130W, Руководство по оборудованию, Страница: 724 / 976

CHAPTER 35
Network connection
405.1200.037.2 - Rel.: 2.21 of 25/02/2008
35-16
ESA-Net:
Connecting
the terminals Since serial communications are highly subject to disturbances, the follow-
ing advice should be followed to reduce as much as possible such prob-
lems:
• It is absolutely necessary to use a fully shielded twisted serial cable, with
a pair of conductors having a minimum section of 0.22 mm² and a char-
acteristic impedance of 120 Ohms.
• It is absolutely necessary to use a fully shielded connector.
• The termination resistances must be placed exclusively at the physical
extremes of the ESA-NET network.
• Insert the polarization resistances of the appropriate value (typically 470
Ohms).
• The shield of the cable must be soldered or mechanically connected to
the metal shells of the connectors that are connected subsequently to the
VTs in the network.
The VT serial connection cables must be laid in separate raceways
from the power supply cables.
The VT serial connection cables must be laid in separate raceways
from the power cables and from all the devices that may, in gen-
eral, be sources of disturbance (servo drives, inverters, etc...).
The table below shows the three connectors that can be used (MSP - ASP -
Field network) for ESA-NET network connections alongside the various
types of wiring according to position held within the network.
The VT connected in the network with a connector incorporating
three resistances must never be switched off while the other par-
ticipants in the network are still on. Should this happen, the effect of
the polarization resistances will be negated and there is a possibility
that communication errors will occur.